98xj98
08-16-2012, 12:42 PM
Need to pick someones brain...
Got a 90 xj that won't charge.. replaced alternator.. no go. Battery load tests good... fuse link from alternator power feed is intact. I got 12v to yellow wire at alternator. According to my repair guide I'm supposed to have some voltage at the tan/blk wire with the key on. I don't have it. I pulled the harness apart and tested all the way back as far as at the cluster (tan w/green wire) where it goes to the volt meter and it has continuity... the other side of the gauge where it draws power from comes into the cluster #5 cavity. According to the diagram it should be keyed power from a 7.5 amp "gauges" fuse. Fuse tests good. Power at fuse both sides. But nothing at #5 but all the gauges turn on and function when plugged in... now I'm lost. my schematic just shoes the fuse going straight to the cluster... the gauge seems to work. It read battery voltage... how does this have anything to do with charging??? My understanding is the yellow wire comes from the pcm to supply exciter current to start the alternator charging. As fas as I can tell the tan/black wire runs from the alternator to the ground side of the gauge for the sole purpose of varying a resistance to ground to operate the gauge?? Alternator should charge regardless of this wire if I'm not mistaken... I'm at a loss HELP!!
Got a 90 xj that won't charge.. replaced alternator.. no go. Battery load tests good... fuse link from alternator power feed is intact. I got 12v to yellow wire at alternator. According to my repair guide I'm supposed to have some voltage at the tan/blk wire with the key on. I don't have it. I pulled the harness apart and tested all the way back as far as at the cluster (tan w/green wire) where it goes to the volt meter and it has continuity... the other side of the gauge where it draws power from comes into the cluster #5 cavity. According to the diagram it should be keyed power from a 7.5 amp "gauges" fuse. Fuse tests good. Power at fuse both sides. But nothing at #5 but all the gauges turn on and function when plugged in... now I'm lost. my schematic just shoes the fuse going straight to the cluster... the gauge seems to work. It read battery voltage... how does this have anything to do with charging??? My understanding is the yellow wire comes from the pcm to supply exciter current to start the alternator charging. As fas as I can tell the tan/black wire runs from the alternator to the ground side of the gauge for the sole purpose of varying a resistance to ground to operate the gauge?? Alternator should charge regardless of this wire if I'm not mistaken... I'm at a loss HELP!!