Wiring Question

[Zeus51]

It seems I never have to post anything unless it’s a wiring question. I have had a m1008 for 10 years with no real issues. I have recently acquired a m1009. The previous owner says he converted to 12v but it looks like all he did was disconnect the gen 2 wiring and remove the alt. I have reinstalled a known running gen 2 from a donor m1009 I also have. I traced the wiring to make sure it was solid. I also replaced the gen 1 with a known working gen 1 alternator from my donor. When I disconnect the white clips with the red and brown wires off the alternators, both gen 1 and 2 pass the key on/off test. And both alt’s have the appropriate 12/24v to the post. And the batteries are fully charged reading 12.4v. I have done the Doghead relay and glow plug switch. Since completing all this, the truck would crank and run but the gen 1 light wouldn’t go off and the gen 1 alternator wasn’t charging the front battery. Gen 2 seemed to be working and rear battery was reading 14.6v while running.

Today, I cleaned some terminals and tried to crank it. It wouldn’t crank and the engine grounding strap on the back passenger side of the engine got super hot and started smoking. So I immediately turned it off. before I start purchasing a new grounding strap and troubleshooting blindly, I thought I’d ask opinions on what I should do?

 

[porkysplace]

It seems I never have to post anything unless it’s a wiring question. I have had a m1008 for 10 years with no real issues. I have recently acquired a m1009. The previous owner says he converted to 12v but it looks like all he did was disconnect the gen 2 wiring and remove the alt. I have reinstalled a known running gen 2 from a donor m1009 I also have. I traced the wiring to make sure it was solid. I also replaced the gen 1 with a known working gen 1 alternator from my donor. When I disconnect the white clips with the red and brown wires off the alternators, both gen 1 and 2 pass the key on/off test. And both alt’s have the appropriate 12/24v to the post. And the batteries are fully charged reading 12.4v. I have done the Doghead relay and glow plug switch. Since completing all this, the truck would crank and run but the gen 1 light wouldn’t go off and the gen 1 alternator wasn’t charging the front battery. Gen 2 seemed to be working and rear battery was reading 14.6v while running.

Today, I cleaned some terminals and tried to crank it. It wouldn’t crank and the engine grounding strap on the back passenger side of the engine got super hot and started smoking. So I immediately turned it off. before I start purchasing a new grounding strap and troubleshooting blindly, I thought I’d ask opinions on what I should do?

Did you put a 24v starter on it or are feeding 24v into a 12v starter ?

 

[87cr250r]

In addition to the braided grounding strap that connects between the engine and body, there should also be a battery cable between the 24 volt terminal strip and the engine block as well. This battery cable is necessary to carry the starter current.

 

[Zeus51]

Did you put a 24v starter on it or are feeding 24v into a 12v starter ?

I asked the guy if he swapped the starter to 12v when he did conversion. His answer was no which confuses me a little bc he had it connected to a 12 volt terminal. I did check that terminal before dismantling what he had done. Maybe the starter was getting just enough juice to turn over?

 

[Zeus51]

In addition to the braided grounding strap that connects between the engine and body, there should also be a battery cable between the 24 volt terminal strip and the engine block as well. This battery cable is necessary to carry the starter current.

you mean: coming off the same terminal that the grounding strap terminates at on the engine? Yes. There is a grounding cable that also connects there and goes to the ground block on the firewall. That same bolt also has a small black wire connected there that I think is a splice from the diagnostics? Does that sound correct?

 

[nyoffroad]

I asked the guy if he swapped the starter to 12v when he did conversion. His answer was no which confuses me a little bc he had it connected to a 12 volt terminal. I did check that terminal before dismantling what he had done. Maybe the starter was getting just enough juice to turn over?

Based on what little experience I've had seeing 24 volt starters getting just 12 volts is that they don't work at all! This might be an anomaly but in both cases the solenoid would kick the starter gear out and then try to turn the engine but couldn't, leaving the starter drive engaged and acting like the engine was seized. With that in mind I think you have a 12 volt starter.

 

[Zeus51]

Based on what little experience I've had seeing 24 volt starters getting just 12 volts is that they don't work at all! This might be an anomaly but in both cases the solenoid would kick the starter gear out and then try to turn the engine but couldn't, leaving the starter drive engaged and acting like the engine was seized. With that in mind I think you have a 12 volt starter.

hmmm. When you put it that way, now I feel like a dummy for assuming something that in hindsite doesn’t make any sense. Haha! That’s an easy fix. When I get home, I’ll try using 12v and report back.

 

[Mullaney]

hmmm. When you put it that way, now I feel like a dummy for assuming something that in hindsite doesn’t make any sense. Haha! That’s an easy fix. When I get home, I’ll try using 12v and report back.

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Or measure voltage with a meter...

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[Zeus51]

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Or measure voltage with a meter...

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Or measure voltage with a meter...

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Can I measure the expected volt draw without actively turning over the engine?

 

[Mullaney]

Can I measure the expected volt draw without actively turning over the engine?

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You can definitely see if you have 12v or 24v feeding the starter. The bendix gets "kicked out" only when you turn the key

 

[Zeus51]

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You can definitely see if you have 12v or 24v feeding the starter. The bendix gets "kicked out" only when you turn the key

You’re saying the solenoid will read 12v regardless of being connected to 24v?

 

[87cr250r]

The top large lug on the solenoid is connected directly to battery + and is always live. You can measure the voltage to the starter there. There should be a nameplate on the starter that says what voltage it is. There should also be voltage numbers stamped into the solenoid but these will be hard to see with the starter installed.

 

[Zeus51]

The top large lug on the solenoid is connected directly to battery + and is always live. You can measure the voltage to the starter there. There should be a nameplate on the starter that says what voltage it is. There should also be voltage numbers stamped into the solenoid but these will be hard to see with the starter installed.

The top large lug on the solenoid is connected directly to battery + and is always live. You can measure the voltage to the starter there. There should be a nameplate on the starter that says what voltage it is. There should also be voltage numbers stamped into the solenoid but these will be hard to see with the starter installed.

the large lug measures 24v. I took pics to judge the starter but I didn’t see the text you refer to

 

[porkysplace]

the large lug measures 24v. I took pics to judge the starter but I didn’t see the text you refer to

Do you have other stock CUCV's ? ...... swap a starter off one of them or pull that starter and search the numbers on it to find out if it is 12 v or 24 v. This is why most people run far and fast from 12v conversions , for the most part your on your own trying to figure out what Bubba did . The Rosscommon conversion at least has a wiring diagram .

 

[adf5565]

I hope you just took the starter brace off to take the pictures and it hasn’t been running that way for a while!

 

[Zeus51]

Do you have other stock CUCV's ? ...... swap a starter off one of them or pull that starter and search the numbers on it to find out if it is 12 v or 24 v. This is why most people run far and fast from 12v conversions , for the most part your on your own trying to figure out what Bubba did . The Rosscommon conversion at least has a wiring diagram .

Yeah, I’ve got a donor that’s definitely a 24v starter. I’ll probably just swap them. Especially after looking at the pics and noticing the purple exciter wire terminal is busted on the solenoid. BUT!!!

I did just say the hell with it and swapped the starter wire to a 12v terminal on a battery since the previous guy had it 12v. It cranked right up. The braided ground strap still had slight smoking for 1-2 secs then stopped. And was cool to touch in 5 mins of running it. And somehow, both batteries were charging this time.

I don’t think I’m over this issue yet. I just think the electrical gremlins weren’t pissed off before this crank.

 

[Zeus51]

I hope you just took the starter brace off to take the pictures and it hasn’t been running that way for a while!

I know right? I got this thing and immediately dove into the issues. I only drove it down my driveway. So I’ve only cranked it once before popping the hood and starting to work

 

[adf5565]

I know right? I got this thing and immediately dove into the issues. I only drove it down my driveway. So I’ve only cranked it once before popping the hood and starting to work

Hopefully nothing else too major after you work through this issue.

 

[nyoffroad]

The top large lug on the solenoid is connected directly to battery + and is always live. You can measure the voltage to the starter there. There should be a nameplate on the starter that says what voltage it is. There should also be voltage numbers stamped into the solenoid but these will be hard to see with the starter installed.

"there should be a nameplate" Really? I've never seen one before, just the 24V stamped on the solenoid. I always thought there should be a better way!

 

[Zeus51]

Going back to the engine grounding terminal on the back of the passenger side head with the firewall grounding strap attached to.

There is a grounding cable that goes to the grounding block on the firewall. But there is also a mystery black wire coming out of the wiring harness and terminating on the engines ground terminal along with the other two.

I can’t find it on the wiring diagrams. What does that black wire go to?