Alternator woes

[90XJay]

97 xj, 5 speed. Alternator appeared to be crapping out. 2 weeks prior my 00 was doing the exact same symptoms of gauge showing 14, then 12, then 9 after about 5 mins of running. On the 00 I didn't have time to test when I had finally grabbed my meter from work (was doing it after I picked up my meter) so I just put in a new alt and it has been fine since. So now my buds 97 does the exact same thing. We decide to do the 136 amp alt at the same time. Install goes fine. Redid the wiring (neg to chassis, neg to block, block to firewall, alt to starter, alt to fuse block with fuse, pos to fusebox) with 4 awg (I work at Best Buy doing car electronics installs so I have a good grasp on the wiring side). Took it for a test drive today and seamed great. Power windows going up better, sits at 14 and all was good. Then my bud goes to leave with the jeeps and after 30 mins of driving it goes back to the same symptoms and he gets it back to the house as the battery gets very low. Has new battery, alt, wiring. This time though he said the speedo stopped working and the fuel gauge also acted up. I fear this could be an ECU issue. Tried some searching but haven't come up with much. I have alldata at work and was going to start chasing wires but I figured I would ask for some pointers/common places to start. Thanks for any help.

 

[CharlesS]

My first question is why a cable from alternator to starter ? Should be battery to starter....
If you truely did connect the alternator to the starter; there is a problem there....
Have you checked the voltage at the charging stud on the back of the alternator with the engine running?
If the alternator voltage is 13.2-14.8V; then I would say the inline fuse you installed that acts as a fusible link is either blown or connected wrong.

 

[joe_peters]

My first question is why a cable from alternator to starter ? Should be battery to starter....
If you truely did connect the alternator to the starter; there is a problem there....
Have you checked the voltage at the charging stud on the back of the alternator with the engine running?
If the alternator voltage is 13.2-14.8V; then I would say the inline fuse you installed that acts as a fusible link is either blown or connected wrong.

Agree--no alt to starter hookup.

Did you bother to load test the battery with a carbon-pile tester, 1/2 CCA rating for 15 seconds, voltage not to drop below 10 volts?

Check the battery temp sensor (located under the batt) for corrosion.

 

[90XJay]

Sorry yes to pos to starter, was a long day. I removed one cable at a time replacing it with 4 gauge.

 

[90XJay]

Battery temp sensor appeared fine when I removed the bat box to help in getting the alt out (I usually pull it for more room). I did not have a working meter with me (bought one for the house and dead out of the box... cheap harbor freight pos had a dead screen but could get audio chirps for continuity). Fuse checked fine with continuity.

 

[90XJay]

So turns out the new alt had crapped the bed. For anyone searching/has a similar issue there are 5 connectors on my alt (97 style). The 4 part connector has 2 grounds on the ends and then the 2 connectors in the middle, one should check the voltage of the system (checking the ASD relay circuit). The other will check 0-12 volts depending on if the PCM is telling the alt to charge or not. Mine was .4 volts which according to Kastein means my PCM was telling the alt to charge full bore. Turns out the remain/new alt from Advanced-Autism Parts crapped out after 20 mins. Swapped it out and it's charging fine again. I did also clean up all the grounds before hand as well and put dielectric grease on all my connectors too before swapping the alt.