[udamann]

Ok here are the symptoms. My voltage gauge only reads 12 volts when I start it up after a couple of minutes it drop all the way down on the gauge and my check gauges light comes on. I haven't noticed any thing odd as far as the battery seeming low or anything. I pulled the altenator and had it tested and tested ok, I also checked the connections at the battery and looked for anyting loose or corroded. What else could it be? Maybe the battery? The guy at parts store said something about the voltage regulator being part of the computer and that they go bad...is this true?

[growli]

I'm having the same problem with my 97. When the voltage gauge drops to zero, I hop out and put an analog meter on the alternator and get over 13 volts. When I turn the key off, and start it back up the dash gauge reads 12 again but will soon drop to zero. I removed the alternator and it tested fine (never been replaced in 187,000 mi.)

I cleaned and sanded all the grounds. Battery temperature sensor wires were pinched between the tray but appeared just flattened and not broken through. I did have a code 44 (BTS) which has been cleared in the pcm.

The car will die after a couple of days of this and will only go a couple of hundred feet before dying again after a jump, so I assume the battery is being drained and not being recharged.

Any other ideas would surely be appreciated.


100 degrees before noon on another dog day in Texas!

[JFM626]

Yes the voltage regulator is unfortunately within the PCM, and if it is faulty you will need to replace it. You also need to do as "growli" did and check your battery sensor. disconnect the wiring harness at the sensor, hook up an ohmmeter to the two wires coming from the sensor, and check resistance. It should be around 10,000 ohms. If not replace the sensor.

[growli]

JFM626,

I did check the resistance at the BTS and got only 5000 ohms. Do you believe that could be our problem?

Thanks.

[Jerry Bransford]

Did you actually remove, clean, and then reinstall and tighten the battery connections? Bad connections, even though they may look good, are way ahead in the lead of likely causes of the symptom you're experiencing.

The voltage regulator on the ECM would be the last thing I'd suspect.

[growli]

I cleaned and removed the connections at both ends. Grounds and positives. I've tried three different batteries. I would hate to blow $120 on a new alt if it is showing 13v on my cheesy voltmeter.

The alt was tested off the jeep. They said it was charging okay, but the bearings might be going out.

It was a brand new autozone so I assume their machine is new too.

Thanks.

[JFM626]

Without a doubt poor electrical connections (both grounds and hots) are the #1 source of charging problems. If after checking and cleaning all your battery and alternator connections, you are satisfied that they are not the problem; then you need to go deeper. When you take your alternator off to be tested at a shop, it is tested for output under load using an external voltage regulator. You need to get it tested when it is in the vehicle and under actual operating conditions. Most shops are capable of doing this. Keep in mind that you already know that the alternator is working on a test bench, so any problems that do show up will be in the Jeep itself. The voltage is controlled by opening and closing a path to ground. Unfortunately I do not know where this particular ground is on your Jeep but I would look for grounds coming of the PCM and make sure they are good and bright. Be sure to disconnect the battery when cleaning any grounds that may be associated with the PCM. To answer your question about the BTS. It could be part, if not all of your problem. I don't know how much a new one is, but the resistance should not be beneath 9,000 ohms. Check the new one before buying it though.