Headlights on = voltage drop 'til battery is near dead.......

[billyrb]

Ok, I found a few other posts where the person has similar problems to what I am experiencing, but there aren't any responses as to what they found or what was done to fix it. Here are their posts:

Originally posted by AMX factor:
Ok everything is fine with the alternator charging the battery, belt is good and tight no slippage, all wires appear good. Normal driving yields at least 13 volts(tried new gauge same reading). So basically all is fine until I flip on the headlights then the voltage draw drops the gauge to below 10 volts. Headlights only do this, park/running lights don't do this. All lights are functioning. Any ideas where to start? Bad head light, fusible link(where?), alt dying, batt dying?

Here is the second post:

Originally posted by Treadted2:
My charging system works fine, EXCEPT when I turn on my headlights. It drains EVERYTHING! If I have my headlights on, my tranny in gear and I am idling, my charging system SUCKS! My volt meter goes way negative, and everything dims down and runs slow. If I have my A/C on and my headlights on, it really sucks! My blinkers won't even blink! They just turn on, and stay on! What's the deal? I have already replaced the Alternator, but it didn't help. Any ideas??

I have this same problem, and will start looking at the wiring tonight. I just wondered if:
a. Has anyone else experienced this problem?
b. What did you do to trace the problem down?
c. What did you find was the problem?

As always, any and all help is appreciated. Once I find what my rig's problem is (okay, I'll narrow it down to just this problem), I'll post a reply with what it was and what I did to fix it.

[graham]

Ryan not sure of the outcomes of those post, but can only suggest either Alt is dickie or there's a short on the light curcuit. Check Alt output, 13.5v to 14.5v. Should be around the same figures with lights on. Maybe a tad lower allowing for draw of lights. If not suspect Alt.
What lights are burning when you switch them on? Start isolating each curcuit, fog's, Hi beams, low beams, park lights and number plate lights. A bit trial and error but electricity is not like water. You just can't see where it leaks easily.
Best of luck.

[pb]

I'm not sure if this will help much, but on my 75, I put in a relay for the headlights and that has actually showed a positive charge, compared to the negative charge it showed before the relay was added and the headlights are on.

ON my 95 C1500, the headlights and blower put a drain on the battery when at idle. I replaced both the battery (2x) and alternator. I was told that at idle the CS130 alternator doesn't put out much at all for charging and all of the accessories compared to what it puts out at higher rpms.

Do the newer Wags have relays for the lights and blowers? I'm assuming that they do, maybe look at those first.

[billyrb]

anyone?

[oldyellowwagoneer]

Check out the connections on the ampmeter, check that the engine, frame, and body are all grounded to the battery and each other, and finally check and make sure the headlamp switch is grounded. it grounds itself at the dash hole so make sure the metals not corroded and there's no paint then tighten the bezel tight. Theres also a last possibility and thats the wiring harness that runs to the dimmer switch,it may be rubbed through and shorting on the floorboard. Hope this helps, Dennis

[Frankenstien]

No Idea why but when I took my engine in for the rebuild it did the same thing. But when I got it back nothing. Holds solid at around 13.5 to 14v . I dont know if they tighened the belt better or cleaned the connection but it just works better.

J

[billyrb]

I might have found my problem.....I'll test a little more today / tomorrow and re-post the results.