Crazy electrical problem, module count / wiring diagram?

Hey guys, I need some help Re a sourcing an electrical fault in my car thats sending many other components into a frenzy.

I think it maybe a grounding fault of some sort but locating it is becoming a night mare.

I want to ask if anyone has a complete list of any/all modules in the gto gen 1 (1992 if it helps) jap import and or a full body harness wiring diagram?

The car does crazy things when certain buttons are pressed, example, when fog light is pressed the ECS module seems to lose power and resets itself.

When the high ram switch is held the speedometer sits at 20mph

When the side lights are switched on the interior lights sometimes aim and the air cod panel goes off.

If the cruise control button is pressed the abs flickers, the overheated cat light shows and the dash buzzes.

When the ECS button is pressed sometimes the check engine comes on and sometimes the ACS light shows or the abs flickers.

All the buttons so far (at least thst I’m aware of, including all those mentioned in my examples ) have been fully reconditioned/refurbished and confirmed working with multimeter as they should.

That sounds like a tricky one to diagnose. Don’t suppose the electrical manuals here are what you’re looking for: Manuals - Stealth + 3000GT / GTO

Have there been done many mods to the stereo, speakers, amplifiers and such in your car??? Those things can cause havoc if not done properly…

If not, then you just gotta go the long route and checking every fuse, module and so on…

There’s no sound system in the car, but Re checking modules thst was my question :slight_smile:
I’m asking for a complete list of modules / layout so I don’t miss any

Maybe a long shot but try to disconnect the ECS module. When faulty it has been known to cause some electrical issues…

I think it would be easier t find the holy grail than to find the miracle diagram that will give you a simple answer to this problem without you having a good knowledge of electronics.
Here are some things that you need to think about.

  1. Is there anything at all that led to the problem ? eg, adding or modifying any electrical part of the car, any repairs carried out to any part of the car, do you have an alarm, have you gone through deep water or hit a speed hump?
  2. There is a video being uploaded for next week which shows the location of all of the control boxes but I can tell you now that this will not help to solve the problem because the symptoms you describe relate to multiple system problems and it is not likely that they would all fail at the same time unless you had a major power fault.
  3. Is your battery fully charged and holding a good charge as a low battery can give weird faults.
  4. Have you checked the connections to the battery are clean and tight?
  5. Check as many earth points as possible for corrosion or breaks.
  6. Finally, I have found that about 80% of electrical faults are down to recent or previous modifications which have not been carried out correctly.

Thanks Joe.

I’m generally speaking fairly knowledgeable on car electrical systems so fortunate enough to have the ability.

I’ve slowly been taking the car back to standard after some botched wiring from a previous owner.

I’ve been tracing bad wires slowly but surely.

I’ve tried unugging various modules such as ETACS, ecu, power fold mirror module and ecs module but problems still persist

I’ll try to answer numbered questions to help a possible responce.

1, the car was bought as a barn find, so I know little history on the car, the faults are all presant when I purchased the car

2, thank you, the video may help as I’ve already had to repair several modules with corison and even one that was shorting out due to cap leakage, so your video would really be helpful so thank you

3, battery is charged and is connected to an industrial grade battery charger capable of several hundred amps and smart monitoring.

4, yes this was the first thing I did :slight_smile:

5, the earth’s are somthing I feel maybe part of the problem and was part of hoping to answer my question regarding where all earth strapsay be (including in a possible wiring diagram)

6, I believe you’re right, but since I’m undoing a previous owners bodge ti don’t know what’s been done and is now on me to restore it

Once again thank you for all help!

Just an additional note, the thing I’ve found with this cars is thst most systems are independent of each other unlike modern cars, ie my power fold will operate independently, as will the ECS, the pop up lights etc.

But the part thsts strange is thst these cars lack a canbus system yet several systems seem to be causing faults with other systems.

Like the pop up lights seems to make the ABS light come on and pressing the fog lights seems to put a warning up for the temperature sensor in the exhaust

sounds more like a bad earth problem to me. I recall a bad earth on an old car on the rear lights. The earth was bad so the volts found another route ie through something else which shared the same earth point

Thanks for that! I do also think it’s either a bad ground or possibly a short, those photos help thanks!

There’s tons of circuit diagram pics in my book but it’s hundreds of pages.

May I ask where you purchased this book please?

It’s the 1992 electrical tech book. The original owner had it with the car.

thank you! very much for that

More manuals here

more manuals credit to Titch2000

Thank you!!
I had a good look through it seems that the LHD grounding locations are not all the same as RHD (and not mirrored either)