Recently acquired ‘81 Kodiak single axle dump with air brakes. PO said new clutch and rebuilt transmission 5 speed with 2 speed rear. Has over 200k miles, my problems are electrical and I’ll be posting issues I’m having. I bought it online auction, when I picked it up PO mentioned the only gauges that work are oil and air brake pressure (which is good). No tach, no speedometer amp meter etc. Only just started to mess with as it runs good. I’ve never worked on something this old lol but I noticed that: #1 the alternator has been replaced with single wire and it isn’t putting out. It has tested for good ground. #2. The 2 rows of 11 spot junction on drivers side under hood wires all ohm as ground and I’m guessing that isn’t supposed to be as the wires are assorted colors… There is a mess of wires under dash. Looks like an add on turn signal switch so all those work, parking lights and brake lights work. I’m guessing they got wired around that 2 row junction box. So besides liking to pop out of 2nd, no alternator, no dash gauges… it runs great lol. Anybody familiar with this vintage truck? I bought the 3 manuals I could find for 1981 medium duty trucks but they don’t even cover the fuse box under dash. And even though the cover says 1981, it references 1980 in the book. I’m guessing gonna pull each wire 1 by 1 off the under hood junction to find what is causing the grounding issue… Any other help will be appreciated. I’m guessing this will be mechanical speedometer so kinda surprised it isn’t working.
Nobody has any info on this truck? I see the tach sender on the front of the engine but don’t know if this truck uses that as there doesn’t seem to be anything attached to it (wires etc). Just the mechanical part. I’m wondering if Chevy used another sender. Gonna tear into dash this week I’m off and start tracing wires and what not
Originally there was a plastic flap that covered the terminals on the firewall. That flap had the wiring legend.
@Willie B has a truck very similar to yours, he may be able to help.
Same basic truck & free shipping. * 1981 GMC Brigadier Foldout Wiring Diagram Electrical Schematic Heavy Truck J8 J9 | eBay This is the original wiring diagram printed by GM for dealer mechanics. You can follow the wiring in your truck from bumper-to-bumper. It will help you to understand connector configurations, and locate & identify circuits, relays, and grounds. Although the schematic is in black and white, the... www.ebay.com