1983 359 Peterbilt 400 big cam _Air/Electrical

@wore out

 

The power for the switched accessories may be staying on instead of working off key switch. Your just gonna have to start unhooking stuff till they go off. Then move the power to a power only with key on terminal

 

When did this start? Did anyone rewire or jumper a wire recently? I have completely rewired my 359 so I know a bit about this.

For the way the OEM built it you have 2 rows of breakers on the passenger panel. The ones on the left are live all the time, the ones on the right are turned on when you turn the key on, by energizing a large relay that is mounted behind the breakers. If no one has done any rewiring, or work in there, I would be inclined to think the relay has frozen in the on position. When you turn the key, you should hear a loud click from that location. If no click, then it may be shorted. Does other stuff stay on when you turn the key off like the heater blower?

Now, if someone has been rewiring, they have not put the line that goes to those buzzers back correctly. If I recall correctly they need to be fed from the switched accessory breaker. Your glove box has a sticker with names and positions.

Best advice is to get the service manual. I got one on ebay for a bit over $100. It has been invaluable for tracing wiring issues. And it also has some very informative air line info, which is also an issue with this old of a truck.

Good luck.