Need New PCM ?

[Tinkertech]

Hello everyone. I have been a long time reader but never posted. All my questions were answered by others.

I own a 2006 GT 4.6L Mustang, purchased new in 2006, which I believe has developed a PCM / ECM computer Issue.

Computer P/N:
6R3A-12A650-XB
VK-R3609
S/N: SX4B4K1DWYTS
.
Issue:
1) P0053, front O2 heater.
2) P0059 front O2 heater.
3) A/C intermittent operation.
4) MIL light ‘ON’.
5) All faults appeared at the approximately at the same time period.

Diagnostics:
Diagnostics using my Autel MX808 scan tool I obtained the following results:
Both front O2 heaters indicate their current at ~ 1amp, ( not sure if this is a measured current to the heaters or just a signal output from the microprocessor) on my scan tool, but still throws codes. O2 wiring and heaters ohm out correctly. ~ 5 ohms at the PCM connectors (on a Fluke 117). (disconnected from PCM). No opens or shorts to Gnd.
Computer is indicated to be energizing the A/C clutch relay, on the scan tool, but clutch is intermittent in operation. The PCM does not always provide the ground output signal to energize the clutch relay that is in the BEC (fuse / relay box) even though the computer indicates it to be ‘ON’ when viewed from my scan tool. No measured Gnd signal at clutch relay.
I ran a freeze frame on my Autel scanner and I can see the O2 heaters drop out for a couple minutes then come back on. I believe this is when the computer fails and sets the Mil light.
.
Background / Inspection:
I’ve been an qualified engineer / electronics lab tech for over 50 years and decided to inspect the inside of the computer. I was only able to inspect the top of the board due to it being RTV’d down onto the case. I did not attempt to remove it and did not want to send it off to a speciality shop for chemical removal of the RTV and overcoating. (as I have done in the past on boards). Visual inspection revieled that there was no broken or burnt components. No water intrusion or physical abuse. All solder joints on components (on the top side of board) appeared good under a microscope, board has never been worked on before, could not inspect the 3 I/O connectors solder joints for they are on the bottom of the board. (could possibly be intermittent). All connector pins good. All engine compartment Gnds cleaned and Ohm’d out good. All fuses and relays good. All connectors in both PCM and BEC cleaned and inspected. Car battery new, voltage steady and correct, engine On or Off. Alternator good with no excessive AC ripple. (~40mV at battery as shown on my oscilloscope ). Frequency correct, no bad diodes inside alternator.

Internet Search:
Internet search for a 2006 GT 4.6L Mustang indicating same issues, P0053, P0059, A/C intermittent clutch operation, that the PCM / ECM was bad and replacing it resolved all the issues. Don’t know if the computer was repaired or replaced with a new one. I could not find any new units available so I’m now considering having this one repaired if possible.

Question:
Does anyone have any direct experience with any PCM repair or exchange companies that have had a good experience with? Almost all the companies I have researched all have bad ratings. I wish I could just buy a new one but none exists.
Any insight or help would be much appreciated.

Thanks one and all.

 

[8forfun]

I bought mine from these folks:

https://www.fs1inc.com/oem-engine-c...ys-2006-ford-mustang-6r3a-12a650-xb-vdx1.html

Very helpful and easy to deal with. Reasonable prices as well. I even sent my old locked ecu to them later and they reprogrammed it sure cheap. I'll warn you though the shipping info and tracking make you wonder if you'll ever get it'but it does show up. I'll use them again if I have the need.

 

[Juice]

It is very rare for a pcm to fail.
Is there anything common to the O2 circuits and AC?
There is overcurrent protection on most of the circuits. I have seen this first hand. A circuit would shut off, and power back up after maybe 30 seconds, and keep doing that. (I tapped into power I should not have)
My bet is there is nothing wrong with your pcm, and there is another issue.
I would suspect the O2 sensors first before the pcm, however in this case, both bad is not likely. Are the sensors the correct ones for the car?

 

[Tinkertech]

I have owned the car since new. Original O2 sensors. Car only has 62,000 miles. These are the pre cat O2 heaters ( 1-1, 2-1 ). They Ohm out good. ( ~ 3.5 Ohms ). I can see the heaters on both drop out at the same time on my Autel MX808 scanner and after a couple of minutes they come back on. I'm leaning towards bad solder connections on the board. Also the AC has intermittent clutch operation. All symptoms appeared at the same time.

 

[Juice]

I have owned the car since new. Original O2 sensors. Car only has 62,000 miles. These are the pre cat O2 heaters ( 1-1, 2-1 ). They Ohm out good. ( ~ 3.5 Ohms ). I can see the heaters on both drop out at the same time on my Autel MX808 scanner and after a couple of minutes they come back on. I'm leaning towards bad solder connections on the board. Also the AC has intermittent clutch operation. All symptoms appeared at the same time.

I stil think voltage is droping out due to overcurrent protection.
Any work or mods done before the issue popped up?

 

[8forfun]

Could be a poor ground from the PCM to the block/body/frame. You can check the wiring diagrams here

https://iihs.net/fsm/?d=40

 

[Tinkertech]

No rework on electrical system, all grounds are good.
I really wish it was a wiring harness problem.

 

[Tinkertech]

I've already downloaded the wiring system from that sight. Can't find anything in common with the O2 heaters and the AC control.
When the AC goes out the PCM does not send a ground signal to the AC clutch relay to energize it even though my Autel MX 808 scanner indicates that the the PCM is commanding the AC clutch to engage.

 

[Juice]

I've already downloaded the wiring system from that sight. Can't find anything in common with the O2 heaters and the AC control.
When the AC goes out the PCM does not send a ground signal to the AC clutch relay to energize it even though my Autel MX 808 scanner indicates that the the PCM is commanding the AC clutch to engage.

Possible the low pressure switch is shutting off AC. Monitor that if it shows in live data, or you will need to put guages on the AC system. Low pressure switch cuts off AC @30~ish psi to keep the evaporator from freezing up. Or if system is low. High pressure switch will cut off AC for over pressure. I have seen high pressure switches go bad.

 

[Tinkertech]

Don't believe its the pressure switches. My Autel scanner says the AC is engaged but the output ground signal from the PCM to the AC clutch is not there.
Also O2 heaters go out at the same time. P0053 and P0059.

 

[Tinkertech]

All other systems function normally, no other codes. Car runs normally.
Just P0053, P0059 and intermittent AC clutch operation all at the same time.

 

[Tinkertech]

I think that I have troubleshooted it down to the PCM.

Since I'm in this situation, here is the question I'm after.

What I'd like to know is who has gone through the process of buying a used or rebuilt one and what experience did you have. What vendor, good or bad experience?

 

[Juice]

I think that I have troubleshooted it down to the PCM.

Since I'm in this situation, here is the question I'm after.

What I'd like to know is who has gone through the process of buying a used or rebuilt one and what experience did you have. What vendor, good or bad experience?

I have replaced pcm. It will require programming.
PATS you can program with Forscan.
VIN can be programmed on some PCMs with Forscan.
Calibration flash is Dealer or PCM service vendor only. But you can purchase a 3 day license for Ford access, and there is a light version of IDS you can get to program it all yourself. But you need a VCM.
I would go with Flagship1 and get Forscan. Fs1 will send you a ready to go pcm, but PATS will need to be programmed.

 

[Tinkertech]

Did you have good luck with FS1?

 

[Juice]

Did you have good luck with FS1?

I have not used them personally, but have used them at work. Not often, but have not had any complaints.

 

[8forfun]

I used FS1 twice. I ordered the keys with it the first time. I was replacing a locked by a previous owners tuner (why i tune my own now) PCM. Best price and service I could ask for. Less the lack of shipping info I guess. Then I sent the old locked one in and it came back with the previous set of keys programed in for $150. So I have a spare in case I brick mine.

Was all too easy.

 

[Tinkertech]

Can you program your old PATS keys from your old bad PCM to a rebuilt FS1 PCM that does not come with keys using Forscan?

 

[john knox]

I think that I have troubleshooted it down to the PCM.

Since I'm in this situation, here is the question I'm after.

What I'd like to know is who has gone through the process of buying a used or rebuilt one and what experience did you have. What vendor, good or bad experience?

 

[john knox]

i put new pcm in last month in 06 mustang gt , o'reilly auto parts, i would do it different, what i mean by that is find shop that know how to pull tune file, i bought the car with tune didn`t know it had one, so car ran like shit had get stock airfilter box

 

[Tinkertech]

How did the Oriellys Cardone rebuilt computer work out for you. Were you happy with the quality of the unit?