Bad ECM

[Ajillag]

My chevy is not relaying the odbI codes. I tried the paper clip thing and then went and bought the code reader from autozone but it's not working. Could these mean my ecm is bad?

[Blue Bowtie]

It might. One thing to check is whether the "Service Engine Soon" (SES) light is on when the ignition is on, engine off. If so, the ECM is at least operating SOME its ouputs, and has SOME inputs.

Another thing you can do is watch the SES when you first turn on the ignition (without starting the engine). The lamp should turn on for about a half-second, turn off for about a half-second, then turn back on and remain on until the engine is started or the ignition is turned off. This "SES bounce" is the confirmation that the ECM has passed some rudimentary power-up self diagnostics. If the MEMCAL or PROM is not inserted properly, connections at the ECM are poor, grounding is incorrect, or the ECM is damaged the SES light may not operate as designed.

Before condemning the ECM, disconnect the electrical connectors at the ECM, inspect them for corrosion and damage, and reconnect them. Sometimes the cleaning and reseating of the connectors can re-establish a poor connection.

[silicon212]

Also, check your fuses. There will be three - ECM, IGN-ECM and GAGES.

The GAGES fuse is 20 amps, the other two are 10 amps.