02 Gt PCM Flash, Fans won’t stop running

[Savannahlh]

My husbands 02 gt has been pushing about 100 psi to the fuel rail. We’ve changed fuel rail pressure switch, fuel relay switch etc etc. Nothing has worked. Figured it may be a faulty ecm so we got one flashed and now the fans won’t stop running. If it’s not one thing it’s another! I’m at a lost cause.... help please!!

 

[wmburns]

Figured it may be a faulty ecm so we got one flashed and now the fans won’t stop running.

The Mustang uses a "fail safe" cooling control interface to the CCRM. What that means is that in the absence of a signal the default action of the CCRM is to run the fans.

Soooooooooooooooooo. When the cooling fans run all the time, that is a dead give away that the PCM isn't working. Either no power or ground or outright dead.

 

[Savannahlh]

Even though we took out the original and Ford dealership flashed a different one to the car? Still didn’t fix our fuel pressure issue unless this ecm is messed up too? Or I just have another issue completely

 

[Savannahlh]

Also before we got the new ecm the check engine light was on and threw a faulty ecm code. There is no check engine light with the new one

 

[Savannahlh]

Car does run and drive but starts to act up due to the fuel issue

 

[wmburns]

Still didn’t fix our fuel pressure issue unless this ecm is messed up too? Or I just have another issue completely

Still didn't fix the fuel pressure problem??????????? So you don't think that it's possible that the fuel pressure problem isn't external to the PCM?

Has the fuel pump been recently changed in this? I can think of several "possible" causes for excessively high fuel pressure in a 1999-2004. For example a ground faulted fuel pump return line would CAUSE the fuel pump to run at 100% duty cycle all of the time. And just in case you are thinking "wouldn't a ground faulted fuel pump power line blow a fuse?". The supply will blow the fuse. The signal return will cause the pump to run flat out.

In all the time I have been helping people on the forums I have never encountered a DTC code the "said" to change the PCM. If you want good help always post the full DTC codes. There are 1,000's and they each have a story to tell.

Regarding the CCRM and cooling fans. IF the CCRM is powered up AND the PCM is not powered this would cause the cooling fans to run all the time. Note, there are multiple reasons WHY this condition could happen. Tests are needed to narrow down. It would be handy to know IF fuse F2.34, F2.2, and F2.8 with the key off and with the key on while this problem is happening.

1999-2004 MY fuse panel schedule:

1999 Mustang GT with 2001 motor swap, wont fire. Please help

First off thank you for taking the time to read this, I hope that you will be able to help me out in some way to get a 4 month project off the ground and back onto the streets. I'm not a master mechanic but know just a little bit, enough to do your typical maintenance, overhauls, and swaps. I...

www.allfordmustangs.com

 

[Savannahlh]

We changed the fuel pump when we first bought the car, it was never changed in the life of the car. But it was having fuel issues before we ever changed the fuel pump. Since we bought the car I have replaced the ccrm, wiring harness connected to the ccrm and ecm, new mass air flow sensor, throttle position sensor, fuel rail pressure sensor, fuel relay sensor, egr valve, ecm, etc

 

[wmburns]

Just wondering. Are you happy with the "parts changing" method of trouble shooting? Any idea of how much $$ has been spent without a solution?

Let me know when you are ready to perform some detailed tests before the next part is changed.

Your first test is to measure the key off resistance of the trunk mounted Fuel pump Driver module pin #3 (RD/PK) and pin #10 (BN/PK) to a known good ground. Post.

IF the BN/PK (brown/Pink) wire is shorted to ground somewhere in the circuit, this will cause the fuel pump to run at 100% all the time regardless of what the FPDM is commanding. This will cause the fuel pressure to be "off the chart".

Here is some information on an affordable very capable ODB2 scanner with bi-directional support that could prove helpful in providing information to help solve your problem.

ForScan ODB2 scanner w ELM327 USB

ForScan ODB2 scanner w ELM327 USB

While working on your car have you ever wanted: to find an ODB2 operational PID value (say fuel pressure or MAF)? How about graph a PID value over time? Or compare multiple PID's over time? Access a bi-directional PCM control such as test a...

www.stangnet.com