BJ40 Rear heater wiring

[bblawless]

Hey everyone, I’m slowly piecing my bj40 back together for the winter and I’m trying to get the heating dialed. I swapped the tub last season and removed the rear heater and I’ve got the coolant lines hooked up but I’m having trouble with the wiring harness. The rear heater fan worked when I removed it.


So there’s three plugs that come off the harness. One goes directly to the heater itself, the other goes to the driver side seatbelt and the third I haven’t found a spot for. It’s got enough length to reach the heater but the memory of the wires suggests it goes towards underneath the dash? It’s hard to tell. I haven’t found anything obvious…

So with what I have plugged in now, the fan won’t turn on.

Truck is a 1979 bj40 (Canadian) with a B motor.

I’ll post photos below of the harness and the “red wire plug” that I can’t find a home for…would appreciate if someone could shine some light on this

Cheers

 

[charliemeyer007]

What does your wiring diagram show? I think the heater has a 2 speed motor - so 2 wires for sure and maybe a 3rd for a ground. On the dash a 2 speed switch, one would have a resistor to drop the voltage to low speed. This should be on a fuse in the main box.
Make a fused jumper wire and test the fan. I'm thinking the fan motor is 12V but I don't know that.

 

[bblawless]

What does your wiring diagram show? I think the heater has a 2 speed motor - so 2 wires for sure and maybe a 3rd for a ground. On the dash a 2 speed switch, one would have a resistor to drop the voltage to low speed. This should be on a fuse in the main box.
Make a fused jumper wire and test the fan. I'm thinking the fan motor is 12V but I don't know that.

I don’t have a diagram handy but I’m almost certain the rear fan heater only worked on the “high” setting…I’ve found similar info on other threads

 

[charliemeyer007]

Well there you go. Break out the volt ohm meter and get to testing. Back in late 80's I had my Haynes wiring diagram blown up 24x36 inches - much easier to read big print. On the back I wrote tune up/torque spec's part numbers etc. Then I had it laminated I still have them

 

[bblawless]

Well there you go. Break out the volt ohm meter and get to testing. Back in late 80's I had my Haynes wiring diagram blown up 24x36 inches - much easier to read big print. On the back I wrote tune up/torque spec's part numbers etc. Then I had it laminated I still have them

I’d love to get my hands on a Haynes manual for this thing, I was just hoping someone could point me in the direction as to where this plug went…I should have taken photos before ripping out the old tub