80Sierra

Just finishing up an install of an 04 LM7 5.3L into an offroad buggy. Everything is working correctly, except the SES light is turning on and staying on for approx 20 - 30 seconds after shutting the ignition off. I have confirmed that the PCM has all it's grounds connected, and both the ignition wires and battery wires are hooked up in the proper spots and working as they should.

The SES light turns on properly when you turn the ignition on, the PCM communicates with my OBDII scanner when the ignition is on, but not when it is off. The SES light goes out when the engine starts and does turn back on if a code is set.

Does anyone have any ideas why it would turn on when you kill the engine with the ignition switch? Or should I just hook the SES light up to an ignition 12V signal instead of a battery source (done as the battery source was convenient, no ignition circuits nearby...)

Thanks!

Russ

Haggar

Typically, in the OEM cluster, the SES light is powered by ignition, not constant battery, so that may be your issue. (I design instrument cluster electronics, including the new Camaro).

It would be ignition source connected to the high side of the SES light, and then the low side is connected to the SES wire to the PCM.