1988 F250 IDI Electrical Problem
 

For the past few years I knew I had some electrical issues with this truck but let it go since the truck was running fine, but now the batteries will not stay charged over night. Some of the problems that this truck have are like when I use the turn signal the oil pressure gauge will move up and down with the flash of the signal, or when I use the electric windows the radio will shut off then come back on. Another thing is the while the heat is on and the higher the blower setting is on the higher the coolant temp gauge moves up. The battery gauge is almost always bottomed out, but this is the first time that the batteries have ever drained over night. Has anyone ever experienced this or heard of this kind of thing happening?

A bad alternator can still charge the batteries while running and then drain them overnight.

sounds like floating ground check all the ground straps under the hood

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broken wires in turn signal switch will do wierd things also

Sounds like this is going to be a B****H to find the ground problem, what exactly is a ground strap and is there more than one. Today i am going to tear the dash open and check ground connections in the cab, hopefully I will find something in there. I was looking at the main ground yesterday and I traced the wire from the negitive battery lead to where it makes a connection to the engine, they were both tight but were covered in oil and sludge, could that be causing it to make a bad connection?

I would clean it just to eliminate it as a possibility. Ground straps are just cables, they are usually bare. I'm not sure if a diesel really needs/has them. I know on gas motors there is one grounding the engine to the frame.

Yea would definatly look at all possible grounds. Your issue definatly sounds like a ground problem. As for the battery drain may be a separate problem but start with all the grounds first.

there are bare braid straps all under the hood see how many are disconnected if its been wrecked they may not be there

there is also one or two under the cab from pinch weld to frame. well... should be.

it could i had that cable split open and was grounding twice like it prevented my other battery to be usable while starting it seem i covered it and it was noticeable cranking power added