M1009, rear battery dies

[1 Patriot-of-many]

Bought new batteries last winter. The rear battery(closest to firewall) keeps going dead in a week or two. Glow plug system functions properly when battery is recharged. Dash meter shows okay in the green after starting the truck. Front battery stays charged. What should I look for? Or do i just have a bad battery?

 

[jcollings]

Did you confirm each battery With multimeter separately getting Around 14 V When running after starting?

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[WWRD99]

I'd charge up that rear battery with a slow 10 amp charge for several days then get it load tested. After that being it is the 12 volt feed is look for a draw. The somewhat common one is the alternator...can test for that very easy.

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[1 Patriot-of-many]

Did you confirm each battery With multimeter separately getting Around 14 V When running after starting?

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No, Where do i attach the leads right at the battery terminals? Thanks

 

[1 Patriot-of-many]

I'd charge up that rear battery with a slow 10 amp charge for several days then get it load tested. After that being it is the 12 volt feed is look for a draw. The somewhat common one is the alternator...can test for that very easy.

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Okay I will do that, I have a load tester. How do i test the alt for a draw? Thanks

 

[WWRD99]

Okay I will do that, I have a load tester. How do i test the alt for a draw? Thanks

I'd use the 12 volt block up by the glow plug relay...stick the dvom in there and see what volt draw you have. Unplug the alternator.

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[1 Patriot-of-many]

I'd use the 12 volt block up by the glow plug relay...stick the dvom in there and see what volt draw you have. Unplug the alternator.

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dvom?

 

[WWRD99]

dvom?

Digital volt meter

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[1 Patriot-of-many]

Thanks I kinda thought so, but wanted to make sure

 

[jcollings]

No, Where do i attach the leads right at the battery terminals? Thanks

Each battery separate just to confirm both alternators are working properly.
As mentioned, after charging that rear battery, let's sit and then carbon pile test to confirm it's a good battery.
Check your fuse block for melted terminals also problematic on these trucks.

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[1 Patriot-of-many]

Okay guys I've been lax in doing testing after charging the rear battery for a long time. I went out this morning and took my dogs out with my bad back and walked around in the acres then came back to try starting up the m1009, I noticed before I got in the GEN2 light was on and the steering wheel was in the locked position to the left.( you know the steering needs a little more left motion to unlock the steering.) It took little time to to get the glow plug light to turn off and started up fine. COULD THIS BE AS SIMPLE AS REPLACING THE IGNITION SWITCH?

 

[WWRD99]

Okay guys I've been lax in doing testing after charging the rear battery for a long time. I went out this morning and took my dogs out with my bad back and walked around in the acres then came back to try starting up the m1009, I noticed before I got in the GEN2 light was on and the steering wheel was in the locked position to the left.( you know the steering needs a little more left motion to unlock the steering.) It took little time to to get the glow plug light to turn off and started up fine. COULD THIS BE AS SIMPLE AS REPLACING THE IGNITION SWITCH?

Unplug gen 2 and see if that stops. Probably a bad regulator in it.

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[1 Patriot-of-many]

Unplug gen 2 and see if that stops. Probably a bad regulator in it.

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Which one is generator two? Right or left? And does it simply unplug, or do I need to unbolt a cable to the back? Thanks! We're gonna figure this out!

 

[WWRD99]

Which one is generator two? Right or left? And does it simply unplug, or do I need to unbolt a cable to the back? Thanks! We're gonna figure this out!

Passenger side. It's the plug on top of the alternator...2 wire.

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[1 Patriot-of-many]

Thanks again Sir!

 

[1 Patriot-of-many]

Okay guys here's an update, i hate it myself when people don't update their repairs or diagnoses, A few days after I posted last, I went out at night and noticed the gen two was out was out. So i started it expecting to have a dead battery but it energized the glow plugs and started fine. It's been about a week or more and I just went out while dark and the gen2 light is on again! Do I just replace the passenger side alternator at this point? Seems to be the issue.

 

[M813rc]

I had a similar problem with a very small draw in my M1028A2, it took about two weeks, but it would kill my rear battery.
A friend, who is a professional and a whiz at CUCV electrics, spent a long time trying to track it down, checked everything we could think of and all tested good.
I finally just put a keyed battery cutoff switch in. Couldn't hurt to have a little extra thief-slow-down anyway.

Probably not your issue, but one thing to check on CUCVs is the block where the wiring comes into the fuse block through the firewall. There is one bolt in the middle that holds it together, and they seem to loosen up over time, causing all sorts of weird issues, so make sure that is tight.

Cheers

 

[1 Patriot-of-many]

Passenger side. It's the plug on top of the alternator...2 wire.

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Okay So if I pull out the plug and the gen 2 light goes out, it's something in that alternator? I just did a simple volt test after starting the engine and I get about 13.8V at both batteries when running. I'll pull the plug later tonight and post what I get.

 

[1 Patriot-of-many]

Okay Further update, started the truck this afternoon, voltage was 13.8 to both batteries. Shut it down. Gen2 light wasn't on. This evening went out to check on the truck, the gen2 light was back on sitting there. I unplugged the two wire plug to the alternator 2, light went out. So according to the troubleshooting the rectifier bridge needs to be replaced. Is it worth while to remove the alternator and take it apart and replace the rectifier bridge or should I just buy a new alternator WWRD99 ? They seem cheap enough to just replace it.

 

[WWRD99]

Okay Further update, started the truck this afternoon, voltage was 13.8 to both batteries. Shut it down. Gen2 light wasn't on. This evening went out to check on the truck, the gen2 light was back on sitting there. I unplugged the two wire plug to the alternator 2, light went out. So according to the troubleshooting the rectifier bridge needs to be replaced. Is it worth while to remove the alternator and take it apart and replace the rectifier bridge or should I just buy a new alternator WWRD99 ? They seem cheap enough to just replace it.

I rebuild all mine. Not expensive and easy to do. Things I look for is the lower bolt bushing is loose and greased...the front housing sometimes is hard to get out of the bearing.

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