M1008 Won't Start

rmesgt

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Hello All.... My M1008 has suddenly determined that it no longer wants to be my daily driver, refusing to start. I recently replaced both batteries so my starter seems to crank quickly. Today, I noticed that the GP solenoid clicks on/off rather quickly. I am used to turning the key, hearing the GP solenoid click "on", then after about 15 seconds, the "wait" light goes out and the GP solenoid clicks "off". Now when I turn the key to the "On" position, I hear the GP solenoid click "on", and then about two to three seconds later, it clicks "off". It does this repeatedly. When the GP solenoid clicks "on" then "off" the first time, the wait light goes out and doesn't come back on even as the GP solenoid continues to oscillate. After several oscillations of the "on/off" solenoid action, I try to start my truck but to no avail.

WHAT I HAVE DONE:

a. I swapped the GP controller circuit cards between my M1008 and M1009. Same problem occurs.
b. I swapped the GP Solenoids between the M1008 and the M1009. Same problem occurs.


WHAT I HAVE NOT DONE:

a. I have not yet removed and checked the glow plugs on the M1008
b. I have not tested the voltage (0hms?????) at the glow plugs as the GP Solenoid oscillates.
c. I have not tried to bypass the GP resistors behind the Air Cleaner.

Question 1: Would failed glow plugs cause the GP Solenoid to short cycle "on/off, on/off, etc?
Question 2: Could the new batteries have caused this problem?
Question 3: How do check the wiring at the glow plugs to determine how much voltage (Ohms????) I have at the plugs?
Question 4: How much voltage or ohms should I be getting at the glow plug as the GP solenoid oscillates?
Question 5: Has anyone else experienced this problem?

I have been pouring over the historical threads on this subject, but I have not found my starting problem in a previous discussion. No doubt it is there, but I haven't had any luck in discovering the thread. I did see where there are three possible "camps" into which a person might fit. Personally, I think I am in the "Lets make it better" camp, which is why I installed the Doghead Starter Relay Modification to both of my trucks. If removing the resistors and running a new wire and push button switch is the cure, I am all for it.

Thoughts Anyone?????
 

cucvrus

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Remove and check the glow plugs. The system is protecting itself by cycling on and right off. You have the list in order. Check the glow plugs before anything get bypassed.
 

rmesgt

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Remove and check the glow plugs. The system is protecting itself by cycling on and right off. You have the list in order. Check the glow plugs before anything get bypassed.
Thank you for the reply. I will check my glow plugs shortly. I never thought I would again use the glow plug tester that I built, but it seems that now I have a reason...! (Too Much Time On My Hands - Styx)
 

rmesgt

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CUCVRUS.... You were right on the money! All 8 glow plugs were inop. I remember a while ago that I left the key on overnight, which is what probably fried them. New plugs are ordered and should be here by tomorrow AM.
 

2INSANE

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CUCVRUS.... You were right on the money! All 8 glow plugs were inop. I remember a while ago that I left the key on overnight, which is what probably fried them. New plugs are ordered and should be here by tomorrow AM.
I did this twice! Fried the batteries, fried the glow plugs and fried the glow plug resister on firewall. After replacing the batteries and glow plugs, it took twice as long to heat up the GP because the resisters were fried. Took 1 year to finally realize that the resisters were shot too. I eventually removed them and did the bypass.

I recommend testing the resisters to see if they still work after you replace the glow plugs. The G60’s self regulate at 10.5 volts. Bad resister will drop the GP voltage to 6.5 if bad.
 

rmesgt

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I did this twice! Fried the batteries, fried the glow plugs and fried the glow plug resister on firewall. After replacing the batteries and glow plugs, it took twice as long to heat up the GP because the resisters were fried. Took 1 year to finally realize that the resisters were shot too. I eventually removed them and did the bypass.

I recommend testing the resisters to see if they still work after you replace the glow plugs. The G60’s self regulate at 10.5 volts. Bad resister will drop the GP voltage to 6.5 if bad.
I replaced the batteries as the crew at O'Reilly Auto determined they were bad. I did not order the G-60 Glow Plugs. I ordered the AC Delco 13G plugs as recommended in other posts. They are due in tomorrow.

I would like to test the resistors. I imagine the way to test the resistors is to turn on the key and check the voltage at each glow wire which will be 8 tests providing the Glow Plug Solenoid doesn't oscillate. Perhaps the other way to test the resistors is to check the voltage where the resistor wire connects to the top of the solenoid.

Ideas? Thoughts? Opinions? I have never tried to conduct this test.
 

2INSANE

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I replaced the batteries as the crew at O'Reilly Auto determined they were bad. I did not order the G-60 Glow Plugs. I ordered the AC Delco 13G plugs as recommended in other posts. They are due in tomorrow.

I would like to test the resistors. I imagine the way to test the resistors is to turn on the key and check the voltage at each glow wire which will be 8 tests providing the Glow Plug Solenoid doesn't oscillate. Perhaps the other way to test the resistors is to check the voltage where the resistor wire connects to the top of the solenoid.

Also test your relay. There is a chance the the long heavy load could have welded the relay together inside or burnt the connection inside.

Ideas? Thoughts? Opinions? I have never tried to conduct this test.
I never ran the 13G glow plugs. I am not sure what the voltage is per plug. I would assume around 12.5-11.5 drop.

To my knowledge, the resister basically resists/converts the 24volt to 12 volt. So test each end of the resister. One side should be 24 volt and the other about 12volt. Depends if the motor is on turning the dual alternators.

There are perhaps others that could correct me if I am wrong?
 

rmesgt

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Thank you for the response...! Checking each end of the resistor makes sense. I hadn't considered that path. I will continue to investigate how to check these resistors. I would like to keep my truck stock if possible. If my resistors are toast, I think I get replacement parts from Hillbilly Wizard, Ebay, etc. I will test them tomorrow. I am guessing that they can be tested while the engine is not running as that is how they deliver the energy to the glow plugs. Your thoughts???
 

redlight

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Thank you for the response...! Checking each end of the resistor makes sense. I hadn't considered that path. I will continue to investigate how to check these resistors. I would like to keep my truck stock if possible. If my resistors are toast, I think I get replacement parts from Hillbilly Wizard, Ebay, etc. I will test them tomorrow. I am guessing that they can be tested while the engine is not running as that is how they deliver the energy to the glow plugs. Your thoughts???
Remember that there is a voltage drop only when there is a current flow. if you disconnect one side there will not be a flow and the voltage will be the same on both ends. if you disconnect one end then you can measure resistance (OHMS). I do not know what the resistance should be.
 

cucvrus

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I did this twice! Fried the batteries, fried the glow plugs and fried the glow plug resister on firewall. After replacing the batteries and glow plugs, it took twice as long to heat up the GP because the resisters were fried. Took 1 year to finally realize that the resisters were shot too. I eventually removed them and did the bypass.

I recommend testing the resisters to see if they still work after you replace the glow plugs. The G60’s self regulate at 10.5 volts. Bad resister will drop the GP voltage to 6.5 if bad.
Why not just replace the resistors. Just saying they were put there for a reason. Keep it stock and keep it simple. It worked for 36+ years like it is. Soon an unmolested, unhacked CUCV will be a rarity. Do as you wish. The resistors do work a long time and when they fail replace them. Just like other parts. Nothing is infallible. I have a pile of the resistors complete. Bought everyone I seen because I heard they fail. Over 25 years of CUCV's and hundreds of thousands of miles and never had 1 failure. Thus I have lots of spares. Good Luck. Be Safe.
 

Curtisje

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I never ran the 13G glow plugs. I am not sure what the voltage is per plug. I would assume around 12.5-11.5 drop.

To my knowledge, the resister basically resists/converts the 24volt to 12 volt. So test each end of the resister. One side should be 24 volt and the other about 12volt. Depends if the motor is on turning the dual alternators.

There are perhaps others that could correct me if I am wrong?
Not true. The output side of the resistor with show 24v with a multimeter. It drops the voltage to 12v when the glowplug system draws from the system during startup. The resistors are part of the system, they don't work independently of the system.
 

2INSANE

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Why not just replace the resistors. Just saying they were put there for a reason. Keep it stock and keep it simple. It worked for 36+ years like it is. Soon an unmolested, unhacked CUCV will be a rarity. Do as you wish. The resistors do work a long time and when they fail replace them. Just like other parts. Nothing is infallible. I have a pile of the resistors complete. Bought everyone I seen because I heard they fail. Over 25 years of CUCV's and hundreds of thousands of miles and never had 1 failure. Thus I have lots of spares. Good Luck. Be Safe.
Many years ago when my resisters fried, I went searching for a new set. I could not find any. At that time, they did not make them anymore. I did not want to take any chances with buying a used set. Hence the bypass.

I agree keeping it all stock is more beneficial.


Not true. The output side of the resistor with show 24v with a multimeter. It drops the voltage to 12v when the glowplug system draws from the system during startup. The resistors are part of the system, they don't work independently of the system.
You just explained what I already explained, but in more of a technical way;-) I did not say consistently. Yes we are both correct.

“To my knowledge, the resister basically resists/converts the 24volt to 12 volt.“

“It drops the voltage to 12v when the glowplug system draws from the system during startup.”
 

cucvrus

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The resistors also assist over voltage during jump start. I am NOT 100% knowledgeable but I have just followed the original blue prints since 1984 and have had rave results. Eliminates the guess work and speculation. All is Well. Take Care.
 

dependable

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The resistor is only needed when jump starting w slave cable when the batteries in jumped vehicle are almost completely dead. Jumping works fine without the resistor otherwise. I send crew out in these trucks daily, carry a slave cable in my personal truck at all times.

The reason people disconnect it is because if resistor fails, glow plugs will fry, more importantly and more common; if one glow plug fails, the voltage to the others will go above 12V and can cause cascading glow plug failure. This does not happen if 12V is fed directly to the glow plug relay.

If you want to keep it original, and make glow plug failure less likely, just disconnect resistor wire from 24V bus and glow relay, and connect glow plug relay to 12V at battery or at junction on firewall above relay. Leave the resistor and its wires in place and hook them up in a minute if you want to go through resistor.

Remenber, if you need to start truck and the glow plugs are good, but something else is not working inglow plug system, all you have to do is hold a heavy gauge wire and jump from input to output lug on glow relay, hold for 10-15 seconds, the get in cab and start truck. That will get you going until you can fix it correctly. Glow plugs draw a fair amount of current, so be careful not to burn your hands on jump wire and use heavy gauge.
 

rmesgt

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Why not just replace the resistors. Just saying they were put there for a reason. Keep it stock and keep it simple. It worked for 36+ years like it is. Soon an unmolested, unhacked CUCV will be a rarity. Do as you wish. The resistors do work a long time and when they fail replace them. Just like other parts. Nothing is infallible. I have a pile of the resistors complete. Bought everyone I seen because I heard they fail. Over 25 years of CUCV's and hundreds of thousands of miles and never had 1 failure. Thus I have lots of spares. Good Luck. Be Safe.
You are, as always, so spot on. I replaced the fried glow plugs with AC Delco 13G's (all eight) and my truck started immediately. I too want to keep my vehicles stock for as long as I can. My next step will be to replace the rectangular fuel filters mounted to the fire wall. I have no idea how long these filters have been on the trucks so I better get them changed before they leave me stranded somewhere.
 

rmesgt

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CUCVRUS.... You were right on the money! All 8 glow plugs were inop. I remember a while ago that I left the key on overnight, which is what probably fried them. New plugs are ordered and should be here by tomorrow AM.
New plugs are in and the truck is running fine. Thank you for the advice...
 

Curtisje

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Many years ago when my resisters fried, I went searching for a new set. I could not find any. At that time, they did not make them anymore. I did not want to take any chances with buying a used set. Hence the bypass.

I agree keeping it all stock is more beneficial.




You just explained what I already explained, but in more of a technical way;-) I did not say consistently. Yes we are both correct.

“To my knowledge, the resister basically resists/converts the 24volt to 12 volt.“

“It drops the voltage to 12v when the glowplug system draws from the system during startup.”
No. You stated
"To my knowledge, the resister basically resists/converts the 24volt to 12 volt. So test each end of the resister. One side should be 24 volt and the other about 12volt. Depends if the motor is on turning the dual alternators.

There are perhaps others that could correct me if I am wrong?"

With that statement one would assume you will get a 12v reading from the output side of the resistor. That is what I believed until someone on this site taught me the truth which is the output side will read 24v. It is a resistor, not a converter.

I corrected you because you were wrong, just like I was wrong in the same way about a year ago in a similar discussion. Someone here corrected me (Antennaclimber, Marcusoreilyus, Dependable, I don't remember) and I took my multimeter out and found out I was wrong.

It is great learning on this site. I hope you enjoy it too.
 

2INSANE

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No. You stated
"To my knowledge, the resister basically resists/converts the 24volt to 12 volt. So test each end of the resister. One side should be 24 volt and the other about 12volt. Depends if the motor is on turning the dual alternators.

There are perhaps others that could correct me if I am wrong?"

With that statement one would assume you will get a 12v reading from the output side of the resistor. That is what I believed until someone on this site taught me the truth which is the output side will read 24v. It is a resistor, not a converter.

I corrected you because you were wrong, just like I was wrong in the same way about a year ago in a similar discussion. Someone here corrected me (Antennaclimber, Marcusoreilyus, Dependable, I don't remember) and I took my multimeter out and found out I was wrong.

It is great learning on this site. I hope you enjoy it too.
I said resist.

For educational reasons, would you be willing to make a video while testing your resister without load and under load and share with us?
 

Curtisje

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I said resist.

For educational reasons, would you be willing to make a video while testing your resister without load and under load and share with us?
No, but you can get more info here.


Post number 5 shows how many amps the starting system draws on my truck.

I don't use the resistors on the firewall anymore.
 

2deuce

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From my experience the system works beautifully as long as all of the components are good. I have disconnected the resister thinking the system had a flaw with the cascading effect ruining the glow plugs, but there is a reason glow plugs, burn out in the 1st place. The reason I found that I overlooked on different trucks, is the connection at the glow plugs itself must be solid on all 8 of them. If you have the original connectors that fit on the end of the glow plugs, they probably should be replaced as the 1st thing, ahead of any other mod, in my opinion. It was noted above that an original CUCV is going to be a rare bird... I think it already is.
 
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