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Thread: ecu works in one car but not the other [SOLVED]

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Posts: 21-25 of 25
2013-10-16 12:41:11
#21
Next step. check the voltage at pin 20 on the ecu with the key in the on/run position. You should have 12v. Do this with both ecu's.

Another step to try with both ecu's. Remove the distributor, turn the key to the on/run position and rotate the distributor. After 180 degrees the fuel pump should turn on. If this is not the case with the b14 ecu, then the problem is likely in the wiring between the distributor and the ecu.
2013-10-16 23:07:15
#22
While checking ecu pin #20 i did not get 12v with either ecu.

With the b14 ecu I got 24.3mv the entire time
With the g20 ecu I got 14.3mv while the fuel pump was priming and then after prime i got 24.3mv.


When I removed the dizzy and tested like you said above

The g20 ecu turned on the fuel pump after 180* rotation
The b14 ecu did not turn on the fuel pump after the 180* roatation

I checked for any visible damage, burns or signs of problems with the dizzy wiring and did not see anything. Im going to trace all of the wires tommorow morning when i have some daylight to work with.
I did notice this little gray box, its a little more then 1 inch long and about 1/4 inch wide. What is it for? Could this "blow" and need replacing? Here is a picture of it. A little more research and I found out this is the resistor. I will be deleing this as I have a vvl dizzy, and it has a resistor built into it




While messing around with unused plugs in the engine bay, I noticed that this plug would kick the fuel pump on when it had 12v source. However it would make constant power to the pump and it would not kick off after priming.



As you can see it is a black wire with yellow stripe and a black wire. when I close this circuit it blows the fuel pump fuse. I dont think this plug will effect anything though, I was able to check out my buddies vvl swapped car and this plug is also loose in his bay.

On my 96 b14 that has a 98 motor in it this plug goes to a black box type thing between the uper and lower intake plenums. This might not be relivent but I thought I would throw it out there.
I also have a few more unused plugs in the bay, but I think its all useless emisions stuff. I could snap some pics if you think that would help.

I think I am just going to throw a new engine harness in the car, this is starting to get way too time consuming.
Last edited by D-Unit121 on 2013-10-17 at 05-33-39.
2013-10-17 14:04:10
#23
I think a new harness is the best solution. Both ecus are nearly the same as for the pinout, but the b14 ecu uses a few more pins than the p10. I have a feeling there is a short in the harness that is keeping the b14 ecu from working properly. If I can make a suggestion, wiring specialties, a vendor on here, has been itching to get his hands on a b14 harness so he can start making and selling harnesses. Get in contact with him and see if you guys can work out a deal to get your harness repaired.
2013-10-17 17:34:53
#24
I found the issue with the harnesss today. The car is running with both ECU's now. It was a loose prong on one of the interior harnesses that go into the engine harness.

@ebinkerd thank you for your help with this issue
2013-10-18 03:05:47
#25
- - - Updated - - -

Originally Posted by D-Unit121
I found the issue with the harnesss today. The car is running with both ECU's now. It was a loose prong on one of the interior harnesses that go into the engine harness.

@ebinkerd thank you for your help with this issue


YAY!!! Can you post which pin was causing the issue, and what circuit it was in. This is for searchability.
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