dhoge88

So a bit of a backstory...my first alternator died back in may so i replaced it with one from autozone. on thursday the newer alternator died. what had happenened is there is a wire that goes from the alternator to the fuse box. this wire is attached to the alternator via a stud on the alternator surronded by a plastic guard. this stud actually melted off and melted the "o" connector on the end of the fusable link wire. so i kept the fusable link wire but soldered on a nice 4 gauge wire with a new "o" connector on the end. then installed a new alternator from autozone. this all happened on thursday. so friday and saturday it ran great! on sunday night on my way home "20 minute drive" my battery gauge spiked all the way up and the check engine light came on. monday morning (today) i took it to advanced auto parts and had them check the battery and alternator. both checked out fine. no sooner do I leave the parking lot and the battery gauge spikes back up for 30 seconds at a time. It will spike to 19 when i accelerate but then goes back down to just about 14 when i keep a constant speed or idle. for a few seconds all my gauges went flat too. also now my transmission doesn't seem to want to downshift. I have to manually shift it to 1st at every stop sign or red light, the shift back to "drive" once i get going. does anyone have any idea what could be going on. I've looked up similar problems. some say check grounds, could be voltage regulator aka computer is shot, but I'm not sure what exactly the issue is. this is my DD for my first full time job out of college so I really need to figure this out fast! thanks in advance!!!

also tested the on off on off on trick. it threw codes 41 and 46.

1997, 165xxx miles, auto, I6, country package

Lowrange2

What P codes does it give you on a code scanner?

CCKen

I almost hate to get into this because the '97 charging system is sort of in la la land compared to <97 and 98>. I have a '99.

First, I wouldn't trust autozone. They may have given you the wrong alternator (twice). If you can cross reference it, the OEM part number of the 97 alternator is 56005685AB, Rated SAE Amps 119, Min test Amps 90.

Code 41 is a fault in the alternator field circuit. There should be two field wires at the alternator. One provides battery voltage to the alternator field from the PCM and the other gets a cycling ground signal to the field from the voltage regulator in the PCM. The cycling ground to the field controls the strength of the rotor magnetic field, thus the strength of the alternator output. Code 46 indicates a battery overvoltage (really!)

If the PCM cycling ground wire shorts to ground it may cause the alternator to give excessive output. These two field wires are probably in a wire loom that is coming off the alternator, and close to it. Perhaps you should unwrap the field wires loom completely as far as you can go and see if the wires are chaffed together or to ground. This not saying the wires are not chaffed somewhere else.

The alternator (should) be grounded at one of the ignition coil mounting studs (there will be other ground wires here as well - including the PCM and Transmission Control Module). The other stud is a ground point for the battery. Examine these ground connections by detaching them and inspecting the terminal ends for corrosion. Clean and reattach securely.

The battey temperature sensor is also involved in the alternator/battery charging rate. It signals the PCM with battery temperature data. The colder the battery temp the higher the charging rate will be. Cold temps will create a high resistance in temp sensor and a lower voltage signal to the PCM. If the PCM consistantly sees a 'cold' battery it will keep the charging rate higher. Just some data to keep you occupied.

I'm trying to figure out how that B+ connection on the alternator melted without blowing the fusible link. It may have been a loose nut that secures the B+ wire to the alternator and not a shorted wire to the PDC bus bar (?).

Check to see if you have the correct alternator for a 1997 XJ at all vendor websites. Use the OEM part number as a reference. Compare what Idiotzone supplied you with the other vendors' alternators.

Examine all fuses in the PDC and the JB now that you've now lost the TCM.

The PCM could be smoked. PCM's DO NOT like voltage spikes.

dhoge88

thanks for the quick reply. i'll check everything after work today and reply back. hopefully i make it home in one piece!

do you think the pcm caused the voltage spikes? or do you think the spikes were part of a different problem?

CCKen

Spikes would come from an external source.

Did you remove your battery and have it tested at a shop/store?

You should remove the battery and alternator and have them benched checked. Maybe have them checked at two different shops/stores.

dhoge88

so on the way home yesterday i stopped at auto zone and picked up another alternator, swapped it in, and haven't had a single problem since. i hope this one holds up because the previous one only lasted 3 days. crappy autozone parts........