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97 f250 hd - 5.8 auto. Battery was getting low. I noticed by the gauge but also by turn signals slow, blower slow, etc. took it to get it tested. Said battery was low and alternator only putting out 11 amps. Charged battery and installed rebuilt alternator. Still going down after two days. Test shows battery ok just needs charge, and alternator only putting out minimal voltage. Changed battery terminals and same issue. Everything works fine until battery starts going down. Only thing that’s different is that I changed (last week) the gauge cluster because the trans was going a bit haywire , and I tried to change cluster to “replace” the trans control (vss I think?) and it worked a lot better. Could that be the cause of the alternator not charging as it should? Oil pressure gauge seems to be reading a bit lower as well since cluster change. Any ideas? Thanks for all the help you guys provide!
I found another 96 cluster from an old truck I had so I decided to do that. Plugged it in, and noticed the differences in the 92/93 one I had installed. Same thing - charge gauge trading low and battery not being charged by alternator. I guess it’s possible the new alternator is bad - should I take it off of the truck and have them bench test it? Then at least in theory that would tell me if something is wrong with the alternator or somewhere on the truck. Is there a fuse somewhere that might be bad?
Well after some more digging, and after the diagram you guys sent - I saw some loose wiring on the plug into the alternator - I’m sure I wiggled it loose when removing it - plus the plug was loose itself. I found out by pushing it in while running and the idle lugged down again as the alternator was “working” - and for everyone’s info, autozone sells the EXACT plug to replace yours instead of paying big $ at ford. Thanks guys!