My Glow Plug Relay Mod doesn't Work????

djaroast

My Rusting $20000 Bill
I performed the glow plug relay mod to my 06 and the glow plug light is on for a normal time but this cold morning it seemed that it had none of them working and started real hard:censored:I then tested the fuse block for voltage this eve after work with engine cold and it seemed to have no power. Is there some thing else that runs the relay that could be bad? I reafed on all mt solder joints to make sure of good connection when doing the mod......the only thing I wonder about is that their was 6 links in the relay so I relocated all of them not knowing which one was the rite one to leave????? Love my Sprinter.......when it doesn't need work:thinking: when is that?
 

surlyoldbill

Well-known member
The 3 on the "top" (with the power connection) are, from Left to Right, #1 #3 #5. The other side, from Left to Right, are #x #2 #4.

Were any of the fuses blown? You may also have accidentally blown the fuse to the entire module through some sort of mis-connection. I don't know if it's under the steering wheel or under the seat offhand. The module doesn't allow current to the GP's unless you turn the key on to the "run" position.

If all else fails, there is a new design GP module from the factory that resets instead of blowing fuses.
 

autostaretx

Erratic Member
Were any of the glow plugs replaced in concert with the GPM mod?
After all, *something* had to cause the module's links to blow in the first place.

If you didn't fix the root cause (perhaps shorted glow plugs), modding the module ain't gonna make it magically go away...
(there is an OEM fuse upstream of the module)

--dick
 

djaroast

My Rusting $20000 Bill
The 3 on the "top" (with the power connection) are, from Left to Right, #1 #3 #5. The other side, from Left to Right, are #x #2 #4.

Were any of the fuses blown? You may also have accidentally blown the fuse to the entire module through some sort of mis-connection. I don't know if it's under the steering wheel or under the seat offhand. The module doesn't allow current to the GP's unless you turn the key on to the "run" position.

If all else fails, there is a new design GP module from the factory that resets instead of blowing fuses.
Thanks for the order,It did have #1 blown and I know about about key position. Thanks for the help. I will check the fuse
 

djaroast

My Rusting $20000 Bill
Were any of the glow plugs replaced in concert with the GPM mod?
After all, *something* had to cause the module's links to blow in the first place.

If you didn't fix the root cause (perhaps shorted glow plugs), modding the module ain't gonna make it magically go away...
(there is an OEM fuse upstream of the module)

--dick
Yes #1 plug went and I replaced all. I will check for a fuse inside. I did check the 125A fuse
 

surlyoldbill

Well-known member
The wiring harness can get worn through, especially on the steel brake lines below power brake booster, and ground out the wires going to individual GP's. Try disconnecting the connector from that GP, and then see if the fuse still blows. If it does, you have a problem in your wiring harness. You should be able to start in 20 degree weather with just 3-4 GP's, but it might take a few tries.
 

Ciprian

Spark Plugs not allowed!
Make sure that the small connector on the module is locked in place (ie, all the way in). When I modded my module, this small connector was very hard to push all the way in. And when there is no connection to the ECM, no glow plugs work.
 

djaroast

My Rusting $20000 Bill
Make sure that the small connector on the module is locked in place (ie, all the way in). When I modded my module, this small connector was very hard to push all the way in. And when there is no connection to the ECM, no glow plugs work.
Thanks, I will look at that.
 

djaroast

My Rusting $20000 Bill
So all of a sudden all systems are a go, I did not disconnect the battery when I did the modification so I am thinking it took a bit for the brains of the Sprinter to see that the problem was fixed. It starts perfect in the cold and my Aux heater now works again, does it have something to do with the glow plug relay?
 

autostaretx

Erratic Member
does it have something to do with the glow plug relay?
Not that i'm aware of.... but the Aux Heater does require that the fuel tank be at least 1/4 full or more.
If other signals were going astray, it might have taken the "safe" path of not firing up.

--dick
 

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