I'm having electrical problems with my windshield wipers on my 1991 cummins. when I put in the proper 20 amp fuse the windshield wipers will work fine for a couple minutes then the fuse will blow out.but when i drove 10 miles without turning the wipers off it worked fine until I turned them off and on again, then the fuse blew again. Sometimes it will blow when I turn on the headlights and other times it is totally random. I'm hoping this is an easy fix and any advice would be appreciated. Thanks

 

With most electrical issues, the first thing to check are grounds. Check the small grounding strap on one of the 3 screws that hold the motor to the firewall/cowl.

 

Ground strap looks fine, I also disconected the wiper motor, replaced the fuse then turned key on and it still blew the fuse.

 

You have a short to ground somewhere. Take the plastic off your coloumn and start tracing the wires from the fuse box to the multi function switch then to the bulkhead connector. Then underhood from the bulkhead to the wiper motor. If its blowing the fuse with the multi function switch off the short should be between the fuse box and the switch

 

The only other thing on that circuit is the a/c clutch. Is your a/c or defroster on when the fuse blows? You could just unplug the a/c clutch, replace the fuse, and try it.

 

I tried unpluging the a/c and it didn't blow the fuse. The a/c isn't charged, would that have any effect?

 

yes it would as the compressor for the ac could be bad and grounding out the circuit when it is plugged in or a more remote possibility is the additional amperage of the two together could be overloading the circuit on some trucks the air conditioner comes on when the defrost is turned on .

 

Good catch! I never even thought about anything else on the circuit

 

So should the A/C comp come on even without being charged? and yes the defrost is on when it blows

 

With no charge in the system, the clutch on the compressor will not engage. The cycling switch stays open.

 

Ok I unplugged the AC and it seems to be fine now. Fuse hasn't blown for a couple of days. I don't understand why that would fix my problem as the AC isn't charged, could the low pressure switch maybe have a short? Anyway to check the switch?

 

Your a/c clutch gets it's power from the wiper circuit. Any time the key is in the "on" position, the a/c clutch has power. The clutch is applied only when the ground side of the clutch circuit is complete. The path from the clutch to ground goes through the low pressure switch, the thermal switch, and the mode selector on the dash.
Actually, I suspect that the coil in the clutch is likely shorted internally. If this is so, the a/c or defrost wouldn't need to be on for the fuse to blow. All the switches after the clutch are on the ground side, so even if they were all bad, none of them would cause the fuse to blow.

 

Hey guys lots of great help here, Looks as though my problem is with the AC clutch Thanks again for all the great help. this forum gets better and better with age.

 

this is awesome,,ive had my wipers on a toggle switch for over a year now since my ac pump locked up but i never thought about it being the cause,,,someone jammed a screwdriver under my steering wheel and messed up the wires so i thought that was the problem,,,but after reading this i unhooked the ac pump and now every thing works again thanks alot guys only problem is now when the wipers turn off the wipers go up instead of going down,,,guess ill have to take the cowl back off and look at every thing again..thank you guys again for all the help and ifo you all put on here...