Battery Connections??? Glow Plug cycle???

Dispatcher7

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Location
Pittstown, NY
Someplace on this site I had found the electrical schematics for the M1009, I can not find them again. If you have a link to them to share I would appreciate it.

The truck starts and runs fine. Well it starts when it's warm. While checking the glow plugs I discovered the batteries are connected in series. The + terminal on the front battery is connected to the - terminal on the rear battery. The - on the front battery goes to the - bus bar on the fire wall. The - on the rear battery then has a smaller cable going to a solenoid looking device on the firewall just left of the master cylinder and the + of the rear battery goes to the 24v bus bar. I do not believe this is the way it should be, is it?

I can also tell you that the volt gauge on the right side of the instrument panel does not work. And neither GEN light comes on when the key is turned on. Ive been reading a lot of post on here and if I understand things correctly if the GEN light does not come on it could be the alternator, the wire harness or the bulb. But before I dive too far into this Im curious about the above battery questions and if maybe someone did a half ass 12v conversion.

Now back to the glow plugs. I do have voltage to the plugs. Unfortunately my multi meter is not working so I don't know how many volts and could not measure the resistance on the GP's. I'll get a new meter later this week to finish those test. I did see that the GP's have a sort wire coming from the GP to the factor GP wire and the GP terminal is wider than the OE plug. I assume someone installed non military GP's and did this to overcome the different terminal width. I have also noticed the WAIT TO START light does stay on a lot longer when its colder out and does not cycle on/off/on. I've read so much on here my mind is boggled. Do the military trucks cycle on/off/on or was that just the civilian systems? Somewhere I read that if they do not cycle and are supposed to it indicates a problem with the control board. But I believe the longer WAIT when colder is correct.

Oh and one other question. Smack dab in the center of the firewall right behind the air cleaner is a large metal bracket with something mounted behind it. I can see where some large wires possibly battery cables have been cut off from whatever is behind this bracket. Before I go and take this off to see what is behind there can anyone tell me what to expect?

Thanks for anything you can offer.
 

Dispatcher7

New member
24
20
3
Location
Pittstown, NY
Someplace on this site I had found the electrical schematics for the M1009, I can not find them again. If you have a link to them to share I would appreciate it.

The truck starts and runs fine. Well it starts when it's warm. While checking the glow plugs I discovered the batteries are connected in series. The + terminal on the front battery is connected to the - terminal on the rear battery. The - on the front battery goes to the - bus bar on the fire wall. The - on the rear battery then has a smaller cable going to a solenoid looking device on the firewall just left of the master cylinder and the + of the rear battery goes to the 24v bus bar. I do not believe this is the way it should be, is it?

I can also tell you that the volt gauge on the right side of the instrument panel does not work. And neither GEN light comes on when the key is turned on. Ive been reading a lot of post on here and if I understand things correctly if the GEN light does not come on it could be the alternator, the wire harness or the bulb. But before I dive too far into this Im curious about the above battery questions and if maybe someone did a half ass 12v conversion.

Now back to the glow plugs. I do have voltage to the plugs. Unfortunately my multi meter is not working so I don't know how many volts and could not measure the resistance on the GP's. I'll get a new meter later this week to finish those test. I did see that the GP's have a sort wire coming from the GP to the factor GP wire and the GP terminal is wider than the OE plug. I assume someone installed non military GP's and did this to overcome the different terminal width. I have also noticed the WAIT TO START light does stay on a lot longer when its colder out and does not cycle on/off/on. I've read so much on here my mind is boggled. Do the military trucks cycle on/off/on or was that just the civilian systems? Somewhere I read that if they do not cycle and are supposed to it indicates a problem with the control board. But I believe the longer WAIT when colder is correct.

Oh and one other question. Smack dab in the center of the firewall right behind the air cleaner is a large metal bracket with something mounted behind it. I can see where some large wires possibly battery cables have been cut off from whatever is behind this bracket. Before I go and take this off to see what is behind there can anyone tell me what to expect?

Thanks for anything you can offer.
OK, I did some more on-line research and found that the batteries are wired correctly. I also learned that part behind the air cleaner is the GP resistors, but appears to have been disconnected. So now I'm curious why this was disconnected? What else should I look for in the GP system?

Thanks again.
 

MarcusOReallyus

Well-known member
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Location
Virginia
OK, I did some more on-line research and found that the batteries are wired correctly. I also learned that part behind the air cleaner is the GP resistors, but appears to have been disconnected. So now I'm curious why this was disconnected?

That's a very common modification. If you look in the Helpful Threads" sticky (top of the forum), you'll see there are a couple of threads on the resistor bypass. Those will explain the why and how.
 

Dispatcher7

New member
24
20
3
Location
Pittstown, NY
What is feeding voltage to your GP solenoid?

Pictures help everyone here help you. Post a few if you can.
Good question. If I see it right the red wire from the rear battery - terminal goes to a junction block and that has a red wire to what I believe to be the GP solenoid. Maybe this picture will help?M1009 GP Wires.jpg
 

Curtisje

Well-known member
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Location
Twentynine Palms, CA
Good question. If I see it right the red wire from the rear battery - terminal goes to a junction block and that has a red wire to what I believe to be the GP solenoid. Maybe this picture will help?View attachment 827184
Yup. It's getting 12v from the front battery which is fine. The resistors on the firewall were fed 24v from the 24v bussbar. When the GP system engaged it dropped the 24v to 12v. As Marcus stated simply feeding 12v to the GP solenoid is a common modification.

You should check the state of your batteries. These trucks don't act well if your batteries aren't in tip top shape. They should each have 12.6 volts with everything off.
 

dougco1

Active member
657
179
43
Location
Cooperstown NY
Someplace on this site I had found the electrical schematics for the M1009, I can not find them again. If you have a link to them to share I would appreciate it.

The truck starts and runs fine. Well it starts when it's warm. While checking the glow plugs I discovered the batteries are connected in series. The + terminal on the front battery is connected to the - terminal on the rear battery. The - on the front battery goes to the - bus bar on the fire wall. The - on the rear battery then has a smaller cable going to a solenoid looking device on the firewall just left of the master cylinder and the + of the rear battery goes to the 24v bus bar. I do not believe this is the way it should be, is it?

I can also tell you that the volt gauge on the right side of the instrument panel does not work. And neither GEN light comes on when the key is turned on. Ive been reading a lot of post on here and if I understand things correctly if the GEN light does not come on it could be the alternator, the wire harness or the bulb. But before I dive too far into this Im curious about the above battery questions and if maybe someone did a half ass 12v conversion.

Now back to the glow plugs. I do have voltage to the plugs. Unfortunately my multi meter is not working so I don't know how many volts and could not measure the resistance on the GP's. I'll get a new meter later this week to finish those test. I did see that the GP's have a sort wire coming from the GP to the factor GP wire and the GP terminal is wider than the OE plug. I assume someone installed non military GP's and did this to overcome the different terminal width. I have also noticed the WAIT TO START light does stay on a lot longer when its colder out and does not cycle on/off/on. I've read so much on here my mind is boggled. Do the military trucks cycle on/off/on or was that just the civilian systems? Somewhere I read that if they do not cycle and are supposed to it indicates a problem with the control board. But I believe the longer WAIT when colder is correct.

Oh and one other question. Smack dab in the center of the firewall right behind the air cleaner is a large metal bracket with something mounted behind it. I can see where some large wires possibly battery cables have been cut off from whatever is behind this bracket. Before I go and take this off to see what is behind there can anyone tell me what to expect?

Thanks for anything you can offer.
It sounds as if your truck has had several modifications. Unfortunately, "unless the PO has left you a modification log" you will have to figure them out for yourself.
That's why I'm a firm believer of oem parts and repairs and not "re-designing" these trucks.

Now you will have to trace each issue one at a time

Glow plugs - There are many things that can cause hard cold starts and short glow plug cycles but first check that all your glow plugs are good. The wait light should stay on relatively longer when the truck is colder. If not, your glow plug temp censor could be bad, a bad glow plug controller card, or one or more of your glow plugs may be burnt out. Start with checking the glow plugs. You say your multi meter is shot. If you have a simple test light you can test continuity of your plugs by simply connecting the alligator clip to your battery positive and touching the spade end of your glow plugs with the probe. If it lights up then the plug is not burned or shorted. Some members actually remove the plugs and bench test them but that in my humble opinion is a lot of unnecessary work.

If the plugs test good I would move on to your GP temp censor located drivers side rear of engine on top behind the air cleaner. On many of the original censors, the plug end has disintegrated and is no longer making good connection. If that's not the case it could be the censor itself. I'm not sure what the testing process is but it would require a "working" multi meter. You somehow would have to test resistance at different temperatures. Or like mine, I new it was bad and just replaced it with a new one.

Trouble shoot/confirm those items first and move on from there. Maybe a bad card?
 

Dispatcher7

New member
24
20
3
Location
Pittstown, NY
It sounds as if your truck has had several modifications. Unfortunately, "unless the PO has left you a modification log" you will have to figure them out for yourself.
That's why I'm a firm believer of oem parts and repairs and not "re-designing" these trucks.

Now you will have to trace each issue one at a time

Glow plugs - There are many things that can cause hard cold starts and short glow plug cycles but first check that all your glow plugs are good. The wait light should stay on relatively longer when the truck is colder. If not, your glow plug temp censor could be bad, a bad glow plug controller card, or one or more of your glow plugs may be burnt out. Start with checking the glow plugs. You say your multi meter is shot. If you have a simple test light you can test continuity of your plugs by simply connecting the alligator clip to your battery positive and touching the spade end of your glow plugs with the probe. If it lights up then the plug is not burned or shorted. Some members actually remove the plugs and bench test them but that in my humble opinion is a lot of unnecessary work.

If the plugs test good I would move on to your GP temp censor located drivers side rear of engine on top behind the air cleaner. On many of the original censors, the plug end has disintegrated and is no longer making good connection. If that's not the case it could be the censor itself. I'm not sure what the testing process is but it would require a "working" multi meter. You somehow would have to test resistance at different temperatures. Or like mine, I new it was bad and just replaced it with a new one.

Trouble shoot/confirm those items first and move on from there. Maybe a bad card?
Hey buddy, I drove past Cooperstown Sunday bringing this truck home from Ohio.

After doing much more searching and reading it is looking like the GP resistor modification may be all I'm dealing with. Praying that is so anyway. No modification log from the prior owner.

I never thought of the continuity test for the GP's I was heading down the resistance test route. I will try this when I get home tonight. Since the WAIT light does act differently with temperature I am in hopes the sensor and controller are all good. The engine will spin real nice and quick, and it chugs like its trying to fire on one or two cylinders. I am really thinking I will find several bad GP's. If the engine is warm it fires right up immediately.

I'm now wondering did they do this modification because the resistors were bad or because they wanted to put in different GP's. Is there a test for the resistor? If my problem turns out to be several bad GP's would it make sense to go back to OE? With all of the reading I have done on here I have to agree, fix what's broken don't redesign it. Unfortunately the prior owner had a different idea.

Thanks for the help!
 

dougco1

Active member
657
179
43
Location
Cooperstown NY
Try not to waist time second guessing why the PO did the resistor by-pass. The resistor rarely goes bad but??? maybe he was replacing a lot of GPs and thought that would solve the problem. My glow plugs in my M1009 have being going strong for more than 10 years now. But I don't start it or drive it in the winter like the history your ride with a plow suggest. Starting these Beast in the cold winter is tough on them. It should work just fine with the resistor by-passed as long as all your plugs are good. But keep in mind you are transferring all the electrical load onto one battery. If you keep cranking and its not starting quickly, your drawing that battery down much quicker and you can burn out/weld your starter relay under the dash and burn up your wiring.

Keep your batteries up to par by trickle charging them while troubleshooting your cold start issues[/QUOTE]
 
Last edited:

Dispatcher7

New member
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20
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Location
Pittstown, NY
Just thought I would give an update.

I replaced all 8 GP's with AC60G's. 12 degrees out and it starts right up! Now a prior owner had made short connectors to compensate for the difference in connector width and did a horrible job at it. Non-insulated connectors, lots of corrosion. Once we get some warmer weather I will be replacing the wire fro the GP's to the Relay.

Thanks for all of the help.
 

cucvrus

Well-known member
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2,606
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Location
Jonestown Pennsylvania
You could also eliminate the connection adapters completely get a set of resistors and put AC Delco 13 G glow plugs in it. I have used the stock set up thru hundreds of thousands of miles and have seldom been left down. Glow plug and starting issues never left me stranded at the side of the road. I have found it so much easier to correct and diagnose the stock system. And after 26 years of private ownership I still maintain stock systems only. Good Luck. Be Safe.
 
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