jkshavoc

Im running electric fans on my jeep and everytime i switch them on the volt meter drops big time almost to the red. I have relays for the fans and ive had them for about 4 years and never had this problem until recently, now even if i turn the headlights on the meter goes way down. do you guys have any suggestions what it could be? its driving me nuts

solderjunkie

It sounds like the system is low on amperage. When you consume the last available amperage, the voltage will drop as well... they are proportional.

If you have a digital voltmeter, read on:

You want the voltage to be above 13 when it's loaded. We'll start at the battery and work through the system.

Start your Jeep and turn on the headlights and fans. Check the charging voltage at the battery. Check at the center of the post, not the terminal. Then check at the terminal-ends... if the voltage is different, you have a high-resistance issue with the battery connection.

Check the charging voltage at the alternator post... if it's different, you have a high-resistance issue in the charge wire.

Check the body and block grounds: put the voltmeter leads to the block and the battery, then to the body and the battery... we want less than 0.5 volts.

Write down your voltage-findings and post them here. We'll work through it.

jkshavoc

thanks ill check this. Ive changed alternators twice now thinking it was that, hopefully its the terminals.

solderjunkie

Even if you have a charging system problem, it's rarely the alternator... usually the issue is either the PCM or the wiring. The regulator is in the PCM and there is a "voltage sense" wire to the PCM for the regulator.

Jwally12

I'm wondering if I have a similar problem with my 99 cherokee. Since December 2008, My car feels like it is going to stall but doesn't or it sputters and sometimes doesnt want to go almost hesitates while I'm driving it. It will do this really bad for a couple days, but then for weeks it will be perfectly fine. I had the Fuel system checked with a pressure test and it came back fine. I also replaced the O2 censor. But that doesn't seem to help the problem...any ideas if it has anything to do with the internal computer or what. Its just getting on my nerves now I want to take it over sand this summer but I don't want to worry about getting stuck out there.

solderjunkie

Start a new thread, homie.

mike37

The regulator is in the PCM ???

solderjunkie

If it's not a Renix, it's in the PCM.

mike37

never herd of an alternator with an external regulator

jkshavoc

forgot to mention its an 89 so its a renix.

JeepingDan

I had some issues like that on my 88 after working two full days and only being able to mess with it at night I found some bad connections in the plug on the driverside firewall. I took it apart cleaned it up all nice and everything works like it supposed to now Not saying that's your problem just hope I can give a good lead. Good luck