Battery drain problem

[capbuster]

I'm wondering if anyone has any ideas. I have a 2 amp draw that I cannot find a reason for. Yes, I said 2 amps. My car is a '67 Camaro with an LS1 motor, American Autowire harness. Optima Yellow top in the trunk. I'm finishing up the wiring now, but the battery will drain overnight if I leave it connected. Engine bay is essentially complete, the engine runs, (runs pretty well!!) I have resolved most of the circuits and have any potential shorts eliminated. I have tested with the amp meter with a friend watching the meter as I pull the fuses, no change. Disconnected the alternator, no change. All I have left is to examine the connections at the starter.

This is driving me crazy....... I have checked/disconnected the power to the relays for the fans, for the headlights. Disconnected power to the ignition switch.

Could a problem with the PCM cause some type of circuit to remain powered and draw current? PCM seens OK because the engine starts/runs/idles, etc. Hooked up to a scanner it does not throw any codes.

Any help would be MUCH appreciated.

[CarlC]

Can you disconnect the engine and lighting harness from the firewall plug? If so, disconnect one at a time to see if there is any change. If not, and if your cabin power is routed through the plug, then the problem is somewhere forward of the firewall. Then start disconnecting everything until the problem goes away. If it does not, then there is something awry in one of the harnesses.

[ProTouring442]

First I would pull the alternator wires. If that doesn't fix it, pull all the fuses. If, with all the fuses out, the draw is gone, put them back in one at a time until you find the circuit with the draw.

Shiny Side Up!
Bill

[TD509EFI]

David,

Sounds as if you've checked everything correctly for the excess current draw. As you've noted, you haven't checked the ECM. I'd disconnect the power for the ECM and check current draw once again. If you find that the draw stops, you could check individual sensor inputs to narrow it down. It's possible one of the ECM sensor drivers is shorted internally or latched "ön" causing the two amp draw. Depending on the circuit, it may or may not set a fault code.

John

[capbuster]

Well, it took a while but I got it! It was related to the PCM. I disconnected the 2 connectors but the drain was still there. Started at the firewall connection as Carl suggested and traced it to the battery connection back to the PCM connection (Blue side). It looks as if either the guy who reworked my harness mislabeled the battery and ignition wires or I just connected them wrong, I had pink to pink (switched ignition). They were swapped!
Pin 20 should be battery and 19 should be switched. After I got them corrected I have no drain at all! Even idles better! I think some of my little issues were related to this. Now the IAC motor is responding better as well.

Thanks for all of the help and suggestions. Hopefully, this will help someone else in the future.