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    1999 gmc 3500 quad cab dually

djjdave1's Achievements

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  1. Disconnect main alternator charging wire back to the battery. Disconnect neg cable first, then disconnect positive wire from back of alternator and tape the end of the wire so it can't touch and short out. Then reconnect your ground wire to the battery and see if you still have a drain. Could be bad diodes in alternator. Dave
  2. Do you still have the old oil pressure sender try swapping the old one out see if your problem is the same you may have a bad oil sender Dave
  3. hiya, this is Dave, I have a 99 gmc 3500 4wd crew cab with the 7.4 vortec. I had tranny issues at one point too, found I had some grounding issues. Truck started right up, so my neg to the block was good, but I had found cab to chassis was rotted thru. So you might want to get a braided ground strap from the parts store and go from the block to the firewall. Also check the grounding of where the ECM is located, which I believe is on one passenger fender. There should be a ground wire from the battery to either the inner or outer fender. Again, corrosion/rust could be playing tricks with you electrical system. Do you have the 4L60 transmission? you may want to check the shift box on the shift shaft of the transmission. It may not be sending the signal to the computer that controls the shift solenoids. hope this didn't drive you crazy' Dave
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