Manual Glow Plug Control Instructions

ikoinu

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Los Angeles, CA
Manual Glow Plug Controller Walkthrough

I'm making this as I have time, so please bear with me. ;-)
I will be marking the pictures and updating them, along with a list of parts & a step-by-step.


Parts:
Ebay Parts:
HMMWV Glow Plug Distribution Box Interface Harness P/N: 12379865 $42.50
24V 200A Automotive Car Relays Starter Relay $15.00
Mil-Spec Vehicle Momentary Switch Push Button Assembly (Bradley Fighting Vehicle) Part # 12308572 $10.00
Wire Ring Terminal Copper 8 AWG Gauge 5/16" Connectors (x4) $8.00
16 gauge Automotive Wire Black 20' $8.00
Car Rubber Grommet Firewall Hole Plug Set $10

Amazon Parts:
InstallGear 8 Gauge 25ft Power/Ground Wire True Spec and Soft Touch Cable $10.00
Split Loom Heat Shield $9.00
(2) 16 Gauge Ring Terminals
(2) 16 Gauge Female Spade Connectors (preferably water-proof)
8 Gauge Barrel Fuse
Zip Ties
Dielectric Grease


Instructions:
1. Open the dog house engine cover, the battery box, and the hood.
Take the Glow Plug Harness and lay it out along the factory one, exactly the same way. You can use zip ties to hold it in place.

2. Remove existing glow plug connectors from glow plugs.
Now would be a great time to replace the fried plugs, I replaced the whole set because of my control box sending 24v continuously to them. I used Kascar for plugs (Glow Plug Engine Assy HMMWV #5614017 $65.20), and you might want a puller if your plugs are swollen (Glow Plug Removal Tool #GPRT $65.65). Additionally, perhaps take the time to install a grounding harness if you haven't done so already although not necessary for this fix (Ground Kit, 4 Wire, A, B, C, D, #535-A1 $56.16).

3. Plug the new harness onto the glow plugs.
There is no specific order, as there is no firing sequence due to not being spark plugs.

4. Find the spot on the drivers side engine firewall for the relay. There is a bolt that holds the existing harness to the firewall. Use that one. No grounding will be necessary as the momentary switch will provide ground actuating the relay and sending 24v to the glow plugs.

5. Cut the metal plug end off the new harness. Strip each wire, then use the Wire Ring Terminals and attach them to the stripped wires, 4 wires to each terminal. It is a good idea to use some Dielectric Grease on all exposed wiring, as this will stop it from corroding the connection.

6. Route the 8 Gauge Power Wire and the 16 Gauge Ground Wire inside the Split Loom from a hole in the battery compartment to the relay, following the existing wiring harnesses. Avoid any direct contact with engine or moving parts, and keep it tight within the frame so it doesn't snag anything off road. Use the zip ties to route it neatly. The Split Loom protects the wires from any shorting or burning on the hot parts of the engine.

7. Cut a small 4"-6" off the 8 Gauge Power Wire. Attach the Barrel Fuse to the end of the wire coming in to the battery compartment, then attach the small piece you cut off onto the other side. Attach the 8 Gauge Ring Terminal to the 8 Gauge Power Wire coming from the Fuse. Also attach the 16 Gauge Ring Terminal to the 16 Gauge Ground Wire. Connect the Positive 8 Gauge Ring to one battery's positive terminal. Connect the 16 Gauge Ring to the other battery's negative terminal.
This gives you 24v. If you connect them both to the same battery you will only have 12v, which won't activate the relay.

8.


Pictures:
Control Box.jpg
The reason why I made this post to begin with.

Momentary Switch Close Up.jpg
Button close up.

Momentary Switch.jpg
Button install. Used a rubber hole plug with the middle cut out. This is an existing hole on mine with a plug in it. Works great.

Relay Close Up.jpg
Relay wiring. 87 is 8 gauge, 24v from the battery. 86 is 24v coming right off of 87. 85 is a ground wire coming off of the momentary push button switch installed in cab. 30 is the secondary glow plug harness I installed. Cut the end off, attach all to 2 ring terminals, non specific (not spark plugs). I will redo the 24v lead connection, it's not good just hanging out there.

Relay Position.jpg
Relay install location.

Battery Compartment.jpg
Messy battery connections. Please note, you will need to connect the 24v lead to one battery's positive, and the negative lead going to the push button switch to the other battery's negative. Otherwise, you'll have 12 volts going to the relay which won't energize it (24v relay). Additional note: Put a fuse from the battery to the 24v lead. Still waiting on the one I ordered. Fire is possible if you don't take this precaution.

Drivers Side Engine.jpg
Secondary glow plug harness zip tied to original.

Wire Routing Closeup.jpg
Shot of the 8 gauge 24v lead and the smaller negative lead that goes to one side of the push button switch. Used some heat shield on it.

Ground Harness.jpg
Good shot of the grounding harness I made grounded to the rear of the block. Attaches to the generator, starter, firewall gauge ground and glow plug controller ground. Not necessary for the manual glow plug controller setup, but highly recommended for HMMWV's.

Wire Routing.jpg
Another shot from the passenger side of the 24v lead routing.

Passenger Side Engine.jpg
Passenger side pic from the cab with the cover removed. Original glow plug harness leads zip tied together.
 
Last edited:

Ray70

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Hello guys. I was wondering if anyone could give some advise on a similar manual glow plug override problem I'm having? A friend with a HMMWV was having issues with his glow plug controller so I used a 24V starter solenoid and rigged it up with a momentary push button and tied the power into the glow plug harness and fed the solenoid from 24V power.
For some reason he seems to be burning up glow plugs like no tomorrow! I checked the wiring and he is only getting 24V to the plugs when pushing the button. He just bought another set of what appear to be military packed and labeled glow plugs, but before I install them, is there an easy way to verify they are 24V and not 12V by mistake? Trying to figure out why he's cooking them!
 

ken

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Yes 24V plugs will have a bullet looking style connector. Most12V will have a flat blade style connector
 

Action

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Are the plugs still getting 24v when the button is NOT being pushed? I would think it best to separate the plugs from the rest of the vehicle if doing a separate switch.
 

ikoinu

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The EESS does a few more things then just light up your glow plugs....
Exactly why I went the route I did.

Did you check that the plug connectors weren't getting 24v constantly before you tied in to the harness? Mine were, that's why I went the separate harness route.
The glow plugs fry because they can't be on for prolonged periods of time.
 

jackson76550

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Exactly why I went the route I did.

Did you check that the plug connectors weren't getting 24v constantly before you tied in to the harness? Mine were, that's why I went the separate harness route.
The glow plugs fry because they can't be on for prolonged periods of time.
I did some destructive testing on a new glow plug. At about 8 seconds on time with a manual controller it will "pop". with my manual controller it takes 3-4 seconds of on time to start the truck.
 

Ray70

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Exactly what I did... I cut the harness to separate it from the controller and used a 24V solenoid and wired direct to a momentary push button.
Seems the problem is there are Glow plugs being sold on ebay as 24V with the correct NSN# but according to an article I read, the seller admits they are actually 12V plugs. So I gave the vehicle owner 2 choices... since he just installed another set... Either I can change the system to run 12V to the plugs or I sent him the link to HummerPartsGuy's glow plug set so he can buy the right ones. Sounds like he's just going to get a set of the real AM general plugs from HPG and be done with it.
 

ikoinu

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Is there a reason to use a new harness other than to go back to factory if wanted?
There are 2, but absolutely not mandatory.

1. Isolate the plugs away from the potential problem that fried them to begin with. Remember, we still want to keep the box in as the others have said.

2. Not messing with the factory harness. It's a good idea to keep the humvee as original as possible (if you are ever looking to resell it) , while modifying it enough to be comfortable and reliable.
The factory harnesses are waterproof, so when you tie in to them you make them less so. Piggybacking another harness was the easiest way I found to not have to do that.
 
Last edited:

shawnshumvee

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Exactly what I did... I cut the harness to separate it from the controller and used a 24V solenoid and wired direct to a momentary push button.
Seems the problem is there are Glow plugs being sold on ebay as 24V with the correct NSN# but according to an article I read, the seller admits they are actually 12V plugs. So I gave the vehicle owner 2 choices... since he just installed another set... Either I can change the system to run 12V to the plugs or I sent him the link to HummerPartsGuy's glow plug set so he can buy the right ones. Sounds like he's just going to get a set of the real AM general plugs from HPG and be done with it.
Hello i know this is an older post, but i was wondering where at did you tie into the O.E.M harness? Did you tap into the 575A wire that's coming out of the engine control cannon plug?

Thank you
 

Ray70

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Geez, trying to go from memory... I believe there was a pretty hefty wire along the firewall supplying power to the controller? I think I cut and spliced into that feed wire, put the 24V solenoid on the flat area near washer bottle, then cut and spliced the output of the solenoid into the fat wire from the controller that runs along the bellhousing and splits into 8 smaller wires feeding the 8 glow plugs.
To activate the solenoid I picked up a switched power source behind the dash somewhere, added an inline fuse holder and ran to a momentary switch, other side of switch goes to solenoid trigger line.
Going strictly from memory so take with a grain of salt if I mis-speak.....
 

shawnshumvee

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Janesville WI
Geez, trying to go from memory... I believe there was a pretty hefty wire along the firewall supplying power to the controller? I think I cut and spliced into that feed wire, put the 24V solenoid on the flat area near washer bottle, then cut and spliced the output of the solenoid into the fat wire from the controller that runs along the bellhousing and splits into 8 smaller wires feeding the 8 glow plugs.
To activate the solenoid I picked up a switched power source behind the dash somewhere, added an inline fuse holder and ran to a momentary switch, other side of switch goes to solenoid trigger line.
Going strictly from memory so take with a grain of salt if I mis-speak.....
No problem. I ran 12 volts threw the 575A which feeds the glow plugs and runs straight Into the PCB. It seems that my glow plug wires are integrated into the main harness. Nevertheless, I ran a hot wire to that wire and my rig fired up instantly. I didn’t use any switch or solenoid I was just testing it and it worked. But it was only 12 volts right from one battery. Is there a reason or a science behind the 24 volt slinoid because some people say the 24 volts overheats the glow plugs? logic tells me that the safe move is to run 12 volts to the GP. I would imagine 12 volts would prolong the life of the GP’s because they are 12 plugs ?Any help would be great.
thanks
 

Budhummer

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What size fuse is in barrel fuse? I’m doing this. I burned out 2 sets of plugs before I realized they were staying on. I was thinking about using a maxi fuse.
 
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