M923 battery switch question


New member
Madison, Alabama
When I turn the battery switch on, the electrical dash gauges don't respond (ie, fuel level doesn't register), and there is no response from turning the starter switch. This had happened intermittently for a while, where after turning the battery switch a few times or letting a little time pass, it would come on. I drove it last week, so it hasn't been sitting for long.

I took the battery switch out and tested voltage to the switch. Circuit 569 from the battery shows over 24v. I tapped on the PCB with a hammer and that didn't have any effect on dash gauges or power to starter switch.

When I do a continuity check on the pins on the back of the battery switch, I get continuity between two of the pins and between the other two pins (I don't know if it's pin A to pin B and pin D to pin C that show continuity or if it's pin A-D and B-C. Didn't have my glasses and couldn't read the tiny pin ABCD labels). Is that normal for this switch, or when it's in the on position should all 4 pins show continuity? In other words, when the switch is on, does it connect circuit 569 from battery to 459 and 81A that go to the PCB and to 569A which goes to the heater, such that my electrical meter would show continuity between all four pins?

The wire from the battery switch labeled 569A was plugged in to the battery switch but ended in a broken and frayed wire. I disconnected wire 569A from the battery switch. From the wiring diagram, this powers the heater and that wire being broken doesn't have anything to do with my problem.

I've ordered a new battery switch since it's a relatively inexpensive part. Is there a way to test the PCB to see if it's the problem?

Secondly, can I bypass the battery switch and PCB and start it by jumping it at the starter? I have a tractor stuck in mud and would like to use the 923 winch to get it out without waiting on parts to arrive.


Former SSG
Steel Soldiers Supporter
AZ/KS/MO/OK, varies by the day...
It's almost certainly the PCB going bad. It can be bypassed.

Or flip the switch back and forth in rapid succession and it'll likely come on.

Simp was selling rebuilt PCBs.


Feo, Fuerte y Formal
Supporting Vendor
Memphis, TN
Is this an NHC250 truck or an 8.3L?

An NHC250 you can screw the front knob on the front of the fuel solenoid in and jump the starter. OR you can take a large 8gauge wire and jump the 2 large pins on the PCB connector plug. THis will send power to your dash and fuel solenoid.

On a 8.3L truck , just zip tie the fuel shut off solenoid up, or use a 10mm socket and remove both bolts and the solenoid completely and jump the starter.

. More than likely it is the PCB with no power to the dash. One way you will know if jumping those large pins if you have power to the dash then you know the solenoids are not energizing.

I have rebuilt and resealed control boxes if you are interested. PM me
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