Hello Brickxperts,

My boy's 740 (1991 body with 1990 engine) has given us the check engine light. 1-2-1 was the code. We changed out the AMM with a good spare, still getting the light and the 1-2-1 code. Anything else I should look for? What possibly (other than the wiring harness - please! no!) could be throwing this code at us.

Thanks for the advice, as always.

Dennis

Hi Dennis,

After you check for snafu AMM connectors and use the CRC spray
You can also check to see that you have full battery voltage
at the AMM

Pin 1 /Brown wire = Ground
Pin 5 /Blue/Yell wire = +12.6 engine off <+14 running

Could be a ratty ground or Pos terminal connection.

Don't worry too much about a harness problem,
besides the above, there's only three direct wires to the ECU

Good Luck, Bill

Check for corroded or dislodged connector pins at the AMM.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Thanks Bruce will do. Isuppose also there exists the possibility that the second AMM is also bad, being it is from a parts car .....
Dennis

If you didn't do this with the first AMM, suggest you do it with both. CRC Mass Air Flow Sensor Cleaner. $6. Clean them thoroughly. This has worked wonders on the AMMs on two cars, in the many months since I gave the first AMM up for dead.

It's about the only stuff out of a can that I believe in.

Except for beer, of course.