My tj died on Wednesday night and wouldn't start. I had no dash lights or any lights coming on when turning the key. I jumped the car to try and get it home but the jeep would only start if your revved the engine and held the rpms above 1000. I finally got the jeep home and began testing the electrical system. The battery reads above 12 volts with the engine off so we assumed it was the alternator. I went and bought the upgraded 136 amp alternator from autozone and still have the same exact issues as before. Jeep will only start if jumped and feathering the gas pedal, but will dies if the rpm's fall below 1000. I checked and cleaned the battery terminals as well. I am getting stumped at this point. Anyone have any other ideas as the source of the problem?
Well, first off...Your test of the battery only revealed half of it....
If it metered above 12 volts with engine off, then it should try to crank and all lights and accessories shoud work....12.8 volts is considered fully charged with engine off, but that's only half of it.
You had no business buying alternator before you started engine and retested battery...even if you had to jump it to start it, you should have then tested batt voltage again with it running even if you had to gas it to keep it running before buying alternator...So stop spendiong money swapping parts until you do some follw up testing.
Once running, even if you had to jump it, the readings across the batt terminals (in the center of the posts, not at terminal clamps) should meter out well above 13 VDC, up to 14.5.
If you get well above 13 VAC at center of batt terminals with engine running, then alternator is working and battery terminal clamps are tite and clean unfuff to recharge battery and start it.....If not, then shift meter probes to battery cable clamps...if the battery cable clamps show above 13VAC, then clean and tighten clamps where they attach to battery posts and if they or one is a temporary style clamp, then toss it and reattach new new clamp after cleaning and brushing cable wires to shiny clean.
I had my battery die in my 00 tj, jump started and would not idle. Quick post on hear and Jerry pointed out they will not idle with dead battery, trickle charge overnight and she was good to go. On another note the alternators are not internally regulated, they are controlled by the pcm, so if your not charging at 13+ does not mean it is a failed alt.
If the battery is weak the engine will not idle at low rpm. Also, if the terminals are dirty and bad connection, engine will not start and if jumped it will not idle. This has happened to me a couple of times and all it is is the battery terminal connections are dirty. 2002tj has good advise as well.
Yup, and you need to be REALLY careful right now while doing all this jumping or you WILL blow a good alternator.
Before jumping, take keys out of both cars...make whoever is assisting SHOW you his keys in his hands....And make sure vehicles are NOT touching....In other words do NOT have other car running or even ignition turned on when you connect cables or you can blow alternator diodes and not even know it till later when either or both cars won't charge.
Both cars off, not touching, now connect cables, grounds first preferbably to solid engine ground, then pos terminals, then start and rev assist car to well above idle for a few minutes before you attempt to crank yours.