I'll keep this short and sweet, 1989 Formula Firebird 305 TPI (original)

Here's a list of things i've experienced with my car:

1) My ECM will go bad every year or so.... I'll get an SES light, change the ECM and the SES light will go away.

2) I have code 42 now, the car seems to only have the code when it's cold. After the car warms up, if i shut it down and start it back up, the code usually goes away.

3) Recently, my radiator fans stopped working (probably a seperate problem). I had been swapping the relays for the radiator fans and the HVAC fan recently, could my problem be that I burnt out my relays from switching them?

4) I recently probed all of the ports on the ECM with the car off, and the key on, and all of the voltages seemed to match the values below:

Key on Engine off:
A1 - 12v, A2 - 12v, A3 - 12v, A4 - 12v, A5 - less than 1v, A6 - 12v, A7 - 12v, A8 - 2-5v varies, A9 - 5v, A10 - Speed Signal, A11 - 0v, A12 - 0v,

B1 - 12v, B2 - 0v, B3 - 0v, B4 - not used, B5 - 0v, B6 - 2.5(vats), B7 - 9.2, B8 - 0v (A/C off) or 12v (A/C on), B9 - not used, B10 - 0v or 12v (park/neutral switch), B11 - not used, B12 - 2.5

C1 - 12v, C2 - 12v, C3 to C6 - not usable (IAC), C7 - not used, C8 - 0v, C9 - not used, C10 - 1.7v (varies with temp), C11 - not used, C12 - 2.0v, C13 - .54 (TPS signal), C14 - 5v, C15 - 12v, C16 - 12v

D1 - 0v, D2 - 0v, D3 - 0v, D4 - 0v, D5 - 0v, D6 - 0v, D7 - .35v to .55v (O2 sensor), D8 and D9 - not used, D10 - 0v, D11 - 12v, D12 - 12v, D13 and D14 - not used, D15 - 12v, D16 - 12v

5) When I have code 42, the car runs badly.... there is still spark advance according to my laptop, but the car goes nowhere when i floor it.

6) When I have no SES light, the car runs perfectly fine.

 

this ended up being a bad ECM..... for those that care

 

next time the ECM goes bad, you said they blow yrly, open it up and see what part of the board is frying if so, that can help allot.

I was ready to goto a carb till I figured it out at the last sec