ECU Ground Connections Under Manifold Location?

warmblood58 · Post by **warmblood58** » 29 Feb 2016, 11:11

Thank you, (I have full dash and instrumentation except the whole lower bank of warning lights (2 rows) located along the bottom of the instrument panel (both right and left) These are the lights that come on in position 2 right before starting ( I think about 17 or so, like SRS, ABS, oil, battery, etc. Thanks! This car sat for six months with a dead battery (previous owner did this) but did run up until that time. At first, I did not have dash lights but I bridged the dimmer pins and voila, had dash again but still no warning/indicator lights. Perhaps a reset or other though I have been reading about volatile memory, very important to keep these ECU's energized. Thanks again for your help! Also, this car has IPD's flashed ECU upgrade -

Post by **erikv11** » 29 Feb 2016, 12:37

You might want to grab another ECU while you are messing around with possible wiring issues. For sure any turbo ECU from 95-96 will do just fine, although the emissions may not match and you could get a CEL for that. If you could only get the CEL to show ...

Post by **abscate** » 29 Feb 2016, 12:43

warmblood58 wrote:Thank you, (I have full dash and instrumentation except the whole lower bank of warning lights (2 rows) located along the bottom of the instrument panel (both right and left) These are the lights that come on in position 2 right before starting ( I think about 17 or so, like SRS, ABS, oil, battery, etc. Thanks! This car sat for six months with a dead battery (previous owner did this) but did run up until that time. At first, I did not have dash lights but I bridged the dimmer pins and voila, had dash again but still no warning/indicator lights. Perhaps a reset or other though I have been reading about volatile memory, very important to keep these ECU's energized. Thanks again for your help! Also, this car has IPD's flashed ECU upgrade -

I keep trying to ignore that upgrade since its just another variable in the mix (I know nothing about them, so I can't add value here)

The program in the ECU isnt volatile and doesn't require voltage to retain itself.

Have you found the dash wiring diagram on the web yet??

warmblood58 · Post by **warmblood58** » 29 Feb 2016, 19:56

My next move is to check wiring diagram to see why warning light circuit might differ from other instrumentation. If ECU was fried, I would think cranking would be shut out with other functions =might try to reset tomorrow

Post by **erikv11** » 29 Feb 2016, 23:35

I don't think anyone is suggesting your ECU is bad, not sure what you are saying.

If you are referring back to my post, maybe I can clarify my point: you seem to really like that IPD flash, so as long as you are screwing around with wiring why not protect it and use a throwaway ECU for now? They are a dime a dozen at the wrecking yard.

warmblood58 · Post by **warmblood58** » 01 Mar 2016, 11:02

I have a pair that came from an '97 but the markings are different - I don't see Motronic 4.3 labeling and thought about trying this but decided not. I did notice something strange the other day. While working around the battery and cleaning up connections, I hooked up negative terminal with blue wire only attached and no black neg cable (cable was hanging detached from neg terminal connection. In Position 2, the left bank of warning lights lit up but not right bank. When I noticed that I had not attached black cable back to post, I reattached and had no warning lights again . . . Does anyone one know if there is a third wire attached to ground at battery (in addition to black and blue cables at negative battery terminal? Previous owner admitted that he did not know much about electrical but I see evidence of where he has been . .

Post by **abscate** » 01 Mar 2016, 13:06

You really don't want to do that. When you have 12 VDC on part of the car, and are grounding only parts of the the circuit, you will see all kinds of weird things happening - weird until you see that 12 VDC will ground itself through other components - none of which is good.

Sorting out wiring butchery is really nasty work.

Post by **JimBee** » 01 Mar 2016, 20:58

Look for a ground behind the passenger side headlight, hard to locate. Somebody posted a thread on that a while ago, said it's a common source of no-start.
Good luck.

warmblood58 · Post by **warmblood58** » 01 Mar 2016, 22:13

Thank you!

Post by **erikv11** » 05 Mar 2016, 22:52

warmblood58 wrote:I have a pair that came from an '97 but the markings are different - I don't see Motronic 4.3 labeling and thought about trying this but decided not. ...

Just FYI, about this side thread: the 97 ECU (any P80 turbo ECU) will work just fine in your 95, regardless of whether the ECU is m4.3 or m4.4. If it's m4.4 you can enjoy the quicker startup and "other engine management advantages" (whatever those may be, exactly ... ). But an emissions code is likely as mentioned. If you use a 98 ECU the AC won't work.

ECU Ground Connections Under Manifold Location?

Re: ECU Ground Connections Under Manifold Location?