M151A2 Electrical system not connecting?

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M151A2 Electrical system not connecting?

Post by oldranger63 » Tue Feb 16, 2021 5:40 pm

I have a 1970 M151A2 that hasn't been run since last Oct. 2020. I've kept trickle chargers on both batteries, checked with multi-meter, both batteries are charged. After connecting battery cables, I switched the ignition switch on, but the voltage meter didn't move. Rechecked cables, nothing, replaced ignition switch and still dead. I've searched through the TM's and I'm unable to find a cause for any electrical problem. Has something similar happened or could someone let me know what else to check.

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Re: M151A2 Electrical system not connecting?

Post by hambone » Tue Feb 16, 2021 6:16 pm

I would check for a bad ground, meter grounds through the hold down bracket, also check the ground on the gauge mounting plate, it's grounded to the dash by a ground wire.

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Re: M151A2 Electrical system not connecting?

Post by Rickf » Wed Feb 17, 2021 7:42 pm

Is it just the gauge or do you have no power to anything? Do the headlights work? Does the starter crank the engine? The power comes from the #5 wire which attaches at the starter switch on the floor so if the grounds check out good you might want to check to see if that connection is bad. Be sure to check the ground wire from the batteries to the body, take it off, clean the connection on the body and the wire and put it back. If you are going to check the connections on the starter switch be sure to take the ground cable off the batteries before taking that switch out of the floor. A lot of bare metal exposed there as it comes out, once out you can put some cardboard on the floor and lay the switch on that and hook the batteries back up to test things. Once you are at that point you might as well take the wires and cables off and clean them since you are there. Do that while disconnected.
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Re: M151A2 Electrical system not connecting?

Post by markrdje » Wed Feb 17, 2021 8:17 pm

I would check the gauge 1st to see if it works, which this is a repeat of what rickf said
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