I am trying to fix my starting problems and gonna replace the gp's and gpc i am also wanting to replace the temp sensor for the gp's and havent found anyone that carries it other than ford didnt know if anyone had part number or a place i can order online it is for a 93 7.3 thanks for the help.
glow plug temp sensor
- Thread starter coryfast
- Start date
SKimballC
Registered User
LMC Truck has it. Glow plug heater switch 83-93, Part #43-4250 at $119.95.
i would try just the glow plugs first and make sure the connections are good at the controller. i had a hard starting problem with the light only coming on a few seconds and i could hear the controller clicking. i put in new motorcraft glowplugs and it solved the problem. now the light comes on steady for about 12 seconds and it starts fine. dousent cost any extra to just replace the plugs first unless you know other stuff is bad.
I thought the 7.3l GP system didn't have a separate temp sensor for the glow plugs? I was under the impression that the controller measured the GP resistance and figured out the temp from there?
What am I missing? Where is this sensor located on the engine?
Thanks!
What am I missing? Where is this sensor located on the engine?
Thanks!
I am not sure i am not at home so i cant look so i dont know for sure if it has one i thought i remember reading somewhere about it having a temp sensor in the back of one of the heads if anybody knows for sure i would appreciate the help i have a new gpc and am wainting on my gp's to come in.
The '83-'86 trucks have a "temp sensor" that screws into the driver's side cylinder head...it also serves as the controller. With this setup, the coolant temp affects a bimetallic spring that in turn determines how often and for how long the plugs cycle. The spring tends to stick, however, which can and does burn up the plugs. AFAIK, most people with '83-'86 trucks either changed to a push-button system or upgraded to the '87-'94 controller, for this reason.
Other than that, AFAIK, the only coolant sensors on our trucks are the ones for the temp gauge (on the driver's side head, in the front), the "overheat" light (also in the driver's side head, below the temp gauge), and the cold idle/timing advance solenoids (on the top front of the passenger's side head). A guy at a Ford dealer tried to tell me that the sensor for the cold idle solenoid also influenced the glow plugs, but there's no connection I can find between that circuit and the GP circuit... *shrug*
That said, I upgraded to a 7.3l setup and am having problems with it (plugs only stay on for 1.5 seconds at a time, and don't cycle), so I am concerned that I missed something in the install. Either that, or the controller is REAL sensitive to the gauge/length of the wires going to the plugs
I have a full harness sitting in storage, but haven't had time to dig into it...and the wiring diagrams I've seen don't show any coolant sensors directly tied into the '87-'94 GP circuit...
Other than that, AFAIK, the only coolant sensors on our trucks are the ones for the temp gauge (on the driver's side head, in the front), the "overheat" light (also in the driver's side head, below the temp gauge), and the cold idle/timing advance solenoids (on the top front of the passenger's side head). A guy at a Ford dealer tried to tell me that the sensor for the cold idle solenoid also influenced the glow plugs, but there's no connection I can find between that circuit and the GP circuit... *shrug*
That said, I upgraded to a 7.3l setup and am having problems with it (plugs only stay on for 1.5 seconds at a time, and don't cycle), so I am concerned that I missed something in the install. Either that, or the controller is REAL sensitive to the gauge/length of the wires going to the plugs
I have a full harness sitting in storage, but haven't had time to dig into it...and the wiring diagrams I've seen don't show any coolant sensors directly tied into the '87-'94 GP circuit...
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Mont91
Full Access Member
Quote from Haynes Diesel Engine Repair Manuel.
"Controls glow plug on-time by monitoring their resistance to determine temperature and cycling the current to the glowplugs."
So I would say wire length and size probably make a differance. This is also why grounds are extremely important.
"Controls glow plug on-time by monitoring their resistance to determine temperature and cycling the current to the glowplugs."
So I would say wire length and size probably make a differance. This is also why grounds are extremely important.
SKimballC
Registered User
I had a response that was totally wrong. What is the switch they refer to as a glow plug switch for a 7.3 then?
Last edited:
Mont91
Full Access Member
Sounds like the oil pressure switch to me. The controler is under the back of the breather on a nonturbo and has a slotted plastic cover and is about twice as long as wide. The '87 and up used an electronicaly operated controler that "reads" the resistance in the glow plug system then decides how long to run the glow plugs before start and how long to cycle them after initial warmup.
This "read" assumes a complete and total ground back to battery. If you have 1 ohm or more between the ground wire on the controler and the negetive battery post the controller will not function properly.
This "read" assumes a complete and total ground back to battery. If you have 1 ohm or more between the ground wire on the controler and the negetive battery post the controller will not function properly.
Mont91
Full Access Member
Hi shane, on the turboed 7.3s I believe the controler was relocated to the valve cover, passenger I think. Under the plastic cover there is a solenoid that looks like a starter solenoid and a bar that goes from the top of the solenoid to a lug that has 2 brown wires that go to different banks for the gow plugs.
If the controller is bad, this is what you need:
http://www.dieselfiltersonline.com/Dy-1023-Motorcraft-Glow-Plug-Relay-Dy1023-Dy-1023.aspx
Mine went bad, so I ordered it from the website I linked and all is well now!
http://www.dieselfiltersonline.com/Dy-1023-Motorcraft-Glow-Plug-Relay-Dy1023-Dy-1023.aspx
Mine went bad, so I ordered it from the website I linked and all is well now!
