Odd starting issue

[engineman2]

I searched the forum and could not find an issue quite like this. I warn you this will be a long post. For starters the truck is a 1984 M1008 with the Roscommon 12v conversion. It also has a fusible intermittent push button switch as indicated in the photos. The pushbutton must be pushed in addition to the key being turned to the ‘start’ position because it is between the starter relay and the starter solenoid.

I really don’t quite understand why the pushbutton is there because it was installed two owners ago. I never paid it any mind until it started to blow the fuses yesterday. I have gone through three 15 amp fuses so far, as it only blows them sometimes. I can’t get the truck to blow them consistently, so I can’t really narrow down the issue. When the truck starts it does fine and fires right up. When it doesn’t I find another burnt fuse. Replacing the fuse fixes it until the next time it blows. I have checked for any shorts in the purple wire and switch wiring and can’t find any. I may possibly have a shorting pushbutton switch, I have yet to try that.

I have included pictures of the wiring as well as the TM diagram with the wire and switch location highlighted. The wiring diagram pic is self explanatory. The 'behind dash' pic is behind the dash and just under and to the left of the steering column. The third 'under hood' pic is the backside of the fuse box showing where the switch is spliced in. I’m wondering if the Doghead mod would fix this problem and potentially eliminate the need for the pushbutton. Thanks, Emery.

 

[Tlauden]

Wow, look at all that hacked wiring, and that home brewed inline fuse holder...

If I were you I would return the wiring to stock, get rid of that rats nest of wire and electrical tape. If you really want to keep the push button I would start by "cleaning up" that rats nest. Remove all that tape, re-do the connections, get a legit in line fuse, and heat shrink all the connections when you are done. That may solve your issue, If it doesnt then you can keep trouble shooting elsewhere.


I'm speaking from general electrical experience, I don't have much knowledge of cucv's. Normally cleaning up a "hacked" wiring job will help fix the problem. Good luck

 

[M1008driver]

nevermind...I would try a new switch first, then figure out how to fix what was done after you get going. Probably a new in-line fuse too like was mentioned.

 

[engineman2]

Yes Tlauden, I know the wiring is quite a hackjob, but it has clean connections and should work, although it doesn't look too good. I've been planning to clean it up but haven't. M1008driver Are you referring to the key switch or the pushbutton? I just replaced the pushbutton , so we'll see if that fixes it since it shorts randomly.

 

[M1008driver]

Push button. Fix the easiest most obvious first if in doubt.

Some vehicles you turn the key and push a button to start. Maybe this is what the original owner was trying to do. Who knows...

 

[engineman2]

Yeah I replaced the pushbutton. If you look at the wiring diagram though, I just can't see the point in the pushbutton. Unless the owner wanted to make it confusing for car thiefs.