fuse box problems

[unclepuddle]

hello everyone and thank you in advance for your help. i've used this site before becoming a member to figure out some of the eccentricities of the four 1986 cucv's that i keep on the road for my boss. i'm really stuck with this problem though. on a 1986 k30 cucv i have no power to the heater circuit in the fuse box or to any of the other fuses that are supplied by the same circuit. i've installed a self energizing alternator in order to keep it charging but would like to make it right. it's almost like half of the fuse box lacks power. this truck used to be a brush truck for a fire department so the wiring is kind of hacked under the dash. i've eliminated the spaghetti and gotten it back to close to stock and nothing obvious jumps out as fried. on one of our other trucks i see a circuit breaker installed that seems to supply power to those circuits because a portion of the fuse box was melted. i'm trying to see if this is a common problem on these trucks or if anyone has any ideas on where my problem lies. it almost seems like a fusible link or underhood fuse would be the problem but they all check out ok via test light and dvom.(digital volt ohm meter) any help or ideas would be greatly appreciated. thanks and have a great day!

 

[dependable]

One of my CUCVs is a former brush truck that was originally a M-1010 ambulance. The 1010s are weird in their own right and it was hacked up also. I ended up replacing both cab and engine wire harnesses with ones from a scavenged M-1008. They come up for sale here now and then, and there are some people on this forum with parts trucks they sell off of.

That said, I would start by checking where the harness plugs into fuse box on the firewall and be sure there is a good connection there.

 

[unclepuddle]

this one has a generator and air compressor in a utility bed with the pto so i can only assume that it was a service truck for other machines. i am in the process of separating the fuse box right now. thank you very much!

 

[dependable]

Sound like you have an M-1031 contact maintenance truck, for your future reference. Truck chassis usually same as M-1028. The chassis wiring is the same as 1028, 1008 pickups and for the most part the 1009 blazer, if you need to look for a harness.

The utility bed components are specific to the 1031, and are pretty much wired separate.

 

[unclepuddle]

awesome! thank you! sometimes it pays to go straight to the experts

 

[MarcusOReallyus]

TMs (Technical Manuals) are available for download. Free to members in good standing or anybody wandering the Internet that happens to spot the link.