Ccrm Issue

Discussion in 'SN95 4.6L Mustang Tech' started by onefaststang, Apr 12, 2014.

  1. I have been searching the forums, and it seems every thread dies before the issue is solved.

    I believe I have a CCRM issue.

    Car started acting like it had a miss. I pulled the plugs re-gapped and put them back in. Wires are good.
    Car ran ok for a day, the started acting up again. I noticed that my wideband gauge was going dead lean when it started acting up, and I thought I could hear pinging.

    Then it would straighten up and run ok for a mile or 2 and start all over again.

    Car sat and idled you could hear/feel it missing and af was lean.

    It then blew the fuse for the CCRM.

    I instantly thought fuel pump, so I took my power probe and put power to the fuel pump and it runs fine. Pump comes on, makes no funny noise and will run as long as I hold power to it.

    I have checked pin #15 on the ccrm and it has good ground.
    I can hear the ccrm click when I turn the key on, but shortly after the fuse will pop.

    Where to go from here? I've always been a fox guy so this is all new to me.

    Car is a 97 GT
    full PI conversion. The previous owner did everything to it, so it is kind of a hack job.
  2. removed ccrm.

    put power to pin
    #1 fan runs
    #2 fan runs
    #5 fuel pump runs.

    This leads me to believe my wiring from the ccrm to the pump is fine.

    Is there anything before the ccrm that may also be an issue?
  3. The post does not state which fuse blew. So I'm taking a guess here. For the 96-98 Model year the power for the O2 heaters goes through the PCM. Therefore a problem in the O2 heater circuit will also blow the PCM/CCRM fuse.

    A possible cause is burning of the O2 wiring harness after contact with the hot exhaust. Especially at the rear O2's after exhaust mod.

    Please confirm which fuse blows. Is there any evidence of wiring damage? Confirm if after the fuse blows is there key on 12 volts at the ignition radio interference capacitor?
  4. The fuse the blows in under the dash.
    There is no cover on the box so by my search that is the instrument cluster, pats, ccrm and ignition system.

    There are no rear sensors on the car. I vaguely remember the previous owner mentioning removing the rear sensors. I will have to get the car a little higher up in the air to get any further under it. I could only see the 2 front sensors and the wideband sensor. It is possible the harness for the rear sensors in there and burnt through and I could not see it.

    Like I said, I am finding the previous owner hacked up quite a bit before I got it.
  5. For the 97 model year my Ford reference does not show an I/P Fuse #20. It does show an I/P fuse #18 (20 amp). I/P fuse #18 does indeed power the CCRM coil, Instrument cluster, PATS, AND the ignition system.

    So a problem in any one of the sub-systems could be the culprit.

    Possible this is a coil pack problem, radio interference capacitor, or wiring harness fault. But based upon the misfire symptom, I would start with the coil pack.

    I could see the possibility of a arching spark plug wire causing this. Try this old racer's trick. Run the car in a totally dark location. Look for the blue hue of escaping spark where the spark is arching out. Inspect the spark plug wires for white spots which is evidence of arching.

    Does the fuse blow if the motor isn't running? If so, try disconnecting the low voltage coil pack electrical connector to see if this stops the fuse from blowing.
  6. Cycling the key to the on position a couple times would blow the fuse. Car does not need to run.

    I previously swapped one of the coil packs out thinking that was the problem originally but it made no difference.

    I just swapped the coil that I took out for the other coil. started and ran but still missing then the fuse blew.

    I un-plugged both coil packs and cycled the key a bunch of times and it did not blow..

    Fuse that blows in #18, 20 amp. typo there.
  7. Looks like a smoking gun to me.

    As I understand it there is still one combination of coil pack yet to be tried as well.

    Which cylinders are experiencing the misfire? Did switching the coil pack change the misfire cylinder?
  8. ok,
    first off I was wrong about the number of o2 sensors. There were 4. 2 right before the front cat, 2 right after the front cat.

    It looks like I might have 2 different issues going on.
    The front sensor on the drivers side, the black wire was actually cut and spliced back together poorly. The splice (wires twisted together with electrical tape) had come apart.

    I re-connected and heat shrinked and re-installed. all other o2 sensors look good.

    This still did not fix the problem. I did however narrow it down to the original replacement coil that I had put in. I un-plugged them both fuse does not blow. Plug in pass side only fuse does not blow. Plug in Drivers side only and fuse blows. Swapped that coil out for the original old one and car starts and runs.

    Still has a miss though.

    I do not have a noid light or temp gun to try and find which cylinder is missing unfortunately.
  9. Did an injector pull test.
    Looks like #3 and #5 make no difference in idle. All others it drops off bad.

    These 2 plugs are both on the same coil. When I did this the first time around I thought it was #7 the was missing so it seems it does follow the coil.

    I guess the next logical step is to get a coil pack and see what happens.
  10. Sounds like progress to me. Aren't you glad that you didn't change the CCRM?
  11. Sure am. Glad I have the tools and knowledge of places like this. I have not changed the coil yet. Probably next weekend. I may just go yank then off my wife's explorer and see if that works.
  12. Went out and swapped the coils with the explorer tonight. Only got to take a quick ride but it seems to have fixed the problem. Think I will order a set of the screamin demon coils tonight.
  13. Let's re visit this.
    Car has been running good for 2 weeks with new coil packs.
    This morning on the way to work it started skipping and the fuse popped again.

    It's there something before the coil packs that would cause one to go bad?
  14. How do you know the replacement coils are bad?

    Is the motor well grounded? There's a braided grounding strap from the left hand motor mount to the frame rails. It is clean and connected?

    Did you inspect the wiring harness for signs of damage? Especially the part that runs behind the motor crossing from side to side. Sometimes the metal support brackets will chaff the harness.

    This could be excessive dwell. Possible causes are a grounded coil pack signal return or bad PCM coil driver.
  15. I'm assuming replacement coils are bad based on it did exactly what it did previously. Changed the coil packs and it ran good. It's on the side of the road now so I will check grounds after work. I don't have any way to get under it until I can get it towed home.
  16. Got time to take a look at it today. Had no spark on the drivers side coil pack, cylinders 3 and 8. Both on the same side of the coil.

    Replaced that coil.

    Ran new ground from frame to engine and engine to battery.

    Spark is back. Took it for a ride and it will start to miss again.

    I don't see any chafed wires anywhere. What it's before the coil that would cause it to miss?
  17. Also dtc's are P0353, P0354, P0153 and P0175.
  18. Absolutely nothing but a near straight +12 volts VPWR line. The magic happens when the PCM "grounds" the return line.

    IMO serious thought should be given to a bad PCM or a ground short in the signal return line CAUSING excessive dwell. Recommend using a "noid" tester to see the firing pulse from the low voltage side.

    P0351 Through P0360 - Ignition Coil A through J Primary/ Secondary Circuit Malfunction

    • Open or short in Ignition START/RUN circuit
    • Open coil driver circuit in harness
    • Coil driver circuit shorted to ground
    • Damaged coil
    • Damaged PCM
    • Coil driver circuit shorted to PWR
  19. I was starting to think pcm myself. I guess I will have to try and trace the wiring back to the pcm as well. Probably won't happen tomorrow since its mothers day and all.
  20. I'm guessing it's not as simple as just swapping it with another due to the pats?