1999 Jeep Cherokee Alternator Replacement

1999 Jeep Cherokee Alternator Replacement

Our 1999 Jeep Cherokee has over 270000 miles on it and has recently been having some odd problems with voltage. On occasion, the volt meter would drop to 9 and the check gauges light would come on. Stopping the Jeep and restarting would normally clear it right up. I assumed it was a gauge issues and not really a voltage problem. Testing the battery with a VOM always showed it to be fully charged.

However, a couple of days ago while Janice was driving, the voltage dropped and stayed down. When she stopped, the Jeep would not restart. The battery was dead. Jennifer had to jump start her from her Jeep.

Later, while I was driving it, it died in traffic and I had to push it to the side of the road. I retrieved it on the trailer and took it to the shop. Testing showed the battery completely drained.

I put the charger on the battery and began pulling the alternator. Removing he alternator from the 99 was similar to the earlier models but with a couple of differences.

First, the field wiring connector is a plug in rather than bolt on. It took some force to release the clip but it pulled right out. The min lead connects just like the others with a 10mm nut on a stud. Be sure to disconnect the battery before messing with this nut.

Next, I collected my 15 mm socket and 9/16 socket knowing I would need both. Working from below, I removed the bottom bolt that passes through the alternator boss. I then loosened the 15mm bolt next to it. I then loosened the 9/16 nuts that bolt the bracket to the block. They only need to be loosed a turn or two not removed.

Then, I removed the long bolt that passed through the upper alternator mount. Both ends of this bolt require a 15mm. I found it easier to hold the bolt and turn the nut due to the fan being in the way. I found one position of the fan that allowed the bolt to come all the way out.

With the two bolts out and the bracket loose, I slid the alternator up to loosen the belt and then to the side to separate it from the brackets. Mine was stuck to the brackets with some corrosion so I had to use a pry bar to break it free. Once the alternator was free of the bracket, I twisted it to find just the right angle to bring it down past the frame rail and oil pan.

With the alternator out, I noticed some corrosion on the field wiring terminals. This may have been the cause of my intermittent troubles. However, I elected to replace the alternator anyway. It tested “good” on the AutoZone tester, but with its age, I decided to replace it anyway.

Installing the new alternator involved finding the right angle to slip it up past the bracket and lowering it back into place. It is possible to reinstall without adjusting the belt tension, but I chose to install a new belt at the same time as well.

I began by slipping the lower bolt in place. I then rotated the alternator to line up the upper bolt. Then, I found the right place to put the fan and slipped the upper bolt in. I tightened the upper and lower muting bolts then snugged up the reaming nuts and bolts that I had loosened but not removed.

I put the main wire back on and then plugged in the field wiring. I then put the battery cable back. I then threaded in the new belt and adjusted the tension.

The Jeep started right up and the voltage read correctly on the gauge. I test drive indicated everything was back to normal. We had experienced some belt squeal when the AC was first turned on but with the new belt, that was gone as well. After the test drive I checked the battery and it was at 13.7 just like it should be.

2 Replies to “1999 Jeep Cherokee Alternator Replacement”

  1. Good write up. Thank you for the details and clear explanation. I have a ’99 XJ with 180,000 miles and have been experiencing the same situation: volt meter is either low or zeroed during operation, followed by a few successful starts. Then, I finally failed to start when the battery drained completely (I couldn’t even power a turn signal while driving), due to lack of alternator charge. My suspiscion has been that the alternator wiring is loose or corroded to the point of experiencing broken circuits sporadically. I’ve gotten into the habit of reaching underneath the Jeep and wiggling the alternator wiring to maintain a connection whenever I see the zeroed voltmeter and Check Engine light. This gets the alternator charge back to the battery and the system gets charged – reaching under is a temporary fix, not something I’d like to have to do on a date, ha! I am planning on correcting in the same way that you have: replacing the alternator, due mainly to its age and secondly due to recent exposure to varying charge-loads (drained battery recharges, then high charge rates, and open/closed circuits at the alternator).
    What brand alternator did you use as your replacement?

    MJ (99 XJ Sport, 4.0L, 180k mi, 4.5″ Rough Country suspension lift)

  2. I picked one up at autozone so that I would be able to swap it while traveling if necessary.

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