Electrical Problem Where do I start?

[BikerTrash]

OK, I'll explain this as well as I can, the jeep runs like crap when you first start it, if you let it warm up a little it starts running better, but if you turn on anything electrical in the jeep it runs like crap and wants to die, even putting on the brakes, headlights, air conditioner or anything, I dont even know where to start, it was doing this just when I turned on the head lights, so I replaced the switch, and it has been getting worse and worse, the battery is good, the alternator is good. it has been getting alot worse, use to I could drive it about 2-3 miles and it would clear up and not have any problems at all till the next day when I started it cold again. someone please give me something to check or somewhere to start. thanks

[Tractor 68 Boy]

Sounds like you should have it scanned by a dealer. I am not being a smart ass but that is one of the easiest and fastest ways to find the problem.

[Dale Aeppli]

Originally Posted by BikerTrash

OK, I'll explain this as well as I can, the jeep runs like crap when you first start it, if you let it warm up a little it starts running better, but if you turn on anything electrical in the jeep it runs like crap and wants to die, even putting on the brakes, headlights, air conditioner or anything, I dont even know where to start, it was doing this just when I turned on the head lights, so I replaced the switch, and it has been getting worse and worse, the battery is good, the alternator is good. it has been getting alot worse, use to I could drive it about 2-3 miles and it would clear up and not have any problems at all till the next day when I started it cold again. someone please give me something to check or somewhere to start. thanks

HI, FIRST OFF WHAT YEAR, MAKE, MODEL ,ENGINE DO YOU HAVE
DALE [email protected]

[BikerTrash]

IT is a 1990 2 door cherokee with a 4.0.....

[gtmud]

With your engine running, put a digital meter across your battery terminals. DON'T REMOVE YOUR TERMINALS WHILE ENGINE IS RUNNING!) Should read 14 +/- 2 volts. Turn on the headlights, see what happens to your voltage, does it drop out? It really sounds like your alternator is going, enough power to run the engine and thats all. Keep in mind, everything in your Jeep is controled by electrical current. Any charging problems will affect your running condition.

[BikerTrash]

I'll try that, but I have gauges in the dash, and my amp guage never moves, it stays between 13-14 volts regardless of what is on

[glennco1]

Measure your voltage at the battery before you start your rig as well, this will give you an idea of how good your battery is.

You may want to watch the voltage drop when someone starts your Jeep as well. This will tell you how well your battery is handling excessive load.

If the battery is starting to go bad, this will cause your alternator to work too hard and can lead to premature failure.

I agree with gtmud though, I think this is an alternator issue.

[BikerTrash]

OK, GUYS, youve sold me, I am going to pull the alternator off and take it for testing, I think we have a shop here that will do test if for free, and that will be as good a place as any to start. it does get worse the more electrical stuff you turn on, such as the fan for the A/C it runs steadily worse the higher you turn the fan until it will finally die,

sucks I have a 4 1/2 inch lift with brand new 33/12.50's to put on it, but wanted to get this fixed first, thanks alot and let you all know what happens.

in the mean time if anyone else has any ideas, please shoot, I'll try anything

[BikerTrash]

OK, took the alternator for testing, and it tested just fine, man what a pain to get to that thing,

still doing exactly the same thing, any other suggestions?

[IdahoJeeper]

I'm no genious when it comes to auto mechanics, but I am an electrician. What GT and the others are looking at is the fact that as you continue to load down the system, more draw is being put on the alternator than it can handle. The guage on your dash is most likely a VOLT meter, rather than an AMP meter.

Perhaps your local shop could actually measure the amp draw on the alternator and see what it's trying to crank out. There may be some hidden load out there, a short, maybe, too small to blow a fuse but big enough to drag on the system. Then you do what an electrician would do...start disconnecting stuff (pull fuses, relays) until the problem disappears.

HAPPY HUNTING!