charging problem with my xj...

Ok my 97 xj 4.0l automatic has a mind of its own... Most of the time it will run at 14volts on the gauge sometimes it will run at 10 or 11 volts on the gauge then other times it will just completely drop to 9 volts and stay there. it happened to me about a month ago when it left me stranded 2hrs from home got a battery and made it home on battery power but gauge stayed at 9v the whole time. left it parked at my house and 5days later turned it on to work on it and it started right up and the gauge read 14v up until yesterday when it dropped to 9volts again and now its just running at 10volts right now. Has anyone had this problem before? Maybe the voltage regulator in the alternator is going bad? I also heard someone mention the voltage reg is external on cherokees is that true? I am open to suggestions i just want my jeep to run normal again. thankyou for any help and suggestions you may have.

I had similar issues on my 91 4.0, I even broke down and took it to a shop the specialized in automotive electrical issues. only to have the issue reappear about 3 hours down the road and 800 miles from home. The issue for me was insufficient ground from battery to body and insufficient wire from alt to power box. Read this article http://www.olypen.com/craigh/charge.htm I did it and haven't had anymore problems.

ya its like it has a mind of its own lol itll be just fine for a few weeks then think everything is ok then ill take it somewhere and get stranded... but i will definately check that out thankyou and hope it works cause i was about to break down and take it to a shop also or replace the charging system with all new parts and cross my fingers lol

Check grounds, and then make sure you have a long stick or piece of pipe, etc. with which you can hit the alternator. If the problem recurs, leave engine running, get out and bang on the alternator. If the voltage pops up, your problem is likely the brushes.

We seem to be getting a lot of these "intermittent charge" threads in the last few months. Perhaps it reflects the aging of the fleet.

The regulator on these is built into the engine computer. Rarely goes bad. Hope that it doesn't ($$$$).

was there a conclusion to this problem?

I have the same thing happening to my 01 XJ as the OP described happened to his. However, I do not see what he did to fix whatever was wrong. I had my alt tested and came back strong at 3 different places and I have a new red top Optima..

Looking to sort this out and saw this post, hoping the OP figured it out and can share.

Check grounds, connections etc. Make sure they are all clean and a coat of grease doesn't hurt.

and of course... http://www.olypen.com/craigh/charge.htm

Have the battery and alternator Load Tested. Worn alternator brushes can get sticky and not make full contact. If the alternator tests good, but you still have charging issues, suspect the brushes.

Faulty wires or poor wire connections will have high electrical resistance.

Perform routine maintenance of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Do the same for the grounding wires from the starter to engine block, and from the battery and engine to the Jeep's frame/body. You must remove, scrape, and clean until shiny, the cable/wire ends, and whatever they bolt to. Jeeps do not tolerate low voltage, bad connections, or poor grounds.

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And, the Voltage Regulator lives inside of the PCM. For testing, use a shop that rebuilds Arlternators as your local slap and dash parts store will put it on hit it with a quick load and pass it. Your problem is intermittent and will require better testing. Test after cleaning all of the connections.

Tim_MN is absolutely correct about the Heep not tolerating low voltage. No Fuel Injected Engine tolerates low voltage as the injectors will simply stop firing.

Hey Tim! I lived in New Hope for 2 years (Summer of 95 to the Summer of 97) working out of an office located in Edina. So, Hey Neighbor!