View Full Version : Q. ECU and electrical. Not my cup of tea.

03-04-2006, 12:15 AM
Hi all! It's been a while. I wish I had my car up now so that I have more time to chat & cruise. All that fun stuff. It's been a rough 3 years. and now another challenge is upon me. So I need some assistance.
I just got my car back up and running and I took it for a drive. The alternator wires decided to burn up and cause this nasty mess. I realized this while driving the dash lights lit up. Now I fixed the wire mess and the lights are still on.
I'm not sure what caused this. The heat near the heat wrapped DP or that the current was strong enough to skip threw the wire jacket and cause the initial burn. But as a result the + and - terminals to the alt. touched and might have caused some serious electrical problems. The lights that remain on are the RAD, Batt, brake & ABS. Oddly not the engine light.
I visually looked at the Fusible links and they look fine. The car drives fine. (at least when it happened I decided to drive the extra few blocks home before I parked to turn it off) The car still idles fine. Except a little missing now and then.
I wonder if the ECU got fried. So I have this other one I purchased from someone. This one has an Eprom and was socketed. But when I installed it and turned the key to acc, there were a couple relays freaking out. So I chose to retry and same thing happened. So I didn't have the guts to start the engine thinking something's really wrong. Maybe the ECU isn't the right one. Maybe there is a circuit or wire that got messed up, up stream. Maybe the epromed ECU is bad. I don't know. And I want this car back up in the worst way. I had started insurance on it. Everything else seems to check out ok. I could put the old ecu back in and drive it. But I would rathar not until this is solved.
So is anyone willing to lend a hand or advice, please? thx!


03-04-2006, 04:59 AM
More than likely some wires are fused together (or to ground) under the dash.

The best solution would be to replace the main wiring harness.

I know, it's a pita, but fried harnesses are nothing but long term trouble.


03-04-2006, 06:51 PM
Hey, let's check a few things quick like. Since the car ran on the original ecu lets tuck him back in (btw sounds like other ecu no worky...). Now lets look at the wires again. Theres a wireto the dash,(small) and a wire to the power side of the alternator fuse in the underhood box. the little wire does the battery lite on the dash, the big wire charges the car, and there should be a ground to the case with a ring terminal. If you got these guys going the right places and the alternator fuse checks good.(black 90(?) amp fuse in front fuse block) we are ready to check some stuff . Turn the key to the on position, and check your dash lites, you will see oil,batt,brake,coolant,and abs lites stay on. check engine icon for a bit then off. Start engine, and oil lite goes out because there's oil pressure (unless it's my pos...) If the other lites stay on, it's telling us that there's no charging going on and the problem is with the alternator as the battery lite shares it circuit with the other icons.Usually this happens with a girl in the car in the rain in ohio or somehow at the most inoprotune time. If you have a voltmeter and know how to use it, it's easy, without you can only guess and that's expensive. I can only guess without the car in front of me, but it sounds like alternator toasty and battery voltage drops giving misfire. stupid question, you're not leaking power steerin fluid down on the alternator are you? been there done that, good luck

03-04-2006, 07:00 PM
The relays clicking indicates a bad socket job.

Pretty common issue on the DSMLink forums when inexperienced people try at socket the ecu

03-05-2006, 06:40 PM
Thanks so far... The ALt was purchased at Checkers Auto only 3 years ago. But only a max of 1500 miles of use. It was a XXX13 Model number. 19913 I think. Anyway there is a lifetime warr for it. So after the one wire from the plug touched the positive heavy gauge wire and caused this problem, I decided to goto Checkers about replacing. The guy there discovered a different Model numbered Alt. It was a XXX12. The xxx12 model was listed for a 91 and 92 2.0 L, manual GSX. ( I figured the guy wouldn't be hung up on part #'s if I had him check that instead of a Talon such as mine)
I was wondering what the diff was. They don't know. But since the original replacement was the wrong part #, (as currently stated in their comp sys.) that I'd try the xxx12 model #. They look identical in every way by appearance.
I do not believe that the mod #'s was a big deal or what caused the mishap because this was an all-of-a-sudden thing. And it was likely me that caused this problem having the (orig. jacket protected) wire loom rest on the pos. terminal of the Alt. The current must have been strong enough to skip threw the thick jacket and loom. Or the split loom started melting and then the jacket around the wire afterwards... The first 1500miles on this alt was ok. But ultimately it was the alt's voltage reg that failed.
Now that I have a new xxx12 # Alternator, and the original ECU back in the car, I still have the problems. The Batt checks out ok for voltages and the car idles like normal. So I'm led to believe the worst. Just like all my other problems in the last 3 years. ... It could be the main wire harness and/or the terminals under the dash that took the beating.
I'm trying to contact the person that sold me the E-Promed, socketed ECU about what to do there. Unfortunately I do not have a DSM Link YET. And I can only check continuity of the wires with my FLUKE multimeter for the basic things that are directly connected to the Alt.
So now I'm at a loss. I don't know if I should drive the car to check it's drivability in this condition. I'm afraid to use the new DSM link when it arrives. So looks like a full electrical overhaul and much time and money yet to get this going. After 3 days of Insurance and licensing, looks like I'll have to put it up on blocks once again, if I can not solve this.
... I fear electrical. Or I will have to see about paying someone locally to diagnose I guess if I can not resolve soon.

03-05-2006, 08:44 PM
hey, Im just a maroon, but i don't understand what you mean when you say battery checks ok. do you mean engine off is approx 12.6 voltish, and running is approx 14 voltish? If so, thats some weirdness to have the dash lit up. Generally, when the alt. fails to produce more than battery resting voltage, there is potential at the lite, and you usually have battery lite on, as well as anything else that's on the key on lite check circuit. If you don't have some success with this soon, pm me and i'll see if i can take a look at it. Also, imho lifetime gaurantees are only as good as the parts they come with, and many times i'd rather have a used factory part then a brand "new" (never ever worked) pile from our friends overseas in the cheap seats. If you don't have a diagram, i can gadge one from aldata for you, but let's just fix the problem and not create any more, otherwise, electrical problems can multiply and make you trully not amused. Good luck!

03-05-2006, 09:48 PM
hey, Im just a maroon, but i don't understand what you mean when you say battery checks ok. do you mean engine off is approx 12.6 voltish, and running is approx 14 voltish? If so, thats some weirdness to have the dash lit up...
Yup and yup.

03-05-2006, 10:00 PM
I hate the weird shit, however it seems to be my reason for living...Anyway pm me for my cell number and let's take a look, it will save a lot of space. I'm really not that far away, and now i'm curious. I've killed a few alternators in my day (i like lights at night!) so i'm familiar with some of the more typical issues, and i can provide harness or whatever to bannish the gremlins back to the triumph you must have parked next to.

03-09-2006, 12:11 PM
Thank you 'Prnounced Odd' for your help so far!
I will let you know the developments here when I
discover more to resolve. My hours are hectic now
to mess with it much. But now it runs!!!
I have to admit I'm happy to announce my
stupidity as opposed to extra electrical grief.
I'm official now. I'm an "ID-10-T"
The alt fuse WAS blown and it didn't look like it was
originally until closer examination.
Those buggers are not cheap!! $16.xx retial. $8.xx
at MMM with discount.
Afterwards I had to drive about 50 miles to enjoy the
car. It drives fine. With my TMO DataLogger everything
reads nicely. However, I have a 1st gear and reverse
not working that well.
I smoked the tires badly entering traffic and I
believe the ACT2600 was slipping nicely as well.
I might have to replace it with a 2900 now. :( We'll
Thanks guys for your inputs. All this work I've done
couldn't be done without your help.
Have you ever had a brain fart like this one? It's
as bad as if you try to blame the computer for not
working before you realize you forgot to plug it in.
hehe. ... Allen, you know what I'm talking about.

Now the E-promed ECU still clicks after retrying. So
it might need to be resocketed.

... I must also include that some of the wires had
to be replaced and the alternator was as well.
... I still can not find info as to what the
difference is between the two alternators that
Checkers had available. The only one that matched in
thier computer was the 15512 part number. However I
was driving with thier 15513 PN, for a few years.
ew - no more blinky dash lights except the ABS still

03-09-2006, 06:57 PM
Been there done that, kinda. Happy to hear you're motoring again, it's always nice grabbing a few gears after getting your ass kicked by car. Why, for two minutes you hardly even notice rattles, noises, vibrations, or other facts of life. I may be wrong, but the different part # question is probably one of output amperage. The same alternator case is used on many cars, and (unlike audi with their upgraded internals and nice ducting) the factory engineers didn't seem to mind putting it right next to the turbo, and underneath the( leak looking for the worst time to happen) power steering pump. I've noticed that the base cars have 65 amp and the real cars have 75 amp, and I've always wondered if the cool guy cars like the 3000 vr4 have higher ratings, anyone know? Factory specs are about electrical content, accessories a/c etc, and, generally automatic trans rated higher. Anyway, on to the next issue, and the next

03-10-2006, 10:54 AM
While it's good to have adequate amperage for your electronics. My question would be what is the necessary minium? I will be running less than stock needs other than a aftermarket radiator fan and a laptop. No A/C but just the dash fan for ventilation.
I do believe that the 15512 is of a lower amperage but I cannot find out how much. The 15513 was a dollar and change more. I had the 15513 but then asked to change it and then they gave me back some money. So I have my doubts that the 15512 is of a higher amperage. I would guess the 65 and the 15513 is the 75amp style.
If some cars came with the 65amperage, I can only guess that it should be the minimum. I don't know if there is any drag differences on the engine because of this. In theory, the lower amperage alternator may be a better way to go if the larger one is not needed. But not sure if that is a noticeable concern.

03-10-2006, 11:13 AM
The alternator is a dynamic charger. It will only put out enough to cover the demand. No more, No less.

If you start drawing too much current that the alternator can't keep up with, then you start getting the dimmed lights and lowered voltage throughout the system.

Get the higher amperage one if you haven't already and call it a day.


03-10-2006, 11:17 AM
Uhm, I was informed lately by the people who do the custom high amp alternators that this is not true in our cars. For instance, if you were to unplug your battery and run just off the alternator you will burn it up. It's a device that is supposed to keep a steady state. For instance it will try to keep a constant voltage which is fine, but the amperage changes depending on the battery charge. So that it has time to cool down. The higher amperage ones just charge the battery back faster so they don't generate as much heat.

03-10-2006, 10:18 PM
:confused: I think there's some good questions here. I know a little, I'm sure somebody else knows more. Some things to remember, (if'n i recollect corectly) alternators work by passing some small amount of current onto the rotor sliprings via the the brushes. As the rotor spins it creates an alternating magnetic field, which thru the magic of physics induces the goodness necessary to keep things humming into the stationary windings of the stator. So, to make more goodness, more power across the brushes, stronger field generation, more happiness occurs at the stator. At this point, it's actually a/c and is converted into somewhat stable dc voltage in the rectifier, by zenier diodes.The voltage regulator controls voltage by varying the current to the brushes and there you go, juice.. All this makes heat and costs power, so the factory usually sizes fairly wisely, unless you like music you can share with your neighbors, or you want other current hungry goodies, (I like lights!), at which point it's like my bank account, not enough in, lots out, at times. The battery can take up the slack somewhat, temporarily, but low battery voltages play havoc with fuel pump pressure and other tuning parameters. So, how much is enough? My guess would be, turn on everything you got, and check voltage at the battery with a voltmeter, at idle and 2500ish rpm. If you don't drop under 13.5 voltish worst case @ 2500 you're probably good to go. At idle you'll probably see you're not keeping up with demand, and you're making a lot of heat. I did a little research, base manual trans cars 65 amp, usa automatics, and turbo cars 75 amp, and then it gets interesting, further research shows canadians get 75 amp base, and those wily cannucks get 90 amp on automatic and turbo cars. So, 90 amp oe alternators exist, at least according to my service information. Any cool guys at the dealer to check part numbers and apps? I know there's some guys posting here that know way more than me about this, let's hear your ideas. One interesting anomoly about these alternators is the amount of temperature compensation built in. Cold, they make sexy power, lites brite, stereo loud, but, hot, heat soaked, they don't have much reserve, and it's easy to get behind the power curve, cruising with the headlights on, stereo bumpin, a/c chillin, etc... all it takes is a little time at idle and you could have issues. So, fellow motorists, let's adjurn to the drive with a voltmeter and play a little and post results. I can't help but think someone's figured out the cool guy upgrade, please share the goodness with those of us who like too much of everything! thanks, sorry long post!

Bryan Savage
03-10-2006, 10:31 PM
As I recall, Galants all had 90 Amp alternators.

Varying magnetic fields induce electric fields. Varying electric fields induce magnetic fields. The rotor inside the alternator has magnets all around it. The stator (I think that's the name) has magnets on it too. As the rotor is turned by the engine, the magnets pass each other and induce an electric current which goes to the fuse box and the battery.

You get alternating current because the magnets change polarities as the rotor spins. This is how electricity is generated at power plants, except for most of them burn coal to produce steam which spins the rotors in giant alternators. The current changes polarities sixty times per second here in the United States, which is why your appliances are rated at 60Hz. The voltage in your wall socket changes from +110V to -110V sixty times per second. Water turbines are just big alternators too.

Cars don't run so well on Alternating Current, so they have "rectifiers" to smooth the power pulses into a constant positive voltage (Direct Current).

03-11-2006, 09:02 AM
You are correct, MD149750 is for the e39a Gvr4s and crosses with the base galants. It is listed as a 90a alternator.

Weird though, I thought that my "lifetime" replacement, Chinese guts, alternator from Advanced was 75a?

All the 3KGT are listed as 110a and one is 95a. The NT models are mostly 110a except for the non-sunroof and SOHC models, they are 90a.

The 2.4l late-model eclipse is listed as 90a.

All the Expo pieces are 75a and less. Stay away.

03-12-2006, 11:48 AM
I knew someone knew something about this. Alrighty then, my experience goes like this. Factory fitment is usually adequate for average schmoes, it's only people who play with cars that break/stretch the weak parts of a system. In the case of the charging system, we can place extreme demands on the system without even knowing it. Turbo timers for instance. Set to run for four minutes, fans probably cycling, battery voltage, at hot idle will suprise you. Hang out, maybe share some music, etc.. now it gets interesting, turn the key, and sometimes the results will disapoint. The electrical parts of these cars see way more underhood hot soak than you would think, and heat makes electricity lazy. Breaking the system down, battery capacity is the main factor for happiness. It's a function of installed battery quality (i like optimas, but thats just me), and then just keeping it topped up. (i know there's more to it than that, but posts keep getting looong) That's about the alternator, and I have seen the insides of a few, as I'm sure others have. You get what you pay for, and the insides of an alternator case are an object lesson in economics. Factory diode packs are mounted on nice heatsinks, and internal connections are via metal straps, and the regulator package stands up well to having a 1500 degree neighbor, all things considered. However none of this matters, as the drive beckons... turn the key, click.. girl looks at you, you see that comercial in your mind..it's not all good. Or, it starts, you turn on heater or a/c, headlights, etc. and then the batt,coolant,brake lite trifecta appear (dega' vu, all over again, for some of us.) Most of the time, it's because we asked too much at once, and either the worn brushes just gave all in a brief orgy, or one of the straps acted like a fuse link inside, (eric, if one end of that touches the case, that can do what happened to you, btw) or any one of a number of issues can occur. Point is, the oversea rebuilds have some extra built in issues, above and beyond because of cost considerations, (diodes and heatsinks cheesier, and other components not really happy with having heat to the east and powersteering efluvia from the north) Making current at idle, hot asks more from the system than everything on at highway speeds, so just understand, keep from loading a system down from a discharged state, (when was the last time this car ran.... :p ) and give the system a chance to put a little into the battery before you blast off (a discharged optima will try and pull 45-60 amps @14.5 for a few moments if you've been mean to it... did you plug that coil pack in.... no i thought you did.. :rolleyes:) Point is, alternators can live a long and troublefree life given the chance. When failure does occur there are choices, and one of them is to repair what you have, I'm an old guy, and in between setting points and other arcane tasks back in the day, we used to rebuild alternators and starters... and the parts still exist, from other old guys...So think about it before you get a "lifetime" whatever from the cheap seats, they know most of the people who buy cheap parts are just trying to get by and the vehicle won't generally make too many more miles. And, the boneyards can produce usuable cores for science projects/upgrades. If someone can tell me what part number/applications we're looking for, I can procure a few for interested parties, and then we're only brushes and a little tlc from charging bliss. Let me know, I like to play cars.

03-12-2006, 11:33 PM
That gave me a headache trying to read that

Please use the return key to separate your ideas. It only makes it a lot easier to read.


03-13-2006, 01:20 AM
So, I'm not even going to read most of those run on sentances. They're more of an eyesore than anything. Our cars were not designed to run off the alternator. They were designed to run off a closed loop battery system with the alternator keeping state (taking up the slack). I've talked with a few people who make some damn fine alternators for our cars (135 amp lifetime warranty) and they say the alternator should NEVER be placed in a position where it is the sole feed for the electrical system.

I've said my piece, do as you may. Matters not to I.

03-13-2006, 09:31 AM
I just read what I wrote. You're right, it's a little ugly. As you can see, I'm not an educated person. My "sentances" run on a bit, and I don't seperate thoughts well. That was`an ugly paragraphish of free thought. However, there's a lot of people who will read and never post because somebody will bust their chops. If'n you read the entire saga, you'll see I helped (albeit a little) did you? What can I say? I rode the short bus to the auto shop, and that's where I live and work. I'm ok with that. I will try harder to organize my thoughts, and I apologize for free thought, but it's how I am. Thanks, and you are right it was `ugly, no excuses...

03-13-2006, 09:45 AM
odd is right. Most people never look to see if the issues they are having are due to insuficient electricals. Example: at full tilt boogey the average "race car" is driving-
an ecu
fuel pump or pumps
dash electricals
all those spiffy aftermarket gauges

These demands typically will exceed the output of the alternator, drawing the difference from the battery. This is typically not a concern for drag racers and most street warriors. Track racers however, are typically borderline. I have log after log of battery voltage dropping down as far as 9volts towards the end of a straight, doing bad things for fuel pressure and coils/injectors. Drop low enough and some ecus will shut down.
You might think this wont ever effect me. Maybe, maybe not. If you have electric fans, headlights, A/C(also covering defroster), decent stereo, electric seat warmer, heated coffee mug, etc running while you are driving around you can easily exceed the alternators output even just loafing around. Start actually driving spiritedly and things can get interesting in a hurry.

03-13-2006, 09:51 AM
If I wrote a three hundred page novel that was one huge run on sentance most people would not want to read it. Granted there would be those that would for its content but the human mind needs structure. Yes most people don't post because they'll get their grammar and sentance structure attacked but there are rules to this board for a reason. It's not because we just felt like being dicks. I'm not saying your information was not valuable. I was saying I didn't even bother reading it because it was too tedious.

Bryan Savage
03-13-2006, 10:20 AM
Crikey! He apologised! No need to whiz on the electric fence. :)

Just get a piece of paper and put it on the screen to help you keep your lines straight. ;) (that's what I do)

^^^Notice the smiley and winky. This means I'm not flaming anyone! :D

03-13-2006, 10:31 AM
Ok, everyone (including me) back on topic.

03-13-2006, 09:02 PM
:D Constructive criticism recieved and understood.

Topic was`alternator failures and what to do next.

Has anyone done a factory upgrade?

Does the 3000 unit bolt up? Is the harness connection the same?
I don't think the harness/fuse will ever see 110amps, but the fuse rating on 1g gsx is significantly less. Does the 3000 have a bigger wire running from the
alternator to the fuse box and/or higher rating on it's fuse?

I don't have several hundred dollars to thow away on whiz bang stuff that I can't service myself. I've also noticed how hard it is to have aftermarket alternators repaired/serviced in another state. I drive a lot!

I know better than to buy overseas/cheap parts, because I'm hard on stuff.

So, dazzle me with your brilliance, your wisdom. Make my lights burn brighter. Make my stereo hit harder. Show me the way to electrical nirvana.

03-14-2006, 12:55 AM
Well, I've no idea about your audio stuff, since I don't own one vehicle that has a stereo. But... I have a direct drop in 135amp lifetime warranty alternator that's resonably priced :)

03-14-2006, 10:02 AM
How much? Who makes it? Who sells it?

And, the stock 1g fuse is 80 amp... 135 amp into 80 amps = roadside tooldrill, as the fuse bolts into box...

I have been running 75 amp without major issues. I do see higher demands than most, because I'm hard on stuff. With lights, heater and wipers, and hotel (car operating systems), I'm putting some serious demands on the system. Add radiator fans, and I'm stressing the system more than I like. It doesn't break, it just works harder than I like. Fusion brings up voltage sag. It's a bigger problem than a lot of you know. It's really hard on fuel pumps when they don't have sufficient current to produce the volume at the required pressure to make the power we all want to make. Also ecu's and other items that depend on stable voltage get worked a lot harder than they should, and fail a lot more often when they don't see adequate supply. I can't help but think a lot of people have had mysterious issues with tuning that were simply voltage fluctuations. I'm sure those with data loggers and high zoot gauge packs know exactly what I'm talking about. The temp compensation built into these alternators, along with underhood heatsoak issues mean there's very little reserve left after an uphill battle with your favorite twisty...

Again, Dazzle me with your knowledge, please. Gvr4's are fairly rare in the boneyards. Does the secretary version galant also run the 90 amp? Will the 3000 units bolt up? How about diamante? They had a lot of extra crap that requires upgraded charging system specs.

Speaking entirely for myself, I like to play cars. If I can find what I need in the yards and repair/ service it myself, I consider that success.

And, yes, I know, you never get rated power from any alternator. All I need is about 90 amp, well regulated. That should make at least 60 amps without straining too hard.

Thanks for the space.

And, sorry, I'm not very good with words and sentence structure and the like. Please don't bust my chops, and I won't type drunk, deal?

03-14-2006, 11:44 AM
LoL... For a Galant it would be a 1G alternator. They're made for me from a reputable shop. I handed out the info a while back I believe because they decided to actually start producing and selling them. http://www.4alterstart.com

Do a search for a 1G DSM and it should show. The fuse is easy, just remove the alternator fusable and add a 160A breaker like all of us do :)

03-14-2006, 10:02 PM
Nice link, nice site, nice piece. And the cost? Thanks.

Still, I'd like to build my own. I know that every piece I put on my car is up to spec, because I made it that way. My wife calls it the hard way. I call it peace of mind. Alternators aren't rocket science. They are simple electro-mechanical devices. Within the manufacturers model line-up are higher end models, factory fitted with what I need. I can pick up an alternator for 15 bucksish at the boneyard. Test it, dissassemble it, replace the brushes, reassemble it and I'm good to go 50,000 miles. The parts set inside are replacable items available from a man I've known personally for 20 years.

I like to play cars. It's that simple. If there's a way to make it better, stronger, or faster, I want to do it myself. It's a learning disability, I'm sure. But I can't help myself. Surely other people play cars, too? Money saved by building your own pieces buys a lot of other goodies. Things like intercooler piping, stainless steel lines, fuel system components and other supplies to ensure we'll have plenty to adjust, fiddle and fondle.

Anyway, I think I've beat the topic to death, and then some.

Anybody else have imput?

03-15-2006, 01:11 AM
Nice link, nice site, nice piece. And the cost? Thanks.

Still, I'd like to build my own. ...If there's a way to make it better, stronger, or faster, I want to do it myself. ... Money saved by building your own pieces buys a lot of other goodies.

A thanks goes out to John "pronounced odd"! For stopping by today and brainstorming a possible solution with my car's shifting issues. Also, he solved my ABS lightting up on the dash and going out. That happend to be the motion sensor under the back seatbelt that was unplugged. :p
Anyway. I'm going to try to bleed the clutch line a certian way to see if that solves anything and I'll let you guys know how it turns out.
Thanks again.

03-15-2006, 06:43 AM
Money saved by building your own pieces buys a lot of other goodies.

I'll agree with this!


03-15-2006, 10:10 AM
I came here for information. I want to know more about these cars. I know some of you know a lot about the subject. I want you to share the wealth with those of us who are less knowledgable. I know my limitations. Proper english is not a strong point of mine. I'm ok with that. I say what I mean, and mean what I say. I can see people have been following this thread, (probably for the entertainment value...), and I know some of you know what fits/works. Please post up your solutions, and we can all learn something.

I don't build my cars with my checkbook. Somebody else doesn't build my cars for me. I build my cars with my own two hands, busted knuckles and all.

I value real people. People who work on their own equipment. People who share what they know. People who speak their own minds. People who can seriously foul up the works, and still laugh at the end of the day. To you I say, break a bolt, call me we'll get it out. Smoke a harness, call me, we'll solder in a new harness section. Just understand, honest mistakes make funny stories. Anything else is just b.s., and self serving at that.

My last post on the subject.

And, eric, nice car! Makes my pile pale in comparison. A few small details and you'll be good to go.