customer threw an autozone pcm in his truck and rewired the trailer plug and came in barley running, after disconnecting his trailer the truck idled normal then wouldnt start back up since then. a different pcm has been installed as well as new batteries and terminal ends (posts were broken and terminal ends were loose) disconnected the intake heater, there is ground and power to obd ii ive checked the pins to the pcm and seems to have power and ground as well key onn and off . I am using ids ford scan tool and snap on scan tool neither communicate , truck cranks over but with there is no power up of fuelpump or injectors, i have also tried a different idm . any ideas?

 

Has either of the new PCM's been flashed with the correct software? I had a similar experience with a pcm from my local Irish mafia. I had it flashed at the dealership and when I picked it up it ran like crap on the way home. I shut it off in the driveway and she was done. Traced the problem to the fuel pump relay not getting ground from the pcm. If I ran a jumper to ground the relay would engage and the truck would run. That told me the p c m was bad or Fords flash either way I returned it and put my original back in that as it turns out didn't have any issues.

 

@mannyford , welcome to the FTE!

Has the trailer wiring been altered at all since it rolled off the factory floor? Could be a short to ground or power in there somewhere that caused havoc with the PCM.

You state "PCM no communication", do you get a WTS light on the dash when turning the ignition from OFF to ON?

Have you checked the main PCM fuse, I believe it is fuse 30 under the dash, or maybe it is a 30A fuse... I cannot remember right now... Also, it might be a different fuse location based on the vehicle having a GEM or VSM.

You state "there is ground and power to obd ii ive checked the pins to the pcm and seems to have power and ground". How did you check for 12v and ground at the PCM?

Check the two thread links below as there is specific pinout information provided by very knowledgeable FTE'rs in there for ground and 12v power information.

https://www.ford-trucks.com/forums/1...l#post20036497

and

https://www.ford-trucks.com/forums/1...l#post20074012

On the scan tool display, are you seeing CPS, ICP, IPR DC and etc as you would expect?

Give us some more details if you can as there are a myriad of possibilities at this point.

 

Correct on both counts actually, it's fuse number 30 and it's a 30 amp

 

I found a wire that had been replaced horribly and followed it to a plug on the passenger side of the trans for the solenoids and there were a few bare wires and the pigtail had even burnt from crossing wires, and to some yes I’m using ids and snap on scan tool but there was no communication to pcm which means I can’t see icp or ipr or any other pid, I specialize in fords and usually good with 7.3 but wiring gremlins sometimes are a blind battle with these things especially when it effects pcm and you can’t plug into it and all the pcm to obd are passing tests

 

Good find! Did repairing the wires and circuits resolve the issues or is the PCM still "not talking to you?"

Yes sir, no communication to the PCM is a undesirable result with a vast number possible causes. We fully understand that you are not capable of reading any PID from the PCM if it is not communicating, which is why we were/are doing our best to help you out. Either way, it sounds like you may have found the issue.

Keep us updated and we are hopeful that a simple circuit repair will get your customer back on the road.

 

Another common issue causing the behavior you've described (power to the pcm, no OBDII communication, and no WTS light which I don't see if you've verified) can be caused by a short to ground on the 5V reference or VRef circuit. This circuit includes the MAP, ICP, EBP, TPS, and CPS sensors. If any of these has an internal short, or shorted due to wire chaffing on the pigtails, it will cause this behavior.

A quick check would be to disconnect each sensor 1x1 while checking pigtails for chaffing and look for the return of the WTS light (and PCM communication with scan tool).

@Sous provides a nice wiring diagram and pinpoint test procedure in this thread: https://www.ford-trucks.com/forums/1...-dead-pcm.html

 

I'm not familiar with the IDS scanner. Does it normally work on 7.3s? These dinosaurs are choosy with communications, many scanners won't work.

 

IDS is the acronym for Integrated Diagnostics Software (some say "System").

This is a Ford sponsored factory dealership scan tool software that works on all Ford vehicles from 1996 through 2018, and select Ford vehicles from 2018 to present.

Using IDS also requires...

1. A Vehicle Communication Module (VCM), or VDMII, or VCMM (some say VCMIII for the final version)

2. A PC laptop or computer validated with minimum hardware requirements

3. An internet connection (periodic is fine, but the interval between connections to the internet cannot be longer than 30 days, or IDS activation is disabled)

4. A valid, current, activated software license (Currently $900.00 per year)

The IDS will appear to work without a current, valid, and activated software license, but vehicle communication will not work.

Ford has moved away from IDS, even though dealerships still utilize IDS to work with older vehicles.

A history of Ford factory/dealership level scan tools is as follows:

NGS - New Generation Star tester, hand held, no PC required, no internet connection required, no activation or validation required, covers 25 model years of Ford/Lincoln/Mercury and many Mazda vehicles from 1984 - 2009

WDS - World Diagnostics System - Proprietary PC, workstation sized, typically on moving cart. Incorporated the European brands that Ford had once acquired a major ownership stake in (Jaguar and Volvo... both later sold), short lived, expensive, cumbersome, and unpopular among dealership service techs who continued to use their handheld NGS tools instead. No longer supported by Ford. Covered approximately 10 years, more or less, of a variety of vehicles, from 1998 - 2008

IDS - (as described at the beginning of this post)

FJDS - Ford J2534 Diagnostics Software - for use with Vehicle Communication Interfaces (VCI) that are SAE J2534 bi-directional communication compatible, used in module reprogramming (such as reflashing a PCM to a different calibration... meaning native epromm reflashing, not emulating or faking via a tune or chip). Ford introduced the FJDS for Ford Module Programming (FMP) 2018 and newer vehicles, yet Ford is already replacing FJDS with...

FDRS - Ford Diagnostics and Repair System - This is Ford's newest and latest way forward. In compatible with model years prior to 2018, the FDRS will likely be what current and future models of electrified Ford vehicles will require to be diagnosed and reprogrammed.

IDS, FJDS, and FDRS are what is found in Ford dealerships today. These are all time based (functionality expires after a period of time) scantool systems that require a subscription to obtain functionality, and further require some certifications (such as locksmith license) to access vehicle security functions. Furthermore, a periodic internet connection is required to maintain the activation of the software license. Additionally, a VCM / VCI and PC hardware are also required.

The factory scan tool that was in use at the time the 7.3L was being produced is the NGS... a stand alone scan tool using software on PCMCIA cards that requires no license, no activation, no internet access, and no computer, phone, tablet, or interface module.

The least expensive way to scan a Ford vehicle is to obtain FORScan, which is distributed by Russians who pirated Ford's scantool software, and developed a user interface to make the software operable on Android devices and PCs.

There are also knock-off IDS VCMs available from China, and sold on eBay and AliBaba.