Comanche Dies With Electrical Load

[CaffeineTripp]

Tested the battery at standing and charging, came to 12.8 standing and 14.7 charging. The alternator relay clicks, though that doesn't necessarily mean it's in good working order.

Any electrical load applied; headlights, taillights, hazards, blinkers, etc. kill the engine.

The clutch master cylinder is leaking onto the fuse box, though I moved it as best I could as I don't have the funds for a new master cylinder right now and I'm not sure which fuses, capacitors, and relays do what on the fuse box as the writing is barely noticeable.

Any thoughts?

[64 Cheyenne]

Myself, I would remove the Neg cable from the battery (with the motor running) if it dies, then I would remove the alternator take it to NAPA, Carquest, etc have it tested. My first guess would be a bad alt.

I definitely wouldn't rule out the MC problem though. Suggest getting a handle on that ASAP to prevent further electrical damage.

Batteries can read a full charge with a multimeter, but not have enough amps in them to do their job. To test a battery a load tester is really the only way to go. A load tester puts a massive amperage draw on a battery for a short amount of time then measures amps/volts left. When a load test is done on a battery, it is done a few times, not just once, this allows a person to see if the battery is/can have recovery time with juice (electricity) left in it.

After rereading I see you have 14.7V charging, you could still be getting 14V out of your alternator, but no amps.

I'd still do the down and dirty, pull the neg cable.

Go from there.

[CaffeineTripp]

Kind of thinking that same way as well with the load tester. I may still bring it to Advanced Auto and get that checked out, but it's still having a hard time driving under load as well at points. I believe the fuel pump to be in good condition, though I don't have a pressure tester, it is sending fuel, in increasing amounts (visually), through the throttle body.

I'm at a loss as to what the exact problem to be, and since this is my DD, I've got to come up with a solution quick. Tomorrow's going to be a lot of testing. Fun in this 10* weather we're having in MN.

[JeffN]

NEVER unhook the battery cable while the engine is running, it could spike and destroy electronics, vehicles without ECU's you could

[CaffeineTripp]

Just got done starting her up again. Fired right up the first time. Turned on the heater, wipers, blinkers, head lights, parking lights, stepped on the brake, put it in reverse. Did just fine. Turned on the hazards and she started to die. Turned them off, ran correctly. Turned them back on, ran just fine.

What kind of weird electrical gremlin is this?

 

As a side note, I believe I read a while back that the blinkers/hazards will make the fuel gauge needle jump back and forth when the lights are blinking because the relay is wired into the fuel gauge?

[CaffeineTripp]

Did a little digging around the positive battery wire's loom. Found this.

 

 

:doh:

Gotta love previous owners and their 'fixes'. Be a while before I can get a new battery wire to supply power, so for the time being I cleaned as much of the corrosion off as I could, loaded it with solder, put heat shrink around it, and some new wire loom. Should hold for quite some time at least.

I still don't know if that was the exact problem, but it sure is a big red flag.