Electrical I Unplugged The Icv And Everything Died!?

Discussion in 'SN95 V6 Mustang Tech' started by skrape, Nov 3, 2012.


  1. skrape

    skrape New Member

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    My '97 3.8 'vert used to have a tough problem - it was a little hard to start, idled roughly at 400 rpm, and pressing the gas pedal would kill it unless you were very gentle. I had probed the MAF signal and it seems to be fine. I was about to probe the TPS sensor signal...
    And then I had the genius whim to see if unplugging the ICV would change the idle.
    Yeah, it did.
    Instantly, the car died. I heard a faint pop. All the dash lights went out. Turning the key doesn't produce any response at all - no dash lights come on, no turn over, no nothing.
    I checked the fuses in the underhood fusebox and they're all okay.

    Anybody got any idea what I killed?
  2. wmburns

    wmburns SN Certified Technician

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    Yes, likely you blew the EEC/PCM fuse. Note, many model year Mustangs have the EEC and Fuel pump fuse labeled backwards.

    Also check I/P fuse #18. But it's best to check all of the fuses to avoid going on a wild goose chase.

    If the EEC and fuel pump fuse is OK, then you have damaged the CCRM. However, more tests will be needed to rule the CCRM in/out. A good set of wiring diagrams will help a great deal. PM if interested in getting a set for yourself.

    Crank with no start check list from allfordmustangs.com:
    http://please delete me!/forums/4-6l-tech/336452-1997-mustang-wont-ignite.html#2984838

    How to trouble shoot Idle/IAC issues from allfordmustangs.com:
    http://please delete me!/forums/4-6...-dieing-idle-idling-rough-14.html#post2260649
  3. skrape

    skrape New Member

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    wmburns - Thanks much, that's exactly the specific sort of info I was hoping for. I'll get another crack at the car this week and will post results.
  4. skrape

    skrape New Member

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    Where is the PCM fuse? I pulled and visually checked all the fuses in the underhood fusebox and in the box under the steering column, and they're all OK...
  5. wmburns

    wmburns SN Certified Technician

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    Recommend that you get a full Ford service manual with wiring diagrams. This will give you the detailed diagrams for what ever trouble shooting you may do now or in the future. If interested in getting a copy for yourself I maybe able to help. PM if interested.
  6. skrape

    skrape New Member

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    Well it's been a while but there's news: It wasn't the PCM fuse, so I replaced the PCM with a used model from an online retailer - and that fixed this problem.
    Note to self, don't unplug any sensors from a Mustang while it's running - on peril of your PCM's life!
    Thanks WMBurns.

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