What is the correct part number for the ECU/PCM?

Tiny
ALOHA168
  • MEMBER
  • 1998 FORD ESCORT
  • 2.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 110,000 MILES
My VIN starts with letter P. Do I need to reprogram the ECU/PCM after replacement? My problem with this car was: my radiator fan (low speed) didn't turn on when the temperature was reached, but it turned on when my A/C was on. I thought that was my coolant temperature sensor. I ordered one (correct part) and changed it. After changing the sensor, the car was very hard to start, and it took me several minutes to get it started. Even when it got started and running, it ran very rough. So, I removed the 'new' sensor and put the original sensor back. The car went back to 'normal' but this time neither speed of the radiator fan works (even with A/C on). I thought that my CCRM was bad since it controls both fan speeds with two relays. I bought a Cardone CCRM (new) and replaced it and it's still doing the same thing. Now I suspect that when I replaced my first 'new' coolant sensor which was very hard to start the car and made it run rough it had caused 'damage' to my ECU (feeds the fan power leads). I have not done anything to my car other than changing the coolant sensor. Can you give me some hint in trouble shooting my problem? Lucking I took my car to smog and passed before all these happened. Thank you for your time.
Tuesday, July 19th, 2022 AT 1:11 PM

7 Replies

Tiny
BORIS K
  • MECHANIC
  • 836 POSTS
Hello,

Theory of operation of the cooling fan system.

The electric cooling fan system consists of a fan and electric 2-speed motor attached to the fan shroud. Engine temperature is monitored by the Engine Coolant Temperature (ECT) sensor. Fan is controlled by Constant Control Relay Module (CCRM) with inputs from Powertrain Control Module (PCM). The electric cooling fan is wired to operate only when the ignition switch is in "on" position.

On Escort, when coolant temperature reaches 221°F (105°C) or A/C (if equipped) is turned on, cooling fan motor will turn on.
On all models, when vehicle speed is greater than 45 MPH and coolant temperature is less than 220°F (104°C), cooling fan motor will turn off.

Please look at the diagram attached below, first check the cooling fan fuse, 40A, in the engine compartment fuse box.

How to check fuse.
https://www.2carpros.com/articles/how-to-check-a-car-fuse

How to use test ligh.t
https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

How to use a voltmeter.
https://www.2carpros.com/articles/how-to-use-a-voltmeter

If the fuse is intact, please next check at the CCRM that there is a constant 12V at pin 3, black/orange wire. This can be done by either using a test light or a voltmeter.

Hope this helps.

Cheers, Boris

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Wednesday, July 20th, 2022 AT 2:23 AM
Tiny
ALOHA168
  • MEMBER
  • 52 POSTS
The fan fuse is good. I think my ECU/PCM is 'bad'(needs reset/initialize or reflash) from what happened since I've already replaced the CCRM with a Cardone unit. My A/C will turn on, but the fan will NOT run at all. And the A/C compressor runs rough too. My VIN starts with letter P. If I replace the ECU, do I need to reprogram the ECU/PCM after replacement? I've heard different answers, some say yes and others say no. Can anybody confirm this? My CCRM part number is F8CF-12B577-BA and labeled with a pink letter Z. I have not tried to look for the ECU yet. Do you know by any chance the part number of my ECU? The car listed above is LX, SOHC with VIN P. Thank you.
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Wednesday, July 20th, 2022 AT 12:08 PM
Tiny
BORIS K
  • MECHANIC
  • 836 POSTS
Hello,

From what I can see online the PCM(ECU) part number is F8CF12A650ND.

Have you confirmed that there is 12V present at the CCRM pin 3?
Also, I would suggest checking if the PCM outputs a ground to pin 17. This should happen when the cooling fans are supposed to be switched on.
The switched ground from the PCM is from pin 17, red/black wire.
You can also test if the cooling fans work by supplying your own ground to pin 17 at the CCRM. If 12V is given at pin 3 of the CCRM then the fans should turn on.

To remove the PCM
Disconnect negative battery cable. Remove any component necessary to gain access to PCM. Loosen PCM connector retaining bolt (if equipped). Unplug harness connector from PCM. Remove 2 PCM mounting bolts. Remove PCM cover and PCM. To install, reverse removal procedure.

It is located in the center console area.

See diagram below.

Cheers, Boris
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Thursday, July 21st, 2022 AT 8:48 AM
Tiny
ALOHA168
  • MEMBER
  • 52 POSTS
Thank you for the trouble shooting info. Upon checking on eBay, there are 2 PCM's that will fit my car, F8CF-12A650-NC(EZA2) and F8CF-12A650-ND(EZA3).I'm getting both yes and no answers on reprogramming. Do I need any reprogramming or just 'plug and play'? Before replacing the Pamm, is there any way to reset/reinitialize it without removing it. I think this is more a 'software' issue instead of a hardware issue since I have not messed with any wiring. The only component I replaced was the coolant temp sensor.
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Thursday, July 21st, 2022 AT 1:06 PM
Tiny
BORIS K
  • MECHANIC
  • 836 POSTS
Hello,

Usually a hard battery reset, disconnecting both terminals, and touching them together for about 15 minutes, will fully reset any system on your vehicle.

I still cannot understand how a faulty temperature sensor would affect the PCM software.

It would be best to first access your PCM and check the part number on your original unit.
Not sure if any programming is required

Cheers, Boris
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Friday, July 22nd, 2022 AT 2:28 AM
Tiny
ALOHA168
  • MEMBER
  • 52 POSTS
I finally have time to work on this car. I did a hard battery reset with no change. I was getting 12V at pin 3 of the CCRM. But I was not getting the Ground at pin 17 with the engine running and A/C on. Does that confirm it's a PCM problem? Since the only components are the coolant sensor, the PCM, the CCRM and the fan motor. Did I miss anything I mentioned?

On a side note, I received a replacement CCRM (refurb A1 Cardone) which I swapped out with my original one. After that, my car was very hard to start(exact situation as the first time I swapped out my coolant sensor). Even if I got it started, it'll run very rough and stall. So, I put the original CCRM back but now it does the same thing as the Cardone unit? I think my car is cursed now. I called Cardone and spoke to a 'tech support' person named Troy. I tried to explain to him about the CCRM problem, but he kept telling me my fan relays are not inside the CCRM and they are behind the dash kick panel blah blah blah. (Of course, I gave him my car year and model). I just have to hang up not to waste any more time with a Moron. I have a very simple problem to start with and now it has turned into a big mess.
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Thursday, August 18th, 2022 AT 4:49 PM
Tiny
BORIS K
  • MECHANIC
  • 836 POSTS
Hello,

The CCRM houses both cooling fan relays and the PCM power relay.
The LFC relay, low speed, is switched on via a solid-state relay inside the CCRM.
The PCM will trigger this relay by switching 12V from pin 45 via pink/white wire to pin 14 at CCRM. The solid-state relay will then supply a ground to the LFC relay to trigger it.
The HFC relay, high speed, in turn is triggered by a switched ground from PCM pin 17 via red/black wire to CCRM pin 17.
The PCM relay switches 12V internal in the CCRM to power the relays and outputs 12V at pins 12+24 to the PCM. Red/white and white/red wires (yellow arrows on diagram).
The red/white wire supplies 12V to the idle air control valve and fuel injectors, see image 2
The white/red wire supplies the EVAP purge valve, EVAP vent solenoid valve, both oxygen sensors and MAF sensor.
It would be good to check what voltage is being supplied from pins 12+24 with the vehicle running bad. Constant 12V is supplied by fuel injection fuse via 2 white/green wires to pins 8+10 at the CCRM, see image 3.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester
and
https://www.2carpros.com/articles/how-to-check-wiring

Hope this helps.

Cheers, Boris
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Friday, August 19th, 2022 AT 6:53 AM

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