1985 M923AI AM General electrical problem

[brookfield]

When I attempt to start the truck, I switch the battery disconnect switch to on and turn the ignition key to start.
When I switch the ignition key ON, I hear a click, and the gauges all turn on. THE PROBLEM is sometimes I hear the click, I assume of the relay, BUT, no gauges and truck won't start. If I switch the battery disconnect switch on and off a few times, seams like I find the sweet spot, the dash gauges all turn on and I can start the truck. I thought the battery disconnect switch was bad, I just replaced it today, Didn't help. I still get the same results. When I started having this issue, I installed a 24volt battery tender because my batteries kept going dead. Any ideas?

 

[simp5782]

You should hear 2 series of clicks with the top switch up and the bottom switch up BEFORE you start it. That is your ABS relays cycling. Those are normal.

My gauges do not come to life until i flip the bottom switch ( starter switch) up. I think mine is still wired up as stock but that is how my gauges power up. So you probably have a bad starter switch

 

[brookfield]

If I switch the keyed, bottom, starter switch, nothing happens. The only way I can get anything to work is by turning the, top, battery disconnect switch, on and off until all the dash lights, gauges, and parking brake lights come on, then it will start??

 

[porkysplace]

Might be some help in this thread.;
Starting issues on a m923a1, looking for additional thoughts/suggestions
[h=1]5 ton just clicks??[/h]
More info on the PCB here;
https://www.steelsoldiers.com/showthread.php?113634-Ever-see-inside-the-Protective-Control-Box/page3

 

[simp5782]

If I switch the keyed, bottom, starter switch, nothing happens. The only way I can get anything to work is by turning the, top, battery disconnect switch, on and off until all the dash lights, gauges, and parking brake lights come on, then it will start??

probably a bad PCB. Turn the top switch up and the bottom switch up. Then smack the PCB under the hood with a hammer and see if your truck will start then. Your lights should be allowed to come on all the time regardless of switch position.

 

[brookfield]

Thanks. I'll try that. Looks like everything I'm finding points to the PCB.
I just did a internet search but did not find one?
This is the only truck I have to haul Maple Sap, It's syrup season and I really need to get it going again.

 

[simp5782]

Thanks. I'll try that. Looks like everything I'm finding points to the PCB.
I just did a internet search but did not find one?
This is the only truck I have to haul Maple Sap, It's syrup season and I really need to get it going again.

PM Member FuzzyToaster. He has good tested take off units for sale.