Where is my GPR...??....

 

Take the cover off the top of the engine and you will see a relay with some heavy wires coming off of it. looking at the engine it sits kinda up to the left side of the filter housing.
--------------Jeremy

 

dont feel stupid if you dont ask you will never find out . it is next to the fuel bowl top of the pass side valve cover looks like the one that goes to the starter

 

thanks...thought is was that....but wasn't sure....I could hear it click...so was pretty sure.........just dind't want to do something wrong

Yukonsly

 

yuknosly, what is the status on the new injectors, gauges, and TW chip that you had coming? Come on dude, don't keep quite, let us know how it's going!!!!!!!

 

April 16th...INSTALL DATE!!! Keep you posted!

 

Waiting to hear from you!!! Good Luck!!!

 

OK...so the damn thing seems to work when the truck is warm....but is hit and miss when it is cold.....would it be safe to say it's the oil temp sensor.....don't they just fail and not work?.....when the truck is cold I can turn the key on/off....5-10 times before I hear it click...when it does....BAM!....it starts perfect...any hints?

Yukonsly

 

what is it, gpr109 is the part number at napa. Could be gr109 but it is for sure a 109 glowplug relay. I paid like $25 canadian for it. Also while firing through the reciets at home, $132+tax I had paid for my cam shaft post sensor at international and in canadian funds as well.

 

yukonsly, the way that the GPR works is: one of the small wires to the GPR has constant power all of the time (+12volts), when the PCM turns on the GPR it grounds (-) other small wire to complete the circuit.

To test your GPR, remove the two small wires and see if one small wires is hot "+12v" (it should), see if the other small wire has a ground (it should not), see if one of the big wires is hot (it should be) and the other one is not (it should not be). Turn the key on, one small wire should be hot, the other small wire should be grounded (if so then the PCM is turning on the GPR, if no ground then the PCM is not turning on the GPR "see fix below") If the wires test out hot and ground, turn off the key, re-connect the small wires and trun the key back on. Now you should have both big wires hot (GPR is activated and allowing power to travel through to the glow plugs). If you have no power to the big wire that did not have power, (both should be hot) then the GPR is bad, replace it.

To my understanding (somebody will correct me if I'm wrong) the 94 & 95's turned on the glow plugs everytime the switch is turned on, the 96 & 97's only turned on the glow plugs as the PCM read oil temp and outside baro pressure below a set parameter.
It sounds like your PCM is not turning on your glow plugs.

So one of the easiest fixes for your problem that I have done before is: turn your key on and check to see if you have power on one of the small wires to the GPR. The other small wire should show a ground, if it does not then the PCM is not completing the circuit. Take this wire, cut it, splice into it (I would run two sizes bigger "lower #") and run it to a switch (that you mount in your dash) then to a small 12 volt LED light (color of your choice) then to a good ground. The switch could be a momentary one if you want to hold it in until you start or a regular one (the regular one will keep your glow plugs on until you turn it off, so don't forget to turn it off). Hope this helps.

 

WOH!!!....lots of info....thanks Plowhand....I will have some fun with that late on.....I will read your post 3-4 times again just to make sure I understand it properly....so...regardless of sensors...the GPR should turn on....so i can take those out of the equation?.....Ok....cool....I will give it a go.

Yukonsly

 

Correct, my mechanic friend at the local Ford dealer was the one that told me about the glow plug difference on the 94-95 & 96-97 trucks, when I was trouble shooting one. On the 94-95 trucks the PCM only uses the info from the oil temp and baro sensors to tell how long to keep the glow plugs on; not when to turn them on.

 

Ok...so jsut in case i bought the switch to do the wire fix....I'm gonna test the GPR tonite....should the truck be hot or cold?

Can I do the "fix" even if the PCM is turning it on?....replacing the PCM function by the push button switch?....then never have to worry about it again?....will it also allow my truck to start without engaging the GPR....so when the truck is hot....not turning on the GPs....cause it's hot already?

I can't wait to do this....it's a very annoying issue...truck not starting and all....

Yukonsly

 

The issue being fixed or not will be more evident if the truck is cold.

 

On the 95, hot or cold does not matter, but a cold engine is nicer to work over.

Yes, you can do the "fix" even if the PCM is activating the GPR, (i.e. GPR Control Switch or Override Switch). If you do the "fix" the PCM will no longer be controling the GPR, your switch will.

I used a flip switch and LED. When it's cold, I get in the truck, flip the switch up (on), put on my seat belt, set down my bag or coffee etc., then step on the clutch and turn the key. The LED (mounted through the wait to start instrument cluster) reminds me that my glow plugs are activated and to flip the switch down (off).

This way I do not have to sit and hold a momentary button in. But it's just personal preference. I have installed several of both types, whichever the owner wants.