Have you actually checked the glow plugs? The GPR cycling doesn't mean anything if the glow plugs are burnt out.
Check here for how to check them.
New Member - 2001 7.3 Crank No Start
Hello,
2001 F350 7.3, Built Auto, 4x4, 285K miles – truck ran great right up until it died in the yard and won’t start. Cranks plenty fast. No CEL. No tach movement. No oil pressure movement. WTS light works. GPR cycles. From the Crank No Start flowchart – replaced the CPS with Ford Dealer sourced unit. No change. Found a wire scrubbed raw on driver’s side valve cover – repaired. No change. Full of oil. Oil in Hpop only down about an inch. Can’t pull any codes – power to DLC, but no comms. Tried three different scanners. Pulled PCM and tested pins 71,97 for KO 12v power – good. Pin 55 12v constant- good. NO GROUND on pins 25,51,77 and 103. I’m guessing my problem with lack of coms on DLC and Crank no start are related to no ground at PCM connector. I’ve removed and cleaned every chassis, engine and frame ground I can find. Where the heck is the primary ground source for the four PCM ground pins? Do they feed through another circuit? Can’t imagine they are ignition dependent. Anyone have a wiring diagram for the 2001 7.3 PCM circuit or know where the ground source might be? Or am I barking up the wrong tree? Truck does have an Edge programmer with a program loaded – however, with no comms on DLC, tuner just says “connecting to bridge” when I plug it in. Haven’t had it plugged in for several years. Truck has been super dependable. This is the first time it’s ever left me hangin’. Read every thread I could find on Crank no start. Looking for suggestions. Thanks in advance for any input! Be well!
2001 F350 7.3, Built Auto, 4x4, 285K miles – truck ran great right up until it died in the yard and won’t start. Cranks plenty fast. No CEL. No tach movement. No oil pressure movement. WTS light works. GPR cycles. From the Crank No Start flowchart – replaced the CPS with Ford Dealer sourced unit. No change. Found a wire scrubbed raw on driver’s side valve cover – repaired. No change. Full of oil. Oil in Hpop only down about an inch. Can’t pull any codes – power to DLC, but no comms. Tried three different scanners. Pulled PCM and tested pins 71,97 for KO 12v power – good. Pin 55 12v constant- good. NO GROUND on pins 25,51,77 and 103. I’m guessing my problem with lack of coms on DLC and Crank no start are related to no ground at PCM connector. I’ve removed and cleaned every chassis, engine and frame ground I can find. Where the heck is the primary ground source for the four PCM ground pins? Do they feed through another circuit? Can’t imagine they are ignition dependent. Anyone have a wiring diagram for the 2001 7.3 PCM circuit or know where the ground source might be? Or am I barking up the wrong tree? Truck does have an Edge programmer with a program loaded – however, with no comms on DLC, tuner just says “connecting to bridge” when I plug it in. Haven’t had it plugged in for several years. Truck has been super dependable. This is the first time it’s ever left me hangin’. Read every thread I could find on Crank no start. Looking for suggestions. Thanks in advance for any input! Be well!
1 - 14 of 14 Posts
Check here for how to check them.
Have not actually checked glow plugs. Can the GPR be responsible for the sudden death? I've both checked glow plugs and replaced them in the past.....just not sure they're related to my no comms from the DLC, no ground at the PCM and abrupt shutdown. Truck was starting and running great....until it abruptly died. Then immediate crank no start. And with no comms, no codes to ponder. I'm still wondering if I've got a broken/faulty ground to the PCM connection as I have no ground on pins 25,51,77 and 103 of the PCM connector. Three of which are connected to the same main chassis ground with the IDM. I haven't seen a CEL with ignition on since this started. WTS lights up and again, activates the GPR. And I do appreciate how important glow plugs are for the 7.3 (I've owned the truck for sixteen years in northern MN). I'd really like to see a wiring diagram for the engine/PCM/IDM circuitry. Not easy to locate. Tried to pay the local Ford dealer for copies.....
I'm going to pull the inner fender well tonight to get better access to the PCM connector and see what the IDM looks like. Midwest salt plays hell on metal and wiring. Cheers!
I'm going to pull the inner fender well tonight to get better access to the PCM connector and see what the IDM looks like. Midwest salt plays hell on metal and wiring. Cheers!
The ground for pins 51, 77 and 103 of the PCM (black/white wire) and the ground for pin 26 of the IDM (black/pink wire) are in the engine compartment next to the fuse box (ID is Ground G-101. PCM pin 25 is grounded separately thru a light blue/yellow wire to ground G-100 which is located on the cowl panel above the fuse box. G-100 also provides ground to the PCM power relay coil.
Those are all the grounds I can find for the PCM, so I don't understand how if those grounds are disconnected you can get a WTS light, unless possibly a ground is being provided through one of the items that the PCM controls.
You may have something bad internally in the PCM assuming you don't find a problem in the wiring harness.
Here's a wiring diagram that may help.
Those are all the grounds I can find for the PCM, so I don't understand how if those grounds are disconnected you can get a WTS light, unless possibly a ground is being provided through one of the items that the PCM controls.
You may have something bad internally in the PCM assuming you don't find a problem in the wiring harness.
Here's a wiring diagram that may help.
Attachments
-
166.7 KB Views: 11
WIRING DIAGRAM!!!! You rock! I'm baffled by the WTS as well. If there's no ground to the PCM - it shouldn't trigger a WTS - should it? I think I'm missing something. Unless as you mentioned, ground is being provided. I talked to a Ford tech that's been around long enough to spend time under a 7.3 hood and his comment about ground was "Ground is ground - shouldn't need the key on or a sensor to be working for there to be ground. Ground is ground". He said if I can't find where the ground is bad "just feed it a new one". Might give that a try to see if I can get the PCM to communicate with the DLC. Feel like I'm throwing darts at the wall until I can pull codes. Thanks again for the diagram!The ground for pins 51, 77 and 103 of the PCM (black/white wire) and the ground for pin 26 of the IDM (black/pink wire) are in the engine compartment next to the fuse box (ID is Ground G-101. PCM pin 25 is grounded separately thru a light blue/yellow wire to ground G-100 which is located on the cowl panel above the fuse box. G-100 also provides ground to the PCM power relay coil.
Those are all the grounds I can find for the PCM, so I don't understand how if those grounds are disconnected you can get a WTS light, unless possibly a ground is being provided through one of the items that the PCM controls.
You may have something bad internally in the PCM assuming you don't find a problem in the wiring harness.
Here's a wiring diagram that may help.
Thank you sir!Here's a Crank no start flowchart...
Can you get eyes on the S106 ground splice and the G101 ground location that feeds these PCM grounds? I can't tell exactly where the S106 splice is, but the Ford Service Manual says: In engine harness, near T/O to PCM. Anyone know what T/O stands for?
An illustration of the G101 location is below.
![]()
![]()
An illustration of the G101 location is below.
Thanks! Haven't seen the top pic before. Appears to be more grounds to the PCM connector than I've been testing. I've found all all the under-hood ground connections (G102, G104, G100, G101) removed and cleaned them. I did get pins 25, 51, 77 and 103 to read ground in the PCM connector last night after cleaning everything. Crank no start condition yet. I still don't have output from the DLC. I need to run that down and get this thing to cough up a code or I'm still throwing darts. Appreciate you!Can you get eyes on the S106 ground splice and the G101 ground location that feeds these PCM grounds? I can't tell exactly where the S106 splice is, but the Ford Service Manual says: In engine harness, near T/O to PCM. Anyone know what T/O stands for?
An illustration of the G101 location is below.
View attachment 188586
View attachment 188587
Today's update: Verified connection between PCM connector and DLC. Power, ground and three wires leading to PCM connector all check out. I've got something wonky in my PCM as I'm still unable to successfully connect anyone's scanner to it (OTC, Bosch, Snap-on, Bluetooth dongle) through the DLC. Nothing communicates with my PCM - still unable to pull codes. Going to send the PCM in for testing/rebuild. Not sure why I love this truck.....it hates me.
It feels that way at times that's for sure. Good to know the wiring between PCM and DLC is intact. What bluetooth dongle and app are you using? I like to push FORScan/FORScan lite as we've had good luck with that application on these trucks.
www.thedieselstop.com
Where do you plan to send that PCM? I've read good things on this forum and on FTE about Diesel Technology of Chattanooga for that service.
FORScan/FORScan Lite How-To Thread
The information presented here describes how to use FORScan and FORScan Lite on our 7.3L trucks, to read diagnostic trouble codes, run self tests, and monitor important engine parameters. Let me know if there is anything you'd like to see here that is not mentioned related to this diagnostic...
www.thedieselstop.com
Where do you plan to send that PCM? I've read good things on this forum and on FTE about Diesel Technology of Chattanooga for that service.
WAIT!!!I've got something wonky in my PCM as I'm still unable to successfully connect anyone's scanner to it (OTC, Bosch, Snap-on, Bluetooth dongle) through the DLC. Nothing communicates with my PCM - still unable to pull codes. Going to send the PCM in for testing/rebuild.
Before you send that PCM off, check the fuse that powers the cigarette lighter. It also provides power to the diagnostic connector and if the fuse is blown, you won't be able to connect to the PCM.
I think he's got power. Are the grounds on that connector good as well? This pic is from a thread that PaysonPSD posted on: SCANNER NOT COMMUNICATING WITH PCM...7.3 - Ford Truck Enthusiasts Forums...Can’t pull any codes – power to DLC, but no comms...
Thanks for this! Sorry for the delay......been out of town for a few days and not working on the truck. All fuses have been checked and rechecked. Still no comms. Goind to check the DLC tonight against the info BWST shared - see what that yields. Pulled inner fender out to accesss IDM and PCM plug in. IDM looks like it's terribly corroded (MN winters). Looks like it might disintegrate if I get too aggressive on removal. Not sure it's related to my problem - but it will be soon! Going to test the 5V circuit (Pin 90?) against each of the sensors on that circuit (unplug each sensor individually and see when 5V returns). Maybe she'll fire if one of them is the culprit. Blood pressures down again - it's just a truck. I have others. Peace all!I think he's got power. Are the grounds on that connector good as well? This pic is from a thread that PaysonPSD posted on: SCANNER NOT COMMUNICATING WITH PCM...7.3 - Ford Truck Enthusiasts Forums
View attachment 188612
1 - 14 of 14 Posts
The Diesel Stop
A forum community dedicated to all Ford Diesel owners and enthusiasts. Come join the discussion about PowerStrokes, performance, modifications, troubleshooting, towing capacity, maintenance, and more!
Full Forum Listing
Top Contributors this Month
View All
John in OkieLand
62 Replies
bugman
57 Replies
Big Horn
45 Replies
