rangejunkie
Newbie
Ok guys, I got somethin funny going on with my charging system..... I think. Truck is a 1993 K1500 with 5.7L. Problem is when i have the a/c on high amd recirculate, lights on (dim or bright doesnt matter) the voltage on the truck drops. Tested alternator, tested at local parts store said alternator was ok. Until tested when truck was in gear, then said regulator failed. Just replaced with new alternator. At idle speeds, my scan tool says it's sitting at 685 to 700 rpms. All voltage with all accessories and lights running is good 14.5v. As soon as I put it in gear (reverse or drive) rpms drop i guess due to aditional load. Except voltage drops unless I turn one of the following off: lights, recirculation, or fan off of hi. Once I do that voltage returns close to 14v. This all happens while sitting still in gear. Driving operates fine at 14v. At idle in gear it has dropped as low as 12.4v. I have tested my ground wires with power probe and get good continuity indications. Did clean battery to block and battery to body grounds. On my alternator wire i do get 3.4 k ohms, i believe this would be a high reading i did parallel a jumper cable with it and no nchange as far as voltage drop. I'm starting to lean towards replacing the positive battery cable since it is original and showed some corrosion in the molded plastic before i cleaned everything. Imalso starting to wonder if it might be a TPS or IAC issue, should there be compensation with engine rpm when accessories are turned on while in gear. No check engine lights or codes. Battery was tested as well and showed to be good too. If I can get correct voltage readings or know what to look for on my scan tool I could verify the TPS and IAC are working. My scan tool is a snap on red brick MT2500. Don't really want to load a parts cannon. Any help is appreciated.