NWhunter

So I got an issue with my electrical. I went through some good size puddles out wheelin in my cherokee. Its a 1997 Jeep Cherokee 4.0L I6 and the alternator is at the bottem(Didn't take that into consideration when I was rumping in puddles) Now I got a charging issue. My battery wouldn't charge. So I took the alternator out and took it too the auto parts store to have it tested. It reads 14.4 Volts. So I took the battery in, it came back bad. I replaced the battery and the new battery (used from junk yard) and had it tested. It came back good. The jeep starts but runs at a high idle (around 2k RMP). The check engine like is on, and the code comes back as bad TPS. I tested the alternator while on the rig by running the hot post to the battery, Same for the ground to by pass the cars computer. No differance in the charging. The battery gauge on the dash board read 9. I'm stumped! Any ideas?

Radi

What voltage do you get with a DVM connected directly across the battery with the engine running?

Also check your O2 sensor connectors for water or crud along with any other sensor connector that may have gotten wet. Several sensors share the same +5V supply from the PCM. A problem with any one of them causing that voltage to drop low can show up as a "problem" with another sensor.

NWhunter

about 12 volts, But the battery is slowly draining with the rig running, faster with stuff running like radio, fan, lights ect...

NWhunter

basically, the alternator won't charge the battery, even though a bench test came back as good (14.4 volts)

Radi

Hrm... The only thing between the Alternator and battery is a fusible link. The Alternator output and battery are tied together at the PDC. If everything there checks out, could be the PCM isn't providing correct field voltage. Drawing below: