Alternator charges sometimes
Thread Starter
|
New User
Joined: Oct 2005
Posts: 22
Likes: 0
UPDATE_____________
Today while the volts was real low and engine running at full temp I disconnected the glowplug relay, then the volts returned to 13.1 right away. I connected the relay back up and the volts dropped again. So the glow plug relay is coming on even thoe the engine is at full operating temperature. So is it the sensor for the oil temp (i dont think so but i will get a new one on my way home) But if not that what else tells the relay to activate is it the computer. Also I hooked up the computer and no codes have been given so the computer thinks all is good.
P.S. I aslo retested alternator output after disconnecting glow plug relay and it now the alternator tests ok 13.5 volts.
Today while the volts was real low and engine running at full temp I disconnected the glowplug relay, then the volts returned to 13.1 right away. I connected the relay back up and the volts dropped again. So the glow plug relay is coming on even thoe the engine is at full operating temperature. So is it the sensor for the oil temp (i dont think so but i will get a new one on my way home) But if not that what else tells the relay to activate is it the computer. Also I hooked up the computer and no codes have been given so the computer thinks all is good.
P.S. I aslo retested alternator output after disconnecting glow plug relay and it now the alternator tests ok 13.5 volts.
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
UPDATE_____________
Today while the volts was real low and engine running at full temp I disconnected the glowplug relay, then the volts returned to 13.1 right away. I connected the relay back up and the volts dropped again. So the glow plug relay is coming on even thoe the engine is at full operating temperature. So is it the sensor for the oil temp (i dont think so but i will get a new one on my way home) But if not that what else tells the relay to activate is it the computer. Also I hooked up the computer and no codes have been given so the computer thinks all is good.
P.S. I aslo retested alternator output after disconnecting glow plug relay and it now the alternator tests ok 13.5 volts.
Today while the volts was real low and engine running at full temp I disconnected the glowplug relay, then the volts returned to 13.1 right away. I connected the relay back up and the volts dropped again. So the glow plug relay is coming on even thoe the engine is at full operating temperature. So is it the sensor for the oil temp (i dont think so but i will get a new one on my way home) But if not that what else tells the relay to activate is it the computer. Also I hooked up the computer and no codes have been given so the computer thinks all is good.
P.S. I aslo retested alternator output after disconnecting glow plug relay and it now the alternator tests ok 13.5 volts.
I have seen a GPR get stuck operated. Whacked it with a small hammer and it released. Stuck the next time it operated. Had to be replaced.
Thread Starter
|
New User
Joined: Oct 2005
Posts: 22
Likes: 0
The GPR is only 1 month old it was brand new from ford. I think it is good because I had this charging problem prior to replacing the GPR. I believe that once I am started the glow plugs should not come on during operation however mine seems to be doing just that so my computer must be turning it on for some reason. How do I check the computer to make sure it is working properly? No codes show up on scanner.
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Now would be a good time to install the "GPR LED mod".
See: https://www.ford-trucks.com/forums/1...l#post10036920
It's good to have even if you're not using it as a troubleshooting device.
Someday I'm going to re-wire my WTS light to be the actual GPR indicator. It involves pulling the instrument panel and cutting printed circuit board copper traces.
Someday.........
Pop
See: https://www.ford-trucks.com/forums/1...l#post10036920
It's good to have even if you're not using it as a troubleshooting device.
Someday I'm going to re-wire my WTS light to be the actual GPR indicator. It involves pulling the instrument panel and cutting printed circuit board copper traces.
Someday.........
Pop
Thread Starter
|
New User
Joined: Oct 2005
Posts: 22
Likes: 0
New update----I installed new oil temp sensor, then I checked voltage at GPR. Key was on and GPR was stuck on so I disconnected GP enabled ground from PCM and GPR went off. I checked volts 13.9 main in 13.9 at 12 volt switched and 0 to glow plugs and 0 at GP enabled ground post, then when I reconnected the GP enabled ground and checked voltage again 12.3 main in 12.3 at 12 volt switch 0 to glow plug but 6 volts to GP enabled ground I disconnect it again and check volts all is back to 13.9. How and where do I check the GP enabled wire back to computer. It seams to me it has a short and is trying to ground even when its not told to do so? Am I correct in my line of thought?
Postmaster
Joined: Apr 2005
Posts: 2,759
Likes: 0
From: round rock, tx
subscribing
I would also add a new ground wire at starter. I added one with new stater install late last year.
I had been going through a new alternator/starter every year to year and a half.
I am very curious about this GP relay staying on after its initial start up.
I would also add a new ground wire at starter. I added one with new stater install late last year.
I had been going through a new alternator/starter every year to year and a half.
I am very curious about this GP relay staying on after its initial start up.
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
GPR enable (GPC, a ground) is through pin 13 of 42 pin connector and to pin 101 of PCM.
GPR power (VPWR) is through pin 24 of 42 pin connector and to pin 71/97 (???) of PCM.
My eyes aren't what they used to be
. See this schematic to confirm:
GPR power (VPWR) is through pin 24 of 42 pin connector and to pin 71/97 (???) of PCM.
My eyes aren't what they used to be
. See this schematic to confirm:
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
Thread Starter
|
New User
Joined: Oct 2005
Posts: 22
Likes: 0
Sorry about making you dizzy really not my intention. The wire schematic and pinout are wonderful thank you. So today I have checked the glow plug controler output or pin 101 on the pcm pinout. The wire checked out ok both by ohms and by no negative or positive power. But when computer is hooked up and the wire hooked up to GPR I run a start cycle on the motor so it activates the glow plugs then the wire will have 6 to 7 volts showing. Is this normal (not acording to my research)?
Thread Starter
|
New User
Joined: Oct 2005
Posts: 22
Likes: 0
UPDATE--------Through my troubleshooting it seems that the computer is leaving 6 to 7 volts on the 12 volt switchable wire. I have checked our other 7.3 powerstrokes and they do not do this. So my assumption is the computer. Can I swap my computer with one of our other computers that way I can see if my computer is bad or not? If so what years interchange? Mine is a 2000.
Thread Starter
|
New User
Joined: Oct 2005
Posts: 22
Likes: 0
PROBLEM DISCOVERED! After all of my investigation and help from this board and PaysonPSD I have finally found my problem. The switchable wire at the GPR was not switching right this would cause the charging system problems. So my original topic of alternator charging sometimes is wrong, it was still charging but because the switchable wire on the GPR was not switched right it would leave the glow plugs on and caused a small short. PaysonPSD posted the pinout for my computer which allowed me to trace the switchable wire to my pcm and i found nothing wrong with the wire so Today I tried another PCM from another good running 7.3 and like magic my switchable wire worked correctly. So my PCM is bad. Now one last question, Is there any aftermarket NEW pcm's. I have my pcm numbers but how exact with these numbers do i need to be if I was to get a reman pcm. Thanks For all the help.
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
Good troubleshooting. 
Reps sent for this, your perseverance and not taking it to a dealership.
What PCM do you have.
Here are PCMs listed alpha numerically by CODE (second column) for 1994-2002. Wish it were by year. LINK
I have lists by either Code, Year or Type for 1999 to 2002 but they are spreadsheets in .xlr format (MS Works) and can't upload them here.
EDIT : If you can't find a PCM or don't want to buy one you can always supply the power through a momentary switch (so you dont leave it on) and manually operate the GPR.
Reps sent for this, your perseverance and not taking it to a dealership.What PCM do you have.
Here are PCMs listed alpha numerically by CODE (second column) for 1994-2002. Wish it were by year. LINK
I have lists by either Code, Year or Type for 1999 to 2002 but they are spreadsheets in .xlr format (MS Works) and can't upload them here.
EDIT : If you can't find a PCM or don't want to buy one you can always supply the power through a momentary switch (so you dont leave it on) and manually operate the GPR.