Another GPR question-controls

[Wicked72]

Ive done all the testing so far. my gpr has a red 12v control and pink. with the key on the red has 12v and the gpr with only work with the pink grounded and the truck starts fine. Is the pink supposed to be permanently grounded or is it controlled as well. also the red will not shut off when the light shuts off in the truck I assume thats temperature controlled?

Sorry for beating a dead horse ive searched but wasnt able to find the answers.

[NoRalPh]

I wish I could help you with the colors,, but basically here's how it works.

You know about the Big terminals I'm sure (1 from the Batt, 1 goes To the GPs) and the two small terminals work like this. 1 has 12v from the Ign source, the other goes to the PCM which provides ground, to complete the circuit, energizing the magnetic coil inside to connect the two Big terminals together.

So, if you ground the side that goes to the PCM the relay throws and you're in business!

Thing is, why doesn't the PCM do it for you like it's supposed to? (and I would verify that it's actually Not). It would be one of two things, that either it's actually trying but there's something wrong with the PCMs circuitry (bad PCM) OR it doesn't "think" you need GPs because the engine is already warmed-up. I believe that decision is made based on the EOT (Engine Oil Temp) sensor located in the HPOP res.

Anyway, that's where I'd start the process of figuring-out what's wrong

[Wicked72]

thats the answer I was looking for! Thanks so much. So Ill replace the sensor to give that a try. Is there a way to test the pcm to see if its an issue? I guess another question is the pcm the main on for the truck or is it something thats separate? i looked at the pcms online and for over $300 I think if its the problem ill just bypass it if I can.

[NoRalPh]

Gee, don't just "throw parts" at it and hope to get lucky Sometimes it's something stupid you discover while tracking down stuff...

Yes the PCM is the main computer and they Are expensive. You want to make sure you need one before you buy it. Somewhere, in the connector to it, there is a pin that should be supplying ground for between 30sec and 2min (FORGET the WTS light's ON time they're on for longer than that) when it's cold. You could start with a test light at the relay by putting the clip on the (+) side and see if the light comes on. Then trace that back to the computer itself.

I'm afraid I don't know what the EOT sensor parameters are. You need to find out (Google is the key to everything ) and test it to find if That's the problem. Or maybe it's just disconnected!

This is what mechanics get paid the "big bucks" for at the dealership!

[Wicked72]

Im not going to buy a pcm just a eot in the morning and pick up a new test light. I saw a write up for a pcm bypass. they used a temp sensor and a few other cheap parts to shut off the relay at a given time I think. I wish I could find it again....other then that ill just buy a relay and toggle and trip the pcm side of the GPR. Is the there a pin out or a color code somewhere that I can easily find the line at the pcm for testing?

[NoRalPh]

Before anyone can help you with that you need to post the yr/mdl (something you should Always do when asking for help) because they're not all the same.

You can also use Google to find that for yourself

[Wicked72]

its a 99.5 f350 6spd 7.3

[losfinch]

A guy on ebay has the glow plug relay manual control kits if you want to go that way.

[NoRalPh]

I have this, looks like it's marked GPC (GlowPlugControl?), #13 on the big 42pin connector and #101 to the PCM... maybe? check that though

[Wicked72]

I had a new gpr and a plugs from accurate diesel i hadnt used yet. so i installed them today. never did glow plugs before, isnt as bad as i expected only took 4 hours. i had done the 50 cent fix on the wire harness once before so i knew what needed to be done to get into the VC. when i started to remove the connections from the gpr it completely fell apart!!! it just split in half and and then into pieces! it was a replacement from napa...pos... ill see how the one from accurate works. the plugs were burnt but i havent checked resistance on them yet. what should they each read if they are good? Im going to test everything in the am. the truck started right away after i was all done but i had driven it to pick up anti seize before i got started. its supposed to be in the low 40s tonight so in the am ill give her a crank and troubleshoot if need. then i gotta figure out my high idle issue.. ill more then liely do the manual gpr setup if my pcm is acting up. havent bought an eot sensor yet turns out is the same as the coolant temp sensor.