F Model dash fire

[JeffD11N]

Guys I'm new to this forum and was sent here by Barry at Watt's. Can anyone please help me with a dash fire on our 1982 F Model.

I was driving along and it just quit and the cab filled with smoke. Everything seems to work other than the shut down solenoid. If you hotwire the solnoid it will pull the rod in and start and run. Thats how we got it home.

My problem is I do not know where anything is located from the key switch to the solehnoid. When I look behind the dash I can not find anything that is obviously burnt. I'm afraid it's inside the wiring loom.

Can anyone tell me wich wire from the key switch is the one I need to trace and maybe where the relays or circuit breakers are located for this circuit?

Everything is so tight and stiff from age I know I am in for a big job. I need help!

Thanks,

Jeff

[TeamsterGrrrl]

If you haven't already done so, disconnect the batteries! Don't want to have another short burn up the rest of the truck while you're finding the first short.

[mrsmackpaul]

welcome Jeff

if you lost everything it sounds like you lost power from the alternator battery side before it gets to the switch so maybe you dont have to dive in as much as you think

The live wire or hot wire would come from the battery to the key switch first at least thats were most of the circuits would it's a bit hard to tell with out a wiring diagram but it dosnt sound real bad to me as in most of it sounds un burnt

You need to find a wiring diagram some one on here Im sure will put one up fairly soon we should be able to locate which wire is crook with out pulling to much apart once you get a diagram

Paul

[j hancock]

Here is a link to a 1983 wiring diagram. Even though it is for an R model the vast majority of electrical components are the same or similar to an F model. It is for a negative ground vehicle.

http://www.bigmacktrucks.com/index.php?/tutorials/article/55-r-model-wiring-diagram/

[JeffD11N]

Batteries are not a problem as I put a Master switch in this years ago for just this reason.

I did not loose everything just the shutdown. I disconnected it and ran a fused hotwire from a battery to the fuel pump to get it home. Everything else seems just fine and everything works. Seems to me that whatever burnt, burnt out completely as there has been no problems with it while nursing it home. I'm afarid it is inside the wiring loom where you can not see it. That is why I think I have a real big job on my hands as you can not reach80% of the harness without tearing the dash out completely as I see it.

Thanks for the wiring diagram. The colors on the key switch are not the same at all. If I just knew the exact color of the wire I could cut open the loom every so often and spot check the wire for continuity to narrow down the search.

I do not see a shutdown relay that is like the one I have in the diagram though. This is a 285/300 with an American Bosch pump. The relay has only the hot wire from the cab and another one that goes directly to ground. I have nothing that resembles the Kysor shut down that I can see. Heck someone needs to explain the Kysor shutdown to me anyway.

[Superdog]

put a cable kill switch on it like should be,do away with the electric one,problem solved.

[Underdog]

put a cable kill switch on it like should be,do away with the electric one,problem solved.

A buddy of mine was so proud to show me he put a cable shut off on his A model CAT in a KW... now he has it " just like a Mack"

Sent from my XT1254 using Tapatalk

[PANELIZER]

Jeff,

Attached is a wiring diagram for an F model with a negative ground, If you truck has positive ground I have that one also. It it from a Mack electrical manual dated 1985. Hope this helps.

MACK F NEGATIVE GROUND.pdf

[JeffD11N]

Panelizer,

This one has really helped me for some ideas. I remember changing the accessory relay behind the heater controlls some years ago. Seems to me that there were two of those big tall round relays in there. I'm thinking the other one might be the engine brake relay that is connected to the injection pump solinoid in this diagram.

These are in a complete different place than where the smoke came pouring out of the dash but that really doesn't mean much. I think I have a place to start on each end now.