Electrical issues

[gtptuner]

I have a 91 GTP and I am having some strange issues with the electrical system....

1) the battery is not holding a charge over night and I have already replaced the battery and alternator.

2) the lights on the info center and oe radio seem to surge while the motor is running.

3) the hud only lights up slightly and only once in a while...probably the dimmer switch?

any suggestions?

[Schurkey]

I have a 91 GTP and I am having some strange issues with the electrical system....

1) the battery is not holding a charge over night and I have already replaced the battery and alternator.

Three possibilities.
1. Two defective batteries
2. Dirty battery cases--batteries self-discharge through the conductive slime on the case. The slime allows current flow between the positive and negative posts.
3. Excess parisitic drain through the vehicle. Easily tested with an ammeter connected in series between battery post and battery cable. Anything over 1 amp is excessive; older vehicles may have "0" amps; newer vehicles typically have something like .5 amps of constant drain.

[pocket-rocket]

3. Excess parisitic drain through the vehicle. Easily tested with an ammeter connected in series between battery post and battery cable. Anything over 1 amp is excessive; older vehicles may have "0" amps; newer vehicles typically have something like .5 amps of constant drain.

To back this up, I do the parasitic drain test and pull fuses one at a time to find out what circuit it's on. When the drain stops after pulling a fuse, that's the circuit the drain is on.

[Schmieder]

If your batt is drained, you can test a parasitic leak with resistence between the + and - cables (with out the battery connected). This is a good method IF the short is too strong.

If the resistance is near infinite, you have a parasitic leak. Pull one fuse at a time until your resistance jumps up. Just another way to test for parasitic losses but this method omits the battery.

Reminder, there will be a small amount of draw which is normal. Don't confuse a milliamp draw for a short, the PCM uses power while key/off.

[Schurkey]

If the resistance is near infinite, you have a parasitic leak. Pull one fuse at a time until your resistance jumps up. Just another way to test for parasitic losses but this method omits the battery.

To infinity...and beyond!

How does an ohm reading jump UP from "infinite"?

Seems like a bad idea, because a tiny drain and a huge drain are going to look pretty much the same to an ohmmeter...but I haven't tried this method, so I don't have direct experience with it.