I have an `85 F350 with 460 engine. Recently, I noticed that none of the dash gauges were working including the heater blower and turn signals. After making a stop and re-starting the engine all was okay.

The next time the truck was driven it was raining and so the wipers and defroster were being used. They worked when turned on, but then stopped working when the clutch was depressed to down shift going around a corner. Additionally, the motor stalled. This happened several times – all accessories stopped and engine stalled - until the destination was reached. Each time the truck would re-start and everything worked until the clutch was depressed again. But, it did not necessarily happen with every pedal depression, but maybe one out of three depressions. Since then though I have not been able to get it to behave like that again. I have depressed the clutch many times and all is okay. The fuse box is located near the clutch pedal and I have tried moving wires that are associated with it thinking that I might have an intermediate short, but that has not reproduced the problem.

Any thoughts would be greatly appreciated. Two thoughts that I have are the clutch lock out switch, which keeps the truck from starting unless the clutch pedal is depress. The second is a failing ignition switch.

Thanks in advance,

Mark

 

Mark, I agree, it's got to be one of those. Since it does it when you depress the clutch, I'd suspect the clutch safety switch first. Try spraying it with WD-40 and see if that helps temporarily. Better to change it out, though.

On second thought, the accessories aren't connected to the clutch safety switch. It only controls the starting circuit. Maybe it's the ignition switch........?

My daughter had a similiar trouble with the accessories going off. The Mustang ran and started fine, just the fan and various lights and radio would go off. When I replaced the ignition switch, the old one fell apart in my hands.

 

Yes, the fact that depressing the clutch had a direct impact led me to the clutch switch but I assumed it only affected the start circuit. But, what would be the link between the ignition switch and depressing the clutch? Thus, the reason for my post since neither one really made complete sense when you think it all the way through.

Mark

 

Check to see if you are pinching any wires when you push in the clutch.

 

I had a problem like this one my pickup, and it was the ignition key/ switch combo. When it does it again, lightly wiggle the key without turning the motor off. My detents in the keyswitch had gotten where they would not positively put the switch in the correct position. So the key would end up "in between" the positions. I noticed when I replaced the ignition switch, and put wd40 on the keyswitch lock, you can feel the positions it should go in better.

 

Have you got a ground strap running from the engine to the frame? If not, install one.
My 2c: The electrical system is grounded to the engine by the ground wire from the neg. terminal to the engine, usually at the Alt. bracket. The engine is isolated from the frame by the rubber in the engine mounts and the bushings in the rear suspension. It is only grounded to the frame by the gear shift assembly.
I think when you depress the clutch you are disrupting the ground.
Install a ground strap and see what happens.