I have a 98 TJ, w/4.0 engine. The check gauges light has been coming on after starting. When I first start everything is fine, the dash voltmeter reads approximately 12V. After 2-3 minutes of running, the voltmeter goes to zero. All other gauges read ok, the jeep seems to run ok. I have replaced the alternator last Oct. with one from a Durango for higher amps. I put in a new battery yesterday, since mine was 8 yrs old. I still am having the same problem. I checked the conections to the alternator and everything is secure, though some corrosion.
I had the engine scanned and rec'd error code P0463. I also had the auto store run a battery/alternator test, with the alternator still in the jeep. Battery/starter test ok, charging system test gave no voltage.
Another issue before this, I keep blowing the fan fuse,for the HVAC, when I turn it on. Not sure if this is related. When I replaced the fuse and turned the ignition key on, but not the engine, fan seemed ok. Once I turned the engine on and tried the fan switch, I got nothing.