M1008 resistor

[FMJ]

Ok now that I figured this out (look at page 2) one last question. Can I run a 10 gau wire straight from the negative post of the battery closest to the firewall (this is 12v) straight to the relay and still have the card control the plugs, totally bypassing the resistor or will this disrupt the function of the card?

I did this to my M1008 using the 60G glow plugs, works great for me.

 

[romistre89]

thank you

 

[mangus580]

Yes...

I will restate, I am pretty confident the resistor cant fail in such a mode... unless its highly visible. Can you take a picture or 2 of your resistor please?

 

[Crash_AF]

The shorter run would be to take some 10Ga wire from the two post diamond shaped terminal block above the relay since it is 12V.

Later,
Joe

 

[85-m1028]

I would like to point out that doing so will place the entire glow plug "load" on one battery, not saying it wont work just that it may kill that battery. Even the civy 12v diesels use two batteries..

 

[FMJ]

I would like to point out that doing so will place the entire glow plug "load" on one battery, not saying it wont work just that it may kill that battery. Even the civy 12v diesels use two batteries..

I had mine set up that way for a year, not saying it's not a consideration, but I didn't have a problem.

 

[romistre89]

I went to the two post terminal block and used ac 60g plugs, works for now will keep an eye on that battery. Thanks for all the info.

 

[romistre89]

as far as the resistor it looks to be in great shape. no burns or visible damage. I just don't understand why I was getting 24v at the relay and the plugs? I am going to try and get a relay I know works install it and see what voltage I get that will tell me if mine is bad.

 

[Michael]

For what its worth, I have heard rumors of the resistor failing shorted back in the days of the mil-veh mailing list. I have not seen it myself.

I have one truck with the glow plugs hooked up to the 12v bus and 2 that are original. Haven't noticed much difference between them.

 

[mangus580]

If I remember right... (havent looked real close at mine) But the resistor is just a wire wound around a ceramic insulator, correct? If so, the only way it could fail to a full 24v would be for a wire to break off and short out against another.

I think the 'assumption' that its bad has been made many times because with faulty glow plugs, it WILL provide up to full 24v's. Due to the design, you wont see much, if any measurable resistance on it. Keep in mind, glow plugs draw a massive amount. Looking at the specs for the 050 (which is about a 60g equivalent for civvy engines), they can draw as much as 15 amps. (specs seen here http://www.wellmanautomotive.com/pdf/go50.pdf )

Anyone who has a failed resistor... if you want to send it to me, I would love to check it out, and see what happened. The more I learn about the Mil glow plug system for the CUCV's, the more I realize they are really no different from the civvy ones... as far as problematic.

The component that fails on the card is from the same issue. 24v directly to the card for too long... caused by using the system for way too long with bad glow plugs.

 

[devilman96]

Man I really don’t get how these postings turn into this... I don’t mean to offend anyone with this posting but this keyboard cowboy crap is not helping anyone fix anything!

Guys you should be ashamed of yourselves!!! Why has no one made reference to the TM and the trouble shooting steps associated with the glow plug system? Here shortly the next posting will be that his glow plug controller (or worse) has failed due to tinkering.

Most failures on CUCV electrical systems are owner inflicted!!! Put the tools down and pick up the TM!!!

Go get the TM... read the step by step... test exactly as they say... come back and ask if something seems out of place or skewed. 100$ says anyone whom does this will find the problem 97% of the time as long as you have a general knowledge of electrical, meters, testing, mechanics and common sense... If not... Owning a Craftsman tool set you got for Xmas and a CUCV does not qualify you to be under the hood of a MV, you will create more damage than you will do good! Go get help... Take it to someone qualified... but do not start crawling around poking and prodding!!!

As for the rest of this...

There is no way you’re going to get 24V flowing through a set of these resistors while under load... unless you’re putting about 48V through them, something is wired wrong, your plugs are dead, or you’re not testing them properly. If you’re sitting there with a volt meter hooked to the end of them reading 24V look at the wiring diagram... of course you have 24V on both sides!

If you hook a meter to one end of the resistor and then the other you’re going to get 0 ohms as your testing a dead short. If you didn’t have 0 ohms the resistor would be bad!

If the resistor was bad it would have a nice burned out spot in the windings on one or the other or both but at no time is a bad resistor going to allow a higher than normal voltage to flow across it... it will be LESS or none at all.

Wellman plugs are nothing special... As a matter of fact the TM it's self specs AC Delco 13G plugs. Stop with the wives tails and BS!!! As long as you are using a QUALITY replacement plug your fine!!!

"Glow Plugs. Operate as part of electrical system and assist in engine starting in cold
weather. Temperature self-regulating AC 13G glow plugs preheat air in precombustion chambers
prior to combustion"


The TM also specs testing your glow plugs every 6 months... Resistance should be 1-3 ohms... No one ever does this, one fails, then another and another. Everyone prefers to just keep cranking and prematurely bring their starter or glow plug controller to a early death... usually while blaming the 24V system for being the issue.

Guys this is SIMPLE SIMPLE SIMPLE stuff… I could build one of these wiring harnesses in my sleep! There is nothing complicated about them, they are so primitively put together it’s not funny… basic.. simple.. cheap and VERY effective!!!

GLOW PLUG SYSTEM
NOTE
Glow plug system cycling can be detected by Iistening for clicking at glow
plug relay or by observing voltmeter. Indicator should be to the left of the
normal range during cycling and return to normal range after cycling.
15. GLOW PLUG MODULE INOPERATIVE
NOTE
The only way to determine if your glow plug module is operating properly is
through testing. The glow plug module should not be replaced until the
following tests are performed.
clean, and
continuity.
Step 1. Disconnect pink wire from fuel injector pump. Remove printed circuit board from
glow plug module. Check each circuit to the glow plug module as described. Trace
any circuit that does not operate properly. (See wiring diagram F-7 or F- If all
circuits operate properly, replace glow plug module. (See paragraph 4-
2-62 Change 2
TM 9-2320-289-20
Table 2-4. Electrical Troubleshooting (Con’t)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Wire Color Key Position Instructions and Normal Results
Purple/white “START“ Approximately 12.0 volts at wire. If voltage
is not correct, trace circuit.
Light blue “ RUN “ Jump wire to ground; glow plug relay
energizes. If relay does not energize, trace
circuit. If circuit is good, replace relay. (See
paragraph 4-
Dark blue
Pink/black
Orange
Yellow
"RUN“
“RUN“
“RUN“
“OFF”
Jump wire to ground; “WAIT” light turns on.
If “WAIT” light does not turn on, replace
bulb. (See paragraph 4-7) If “WAIT” light
still does not turn on, trace circuit.
Approximately 12.0 volts at wire. If voltage
is not correct, trace circuit.
Jump light blue wire to ground;
Approximately 12.0 volts at orange wire. If
voltage is not correct, trace circuit.
800 ohms (minimum) at wire (engine cold).
If resistance is not correct, trace circuit. If
resistance is still not correct, replace glow
plug switch. (See paragraph 3-20)
Black "OFF" 0 ohms at wire. Clean connection and
tighten if not correct.
Pink/black and “OFF” 6-10 ohms between wires. If resistance is
light blue at not correct, replace glow plug relay. (See
glow plug relay paragraph 4-
16. “WAIT” LIGHT INOPERATIVE (ENGINE COLD)
Step 1. Check 20 amp engine control fuse and 20 amp ignition fuse. (See
paragraph 4-12)
Replace fuse if burned out.
2-63
TM 9-2320-28$20
Table 2-4. Electrical Troubleshooting (Con't)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
CAUTION
Do not leave key in "RUN” position for more than 2 minutes. Failure to
follow this caution may resuit in damage to glow plugs.
Step 2. Remove glow plug modu!e. (See paragraph 4- Turn key to “RUN” position. Using
jumper wire, ground dark blue lead.
If “WAIT” light turns on, turn key to “OFF” position, reinstall glow plug module,
and perform step 3.​

If “WAll

​

​

-” light does not turn on, replace bulb. If “WAIT” light still does not turn​

cm, trace circuit. (See wiring diagram F-7 or F-

Step 3. Turn key to “RUN” position. Disconnect connector from glow plug switch on upper

left rear of cylinder head.
If “WAIT” light turns on, replace glow plug switch. (See paragraph 3-20)
If “WAIT” light does not turn on, perform ​

​

Electrical Troubleshooting malfunction​

#15​

17. “WAIT” LIGHT ON CONTINUOUSLY WITH KEY IN “RUN” POSITION

Step 1. Remove glow plug module
If “WAIT” light stays on, trace circuit through dark blue lead to “WAIT” light.
(See wiring diagram F-7 or F-
If “WAIT” light goes out, perform ​

Electrical Troubleshooting malfunction #15.​

18. "WAIT” LIGHT OPERATES UPON RESTARTING (ENGINE HOT)

Step 1. Check connections at glow plug switch on upper left rear of cylinder head and glow

plug module.
If connections are not good, clean and secure all connectors.
If connections are good, perform ​

Electrical Troubleshooting malfunction #15.​

19. ENGINE CRANKS BUT WILL NOT START; ENGINE COLD; “WAIT” LIGHT OPERATES

Step 1. Ensure that key is in “OFF” position. Check for voltage between glow plug relay

terminal where orange lead connects and ground.
If there ​

IS voltage, replace glow plug relay (see paragraph 4- and perform​

step 3.

If there is no voltage, perform step 3.

​

​

2-64 Change 2

TM 9-2320-289-20
Table 2-4. Electrical Troubleshooting (Con’t)
MALFUNCTlON
TEST OR INSPECTlON
CORRECTIVE ACTlON
CAUTION
DO NOT leave key in “RUN” position for more than 2 minutes. Failure to
follow this caution may result in damage to glow plugs.
Step 2. Turn key to “RUN” position. Check for voltage between glow plug relay terminal
where orange lead connects and ground.
NOTE
Glow plugs will cycle to 0 volts in approximately 20 seconds after first
operation. Time will shorten as glow plugs become hotter.
If there are 10.0-15.0 volts, ensure that engine is mechanically sound and fuel
system is operating properly,
If there are 22.0-28.0 volts, perform step 3.
If there is no voltage, perform step 4.
Step 3. Disconnect each glow plug lead and check for resistance between glow plug terminal
and ground. Resistance should be 1-3 ohms. Check glow plugs for looseness or
damage.
If any glow plug does not have correct resistance or is damaged, replace, (See
paragraph 3-20) Tighten any loose glow plugs.
Step 4. Tag and disconnect all glow plug leads from glow plugs. Check for voltage between
glow plug relay terminal where red lead connects and ground.
If voltage is 10.0-15.0 volts, connect glow plug leads and start engine.
If voltage is 22,0-28.0 volts, perform step 5.
If there is no voltage, trace circuit back to positive terminal board. (See wiring
diagram F-7 or F-
Change 2 2-65
TM 9-2320-289-20
Table 2-4. Electrical Troubleshooting (Con’t)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
WARNING
Resistor may be hot. Use care when performing this step or injury to
personnel may occur.
Step 5.
Step 6.
Step 7.
Step 8.
Disconnect batteries, pull out bracket and resistor assembly (see paragraph 4-44,
REMOVAL, step 4), disconnect output (red wire) from relay, disconnect input (blue
wire) from input to resistors. Connect positive lead of multimeter to blue wire;
connect negative lead to red wire. Check resistance between resistors and ground.
Resistance should be 0.28 ohms.
If resistance is not correct, replace resistor, connect glow plug leads and
perform step 6.
If resistance is correct, connect glow plug leads and perform step 6.
Check for voltage between glow plug relay terminal where pink/black lead connects
and ground.
If there is voltage, perform step 7.
If there is no voltage, trace circuit. (See wiring diagram F-7 or F-
Check for voltage between glow plug relay terminal where light blue lead connects
and ground.
If there is voltage, perform step 8.
If there is no voltage, replace glow plug relay. (See paragraph 4-
Check for voltage at light blue lead on glow plug module.
If there is no voltage, trace circuit (See wiring diagram F-7 or F-
If there is voltage, perform ​

Electrical Troubleshooting malfunction #15.
2-65.0/(​

 

[Michael]

I apologize if I offended anyone. I will keep my rumors to myself in the future.

 

[85-m1028]

Disconnect batteries, pull out bracket and resistor assembly (see paragraph 4-44,
REMOVAL, step 4), disconnect output (red wire) from relay, disconnect input (blue
wire) from input to resistors. Connect positive lead of multimeter to blue wire;
connect negative lead to red wire. Check resistance between resistors and ground.
Resistance should be 0.28 ohms.
If resistance is not correct, replace resistor, connect glow plug leads and
perform step 6.



Ohhh look whataya know! testing the resistor!! I knew it was in there somewhere, I gave my TM away when I sold my truck.. I guess this "keyboard cowboy" will take his advice else where!!

 

[devilman96]

Michael and 85...

Again guys I'm not trying to insult anyone here... Its just that this issue and about 3 other CUCV electrical issues are posted here almost daily... THE SAME 3 OR 4 PROBLEMS... Over and over and over and over and over. My Gen light... My glow plugs... My start relay... My starter... Ive seen all of them posted thousands of times all because people are lazy... They will not search... they will not read a TM... they will not read other postings... There is a vast amount of knowledge here but as far as CUCV are concerned we might as well not even maintain a data base of prior postings as no one uses them!!!

The flip side... I see so many people posting so much bad, false, or un-intelligent information in response that its becoming fact and then turns into gospel. Glow plugs types are a great example of this!

It needs to be curbed... Were all here to learn, were all here to help... but at the same time ESPECIALLY with CUCV's it seems so many people inflict far more damage than they do good by poking around and playing with wires... its a very bad idea when you don't understand the basic functioning to begin with!!!

A lot of it can be cut short by pointing people to READ TM's FIRST before they keep crawling around and hook a wire back up wrong... Or ... Pointing them to some of the past 6000 posts on the same subject which is pretty much beat like a dead horse... So much so that most of us whom do know very well 'what to do' or 'how to do it' will not even bother reading the posting and/or replying anymore... So when I see a 4 page post on a subject that already has 4000 postings and no one is referencing the most obvious solution to troubleshooting the problem... its time to call shanghais!

So... im sorry if your offended by my posting... but again it's a dead horse!!

 

[85-m1028]

perhaps you can make that TM excerp a sticky and direct all help seekers there??

 

[devilman96]

They are all listed in the CUCV Wiki which will eventually replace the FAQ sticky... But... Good point.

 

[85-m1028]

They are all listed in the CUCV Wiki which will eventually replace the FAQ sticky... But... Good point.

there's nothing in the wiki except some vague references unless there a link I missed, in fact the wiki says the m1008 and m1010 have an open rear diff.

the faq thread has very little info as well check it out, again unless I missed something

I tried to start a thread an paste what you put in it but it wouldn't let me. a little help please!!

anyone??

 

[mangus580]

The wiki is fairly new... needs updating... Feel free to upate/edit info there. Thats the point of the wiki setup.

 

[The Real Highlander]

Man I really don’t get how these postings turn into this... I don’t mean to offend anyone with this posting but this keyboard cowboy crap is not helping anyone fix anything!

Guys you should be ashamed of yourselves!!! Why has no one made reference to the TM and the trouble shooting steps associated with the glow plug system? Here shortly the next posting will be that his glow plug controller (or worse) has failed due to tinkering.

Most failures on CUCV electrical systems are owner inflicted!!! Put the tools down and pick up the TM!!!

Go get the TM... read the step by step... test exactly as they say... come back and ask if something seems out of place or skewed. 100$ says anyone whom does this will find the problem 97% of the time as long as you have a general knowledge of electrical, meters, testing, mechanics and common sense... If not... Owning a Craftsman tool set you got for Xmas and a CUCV does not qualify you to be under the hood of a MV, you will create more damage than you will do good! Go get help... Take it to someone qualified... but do not start crawling around poking and prodding!!!

As for the rest of this...

There is no way you’re going to get 24V flowing through a set of these resistors while under load... unless you’re putting about 48V through them, something is wired wrong, your plugs are dead, or you’re not testing them properly. If you’re sitting there with a volt meter hooked to the end of them reading 24V look at the wiring diagram... of course you have 24V on both sides!

If you hook a meter to one end of the resistor and then the other you’re going to get 0 ohms as your testing a dead short. If you didn’t have 0 ohms the resistor would be bad!

If the resistor was bad it would have a nice burned out spot in the windings on one or the other or both but at no time is a bad resistor going to allow a higher than normal voltage to flow across it... it will be LESS or none at all.

Wellman plugs are nothing special... As a matter of fact the TM it's self specs AC Delco 13G plugs. Stop with the wives tails and BS!!! As long as you are using a QUALITY replacement plug your fine!!!

"Glow Plugs. Operate as part of electrical system and assist in engine starting in cold
weather. Temperature self-regulating AC 13G glow plugs preheat air in precombustion chambers
prior to combustion"


The TM also specs testing your glow plugs every 6 months... Resistance should be 1-3 ohms... No one ever does this, one fails, then another and another. Everyone prefers to just keep cranking and prematurely bring their starter or glow plug controller to a early death... usually while blaming the 24V system for being the issue.

Guys this is SIMPLE SIMPLE SIMPLE stuff… I could build one of these wiring harnesses in my sleep! There is nothing complicated about them, they are so primitively put together it’s not funny… basic.. simple.. cheap and VERY effective!!!

GLOW PLUG SYSTEM
NOTE
Glow plug system cycling can be detected by Iistening for clicking at glow
plug relay or by observing voltmeter. Indicator should be to the left of the
normal range during cycling and return to normal range after cycling.
15. GLOW PLUG MODULE INOPERATIVE
NOTE
The only way to determine if your glow plug module is operating properly is
through testing. The glow plug module should not be replaced until the
following tests are performed.
clean, and
continuity.
Step 1. Disconnect pink wire from fuel injector pump. Remove printed circuit board from
glow plug module. Check each circuit to the glow plug module as described. Trace
any circuit that does not operate properly. (See wiring diagram F-7 or F- If all
circuits operate properly, replace glow plug module. (See paragraph 4-
2-62 Change 2
TM 9-2320-289-20
Table 2-4. Electrical Troubleshooting (Con’t)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Wire Color Key Position Instructions and Normal Results
Purple/white “START“ Approximately 12.0 volts at wire. If voltage
is not correct, trace circuit.
Light blue “ RUN “ Jump wire to ground; glow plug relay
energizes. If relay does not energize, trace
circuit. If circuit is good, replace relay. (See
paragraph 4-
Dark blue
Pink/black
Orange
Yellow
"RUN“
“RUN“
“RUN“
“OFF”
Jump wire to ground; “WAIT” light turns on.
If “WAIT” light does not turn on, replace
bulb. (See paragraph 4-7) If “WAIT” light
still does not turn on, trace circuit.
Approximately 12.0 volts at wire. If voltage
is not correct, trace circuit.
Jump light blue wire to ground;
Approximately 12.0 volts at orange wire. If
voltage is not correct, trace circuit.
800 ohms (minimum) at wire (engine cold).
If resistance is not correct, trace circuit. If
resistance is still not correct, replace glow
plug switch. (See paragraph 3-20)
Black "OFF" 0 ohms at wire. Clean connection and
tighten if not correct.
Pink/black and “OFF” 6-10 ohms between wires. If resistance is
light blue at not correct, replace glow plug relay. (See
glow plug relay paragraph 4-
16. “WAIT” LIGHT INOPERATIVE (ENGINE COLD)
Step 1. Check 20 amp engine control fuse and 20 amp ignition fuse. (See
paragraph 4-12)
Replace fuse if burned out.
2-63
TM 9-2320-28$20
Table 2-4. Electrical Troubleshooting (Con't)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
CAUTION
Do not leave key in "RUN” position for more than 2 minutes. Failure to
follow this caution may resuit in damage to glow plugs.
Step 2. Remove glow plug modu!e. (See paragraph 4- Turn key to “RUN” position. Using
jumper wire, ground dark blue lead.
If “WAIT” light turns on, turn key to “OFF” position, reinstall glow plug module,
and perform step 3.


If “WAll




-” light does not turn on, replace bulb. If “WAIT” light still does not turn

cm, trace circuit. (See wiring diagram F-7 or F-

Step 3. Turn key to “RUN” position. Disconnect connector from glow plug switch on upper
left rear of cylinder head.

If “WAIT” light turns on, replace glow plug switch. (See paragraph 3-20)

If “WAIT” light does not turn on, perform







Electrical Troubleshooting malfunction

#15



17. “WAIT” LIGHT ON CONTINUOUSLY WITH KEY IN “RUN” POSITION
Step 1. Remove glow plug module
If “WAIT” light stays on, trace circuit through dark blue lead to “WAIT” light.
(See wiring diagram F-7 or F-
If “WAIT” light goes out, perform





Electrical Troubleshooting malfunction #15.

18. "WAIT” LIGHT OPERATES UPON RESTARTING (ENGINE HOT)

Step 1. Check connections at glow plug switch on upper left rear of cylinder head and glow
plug module.
If connections are not good, clean and secure all connectors.
If connections are good, perform





Electrical Troubleshooting malfunction #15.

19. ENGINE CRANKS BUT WILL NOT START; ENGINE COLD; “WAIT” LIGHT OPERATES

Step 1. Ensure that key is in “OFF” position. Check for voltage between glow plug relay
terminal where orange lead connects and ground.
If there





IS voltage, replace glow plug relay (see paragraph 4- and perform

step 3.

If there is no voltage, perform step 3.





2-64 Change 2
TM 9-2320-289-20
Table 2-4. Electrical Troubleshooting (Con’t)
MALFUNCTlON
TEST OR INSPECTlON
CORRECTIVE ACTlON
CAUTION
DO NOT leave key in “RUN” position for more than 2 minutes. Failure to
follow this caution may result in damage to glow plugs.
Step 2. Turn key to “RUN” position. Check for voltage between glow plug relay terminal
where orange lead connects and ground.
NOTE
Glow plugs will cycle to 0 volts in approximately 20 seconds after first
operation. Time will shorten as glow plugs become hotter.
If there are 10.0-15.0 volts, ensure that engine is mechanically sound and fuel
system is operating properly,
If there are 22.0-28.0 volts, perform step 3.
If there is no voltage, perform step 4.
Step 3. Disconnect each glow plug lead and check for resistance between glow plug terminal
and ground. Resistance should be 1-3 ohms. Check glow plugs for looseness or
damage.
If any glow plug does not have correct resistance or is damaged, replace, (See
paragraph 3-20) Tighten any loose glow plugs.
Step 4. Tag and disconnect all glow plug leads from glow plugs. Check for voltage between
glow plug relay terminal where red lead connects and ground.
If voltage is 10.0-15.0 volts, connect glow plug leads and start engine.
If voltage is 22,0-28.0 volts, perform step 5.
If there is no voltage, trace circuit back to positive terminal board. (See wiring
diagram F-7 or F-
Change 2 2-65
TM 9-2320-289-20
Table 2-4. Electrical Troubleshooting (Con’t)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
WARNING
Resistor may be hot. Use care when performing this step or injury to
personnel may occur.
Step 5.
Step 6.
Step 7.
Step 8.
Disconnect batteries, pull out bracket and resistor assembly (see paragraph 4-44,
REMOVAL, step 4), disconnect output (red wire) from relay, disconnect input (blue
wire) from input to resistors. Connect positive lead of multimeter to blue wire;
connect negative lead to red wire. Check resistance between resistors and ground.
Resistance should be 0.28 ohms.
If resistance is not correct, replace resistor, connect glow plug leads and
perform step 6.
If resistance is correct, connect glow plug leads and perform step 6.
Check for voltage between glow plug relay terminal where pink/black lead connects
and ground.
If there is voltage, perform step 7.
If there is no voltage, trace circuit. (See wiring diagram F-7 or F-
Check for voltage between glow plug relay terminal where light blue lead connects
and ground.
If there is voltage, perform step 8.
If there is no voltage, replace glow plug relay. (See paragraph 4-
Check for voltage at light blue lead on glow plug module.
If there is no voltage, trace circuit (See wiring diagram F-7 or F-
If there is voltage, perform





Electrical Troubleshooting malfunction #15.
2-65.0/(

Okay... went through these test procedures, I have hard copies of all manuals, but I seem to have a different issue I cannot seem to find on here. Used search but most GP issues I found do not address this problem directly as far as I cold find.

84 CUCV M1009, complete with functional radios and intercom system, all US military wiring and harnesses.Original vehicle, original harnesses, colours match on everything so far so it appears to be not screwed with under dash or in engine bay. trailer lights all work when connected. (Other than the resistors have been bypassed and hooked in correctly. 12 v to GP relayq1.) Temp sensor replaced as part of my troubleshooting, as I thought this may be the issue. I have verified with voltmeter that all glow glow plug resistance is correct per TM manual troubleshooting (the above list was much easier then going through all the manuals)

I have new Hillbilly Wizard card, but same problem existed with old card. Have had vehicle since 2015 this is a recent problem.

Vehicle starts correctly, glow plug process works perfectly, goes to low idle with no issues. HOWEVER... if ANY electrical switch is activated (wiper motor, blinker, brake pedal, headlights, etc) is activated the glow plugs immediately try to warm up again. As soon as any of the electrical items are turned off, the warming stops. I can visually verify by watching red LED on card light up, and also hear the GP relay turn on/off. Voltmeter drops slightly, about a 1/32 movement (but stays in green).
if I pull the GP card out as soon as the slow pugs are warm, prior to switch on, there is no issue, vehicle operated with no problems. This is was my only way to verify that it indeed connected to the card in some fashion, since i cannot seem to find what is "telling" the card that it needs to re-start warm up.

I have a list of all 34 ground points on vehicle, and so far have not found any issues yet under dash with rubbed or cut wires, etc.

Other than putting a manual push button momentary switch on the power to the glow plug card so that it only gets power as long as the button is pressed (so I don't have to manual;y remove the card every time) I cannot find what is going on. I would rather not start really taking apart 39 year old harnesses if I don't have to, and I really want to keep this in "original" condition.

However... if the only answer is install the power bypass to the GP card, then so be it. I think the best place to put the button would be on the plastic on the backside of the blinker assembly so it is not obvious 9also wold act as an anti-theft device if you didn't know it was there).

Thanks for patience and any replies.

 

[antennaclimber]

Just as a wild guess.. Check the ground wire that connects from the engine to the fire wall.
Take both sides off and clean the connections.