cjk09

what computers would work for my 94 its a 4.0l 5speed? some said a computer from an automatic jeep wouldnt work....and was told that the voltage regulator is in the computer thats what is wrong with mine. Any info or help is appreciated

CCKen

Only computer I could find is for the 1994 only, OEM Part Number 56027890. 4.0, Manual Trans, W/Radio Noise Suppresion.

You could search Google, etc., by OEM part number and see what turns up.

I don't have a '94 FSM so I can't help you on voltage regulation.

What makes you think the ECM is bad?

cjk09

I was told that the voltage regulator was in with the computer on these...sometimes it will charge my battery and sometimes wont im not sure if its the voltage regulator or what...?

CCKen

Are you getting a Check Engine light?

Do you have a voltmeter on your instrument cluster or a generator warning light? What's happening here?

Generally all electrical grounds in the engine bay should be inspected for corrosion, cleaned, and check for security before doing any troubleshooting of the alternator charging system. Also, the battery posts bust be free from corrosion. The battery, field, and ground connection on the alternator need to be free of corrosion and secure.

The battery must be fully charged and serviceable.

cjk09

i have a voltmeter on inst panel reads 12 or under when running. I have refreshed all of my grounds in engine bay and battery terminals are clean and had tried charging it several times and still drains it.and checked all wires on the alternator nothing looked out of place or corroded or broke. Dont know much about electronics if you couldnt already tell hah

CCKen

In that I don't know enough about your '94 XJ to be that helpful I suggest you start a new thread with a title that says "94 Charging System Problems" or some such. It may get the attention of '94 experts that can help you.

In the new thread, make sure you give the specs on your Jeep: engine, trans, etc. And describe in detail what problem you have and what actions you have already taken.

You have an OBD I vehicle I believe, so you should access a code reader and see if you have any stored codes. If you do, state what code(s) you have.

Radi

Have you tested the alternator for proper operation? Those fail more commonly than the voltage regulators.

weebur

Pick up a digital meter and check the voltage at the battery while the engine is running. It should be~13.8 volts, if it's ~12 volts like your dash gauge then I suspect it's your alternator. Not hard to replace, just get a good one so you're not doing it again in a year or so.

cjk09

ok ill go check now and thanks for the info so far

5-90

It do. I'm not thrilled with the idea. You can bypass the integral regulator circuit using any external regulator you like, but know that it will throw a CEL that you can't get rid of (as soon as you clear it, it will come back.)

Ergo, if you have regular vehicle inspections, you will probably fail them. If you don't, I do suggest getting a Code Reader for your rig (OBD-I, make sure you have the Chrysler adapter in your kit) because there are "hard" codes (they trip the CEL/MIL) and "soft" codes (that don't.) And, a persistent CEL/MIL you know about can mask other faults until they become big problems.

However, before you get into anything, any suspect readings on gages at the IP should be verified independently. Funny voltmeter reading? Get out your DMM and recheck at the battery. Funny oil pressure reading? Pull out the sensor and plug in a mechanical gage.

If you're worried about a primary electrical component (Battery, Alternator, Starter,) I've posted a writeup on testing that system - you just need a DMM, a helper, and 15-30 minutes (depends on how in-depth you want to get.) You can search up the writeup here, it's a thread that I've started.

alnielsen

I've had the same issue with my 94. The dash voltage meter reads about 12v, even after the alternator went bad and was replaced.
It starts well. I just figured it was a bad meter and kind of ignored it.

cjk09

checked it last night with meter on my battery when started only 11.5 volts when i let it run it jumps up to where it should be at like 14.5 volts i dont know what would cause that. I have a meter so i can check things just let me know what needs checked. The meter i have is reading what the jeep is reading on the voltmeter so i know its not my gauge.

CCKen

Did a little research into the '94 charging system.

On the alternator you should have a field terminal with an 18 gauge, dark green wire with an orange tracer. As soon as the engine starts you should have battery voltage at this terminal. Power taps off the ASD sense signal to the PCM. The wire goes through several splices enroute from the ASD wiring to the PCM to the alternator. It passes through a dark gray connector near the alternator, then through a splice, before connecting to the field terminal 'B' on the alternator.

Your ASD relay must be working or your engine wouldn't run. No, or low, voltage at this field terminal (B) at start up would mean a bad splice. The splice carries ASD wiring to the ignition coil as well so I would think the dark gray connector is okay.

cjk09

Problem solved.. got alternator off today and took it to get tested ended up it was shot got another and im back in business

CCKen

Good work.