M817 electrical

[1Ranchhand36]

I'm working on a M817. Have no power to the truck. Cleaned and reworked all the battery cables, good battery power. Nothing when I turn on the battery switch in cab. Does that sound like a control box? Still tracing wires but nothing so far. Could use y'all's help, thanks.

 

[Scar59]

Yes, sounds like the PCB. Pull the connector off the box and put a meter on it. Should have 24 v on one of the large pins. There is a post regarding trouble shooting the PCB. Lots of good info and instructions to make a jumper lead to jump the connector and get it started.

 

[Csm Davis]

Turn on the power and then wack the black box hard, many times that will make them start working.

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[1Ranchhand36]

Thanks, I'll try these suggestions and see what happens. Thanks for your help.

 

[1Ranchhand36]

Got it going!!!!! Finally, I can put this thing to work. Thanks for your help. I read the posts about the PCB and learned a good deal about it, thanks. Then out of desperation I got a hammer and whacked it, that's all it took. Cranked right up and is running great. It's awesome when hitting it with a hammer really works, thanks.

 

[Scar59]

That is called a "percussion adjustment". The PCB might just need some use, exercise the relays, master switch, on -off -on -off several times. Then again the PCB might be getting ready to fail forever. The percussion adjustment may not work the next time. The relays in the PCB can be replaced with a little time and patience.

 

[Floridianson]

That is called a "percussion adjustment". The PCB might just need some use, exercise the relays, master switch, on -off -on -off several times. Then again the PCB might be getting ready to fail forever. The percussion adjustment may not work the next time. The relays in the PCB can be replaced with a little time and patience.

I would agree on the ( Then again getting ready to fail forever part.) I would look into replacement or correct repair if the PCB.

 

[Csm Davis]

Got it going!!!!! Finally, I can put this thing to work. Thanks for your help. I read the posts about the PCB and learned a good deal about it, thanks. Then out of desperation I got a hammer and whacked it, that's all it took. Cranked right up and is running great. It's awesome when hitting it with a hammer really works, thanks.

Glad you got it going. Now listen to me and the other two guys, go buy another box.

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[1Ranchhand36]

Ordered a new box today, thanks for y'all's help and have a great weekend.