In the same boat but I haven't had time to do much troubleshooting yet. Most of what I read on the subject was pointing to a bad transceiver. Pulling my cluster codes I get a couple codes that also point to a bad transceiver. Tried a used one and no results.

I sent an inquiry to a place in Jacksonville FL that claims to rebuild the PCMs. Got an automated response but no follow up.

Are you having to take the car to the dealer for programming each time you replace the PCM?

I DID find a little nic in the insulation on a wire from the igniting switch. Having those metal plates under the dash where the harness can rub on it is a piss poor design. I guess on that I'm just going to paint it with insulation and make sure it doesn't touch the metal any more.

So far in my web searches I haven't found anyone that had and reported solving the problem except one. That person had relocated the MAF and the wires were stretched and rubbed on his fender. On that one they just replaced a blown fuse and lengthened the wires. Pretty sure that won't be the answer on a stock vehicle.

I have an old Sniper tuner that claims it can disable PATS but I can't get it to communicate with the OBD under the current circumstances. I suppose when I get this going again I will flash the PCM to do that. I returned the car to stock tune several years back and haven't used the tuner in a long while.

 

I have a tool that I can use to reprogram keys on Fords, so I do it at home.

My codes are a little different. I don't have the scan tool in front of me, but I will reply tomorrow once I get the tool and check the reports, and post the exact codes. The big thing I do remember, I had no PATS codes, no transceiver fault codes, no vehicle disabled codes. I had a code for an SCP Data Fault, a code for Invalid Data from Traction Control, and I think one other U series network code.

After following my diagnostic path, I did not find any compromised wiring at the MAF, none at the TPS, and none at the ignition switch. In fact, my diagnosis has kind of stopped due to a combination of too many customer cars, and worse yet, the Mustang has been starting without fail the last 10 or 15 times I have tried it.

My next shot on this, I plan to catch it when it fails again, and then I want to wiggle test the PCM connector. My thought is that I have some compromised solder joints, and if wiggling the connector brings the car back to life, then I either have a problem in the PCM connector, or the PCM itself.

I'll keep you posted on what I find.

Tim

 

My dash cluster codes are D262, Missing SCP message and a 9681, Pats transceiver signal not received.

Funny that it started intermittent then died altogether. Too bad when it dies it cancels communication through the PCM.

What tool are you using to program the keys? How do you get around the rebuilt PCM not having a VIN or Mileage in it? Is the mileage stored in the cluster?

 

The Cardone PCM's I get from AutoZone come pre-flashed with the VIN and mileage already. I use a tool called Forscan to actually do a parameter reset and get the HEC and PATS modules to accept the new PCM. I actually don't have to program the keys that way.

Here is a screen capture direct from my Autel MaxiPro scan tool. The interesting thing here is that the PCM reports NO faults.

Now, here's one from when the PCM refused to communicate. I went in through the ABS module, and pulled the codes that way. In this one, you can see that the PCM is not in the list of modules scanned, so it was basically saying, nope, not gonna happen.

Pretty much the same codes, telling me that when the fault occurs, it's definitely the PCM going offline causing the codes, and from my testing, the PCM has power and ground when it does go offline - so you get power in, but nothing out.

Tim

 

I'm calling another bad PCM at this point.

I played it with it more today, and studied some wiring schematics.

I tried the tried and true wiggle test, and couldn't make the car fault out. Push, pull, tug, twist, you name it, it will start every time. This rules out a wiring fault.

Also, since I have no communication when the fault occurs to the HEC, making it show all dashes on the odometer, and since the fans fire right away, that tells me that the signal FROM the PCM to the CCRM is missing, thus making the fans go to failsafe. With the fact that I cannot create the error by moving wiring, and the fact that I have good power and ground to the PCM, I'm making the call on another bad PCM.

Tim

 

Looks like both of your scans read a Fault 3 on the HEC. Not sure how or if it relates?

Here is a copy and paste from another forum. I forgot to bookmark it so I don't remember where it came from.

Post 1

This is just an FYI for Mustang owners.
I was having problems for several weeks in 2018-19 with my 1999 Ford Mustang GT (V-8). Would crank but only start when it felt like it, would sometimes stall in traffic, would only run for a few seconds after starting, etc. Finally would not start at all. Local Ford dealer thought it was a PATS (Passive Anti-Theft System) problem. Replacing the instrument cluster and PATS transceiver did not help. Finally, they replaced the CCRM (Part #12B577 AA).


Problem solved. Note: on a 99 Mustang, the CCRM is located near the top of the right front fender well. Must remove the wheel and fender liner to access. Also, the only mention of the CCRM I could find in my Official 1999 Ford Mustang Shop Manual was in the Climate Control section (the CCRM has a relay for the A/C) but not a word about it in the Fuel System section even though it has a relay that feeds the fuel pump.

Post 2

Note to anyone else reading this post. I generally try to discourage anyone to change expense parts such as a CCRM on a guess. On the 1999-2004 Model year it's possible to know with a fair degree of confidence if the CCRM is (or isn't working) by testing fuse F2.31, F2.2, F2.8, and the trunk mounted IFS cut off switch for key on power.

Best to use a test light that will "load" the circuit. Use a known good good ground.

IF there's confirmed key on power at fuse F2.2, F2.8 and the trunk mounted IFS switch, then the CCRM is working.

IF there's no power at fuse F2.31, then the problem is in the ignition switch.

OBTW, my Ford 1999 Ford wiring diagrams does show the CCRM on cell 024-008 Electronic Engine Controls

 

Yeah, I have replaced the CCRM.....twice. The second time was warrantying out the first just to make sure it wasn't faulty.

The U1043 code is just a network communication code stating that garbage data for the traction control was received - likely from the PCM. I get that code every single time it fails to start, and does the parlor trick - along with the other two.

I ordered replacement PCM number 4 tonight. We went through records and found that each PCM lived right about 30 days. We're theorizing that bad quality control on the solder joints inside the PCM are to blame. There's some credence to this theory, as the last 3 PCMs were all made in sequence with each other, and inspected by the same guy, on the same day. The thought is, the car gets hot, the car gets cold, the car bounces around a bit, and we're cracking solder joints. Then, you get intermittent hard to trace faults like this - it's the only thing that makes sense when a PCM operates perfectly for around 30 days or so, then all of a sudden starts acting up - I would think if it was a issue my car, I would see it a lot quicker than 30 days.

It's been a little while now, MAYBE we'll get one from a different lot or batch.

Tim

 

Well, this just got interesting.

AutoZone called, and said Cardone doesn't have any more PCM's. Even though the system says they do. So I called Cardone and they confirmed that. I also called their tech line, and explained everything that I had done, and they agreed the PCM was indeed bad.....again.

So, this just got a hell of lot more interesting.....

Tim

 

So, I ordered a used PCM off of ebay, had it flashed to my VIN and mileage, and when it got here, I installed it, and did a parameter reset so the keys would work.

Boom, fired right up on the first shot, and has shown no signs of failing yet. I have driven the car hard, driven it easy, cut a donut, and pressure-washed it. Nothing has made the car fail.

I did make one final check before I replaced it, I did do a voltage drop test on most of the grounds under the hood. These all passed with flying colors, as did the ground from the battery to the body, and from the body to the engine block.

I guess we'll see what happens in 30 days!

Tim