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  •  » EEC IV Question for BB1, NOS681, TKO, and any others

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    5/11/2022 8:15 AM  #1

    TimC
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    From: Wheaton, Illinois
    Registered: 4/01/2013
    Posts: 876

    EEC IV Question for BB1, NOS681, TKO, and any others

    87 Mustang GT, automatic

    History:
    Parked it last fall running fine. 
    Replaced weak battery with new this spring.

    Symptoms:
    Fuel pump does not prime when ignition key is turned on. (well, it primed for the normal 2 seconds ONCE out of 50 tries and car fired then stalled out when pump subsequently shut off)
    Jumper wire at test port and at fuel pump relay turns pump on, and car fires right up.
    Relays for ecm and fuel pump test ok.
    Fusible links from starter relay test ok.
    I cleaned up grounds at ecm and fp relay.

    Concern:
    Pin 22 of ECM is constantly grounded when key is on, even when engine is not cranking or running (so pump should be running)

    I sent ecm to ECU Exchange for repair, where power supply and leaky capacitors were reportedly replaced.  Same issue persists.

    Request:
    For those of you that may have a spare EEC IV ecm laying around would you be able to measure continuity or resistance between pins 22 and 40 and between pins 22 and 60 for me and report back?  I am suspecting I still have an ecm issue.

    Spring has finally arrived in the midwest (hummingbird at the feeder this morning) and I gotta get this thing out of garage jail.  All suggestions appreciated.
    Tim
     

     

    5/11/2022 3:34 PM  #2

    Bullet Bob
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    From: Montrose, Colorado
    Registered: 4/01/2013
    Posts: 4,887

    Re: EEC IV Question for BB1, NOS681, TKO, and any others

    Tim, I measure 104K ohms  between pins 22 and 40 and infinite between pins 22 and 60.  You should not have steady ground at pin 22 but if you do...the pump should be running...just like it does when you ground pin 22 through the OBD I port.  You might pull the PCM and measure between the two pins with it on the bench.  
     

    "you get what you pay for, good work isn't cheap, and there are NO free lunches...PERIOD!"
     

    5/11/2022 5:22 PM  #3

    Nos681
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    From: Atlantic Mine, Michigan
    Registered: 7/14/2016
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    Re: EEC IV Question for BB1, NOS681, TKO, and any others



    A9L and 073 (A9L) ecm’s are similar to each other.
    About 102k ohms on both.

    Less than .2 ohms for pins 40-60, 60-40 as well.

    Last edited by Nos681 (5/11/2022 5:23 PM)

     

    5/11/2022 5:30 PM  #4

    Nos681
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    From: Atlantic Mine, Michigan
    Registered: 7/14/2016
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    Re: EEC IV Question for BB1, NOS681, TKO, and any others

    Tim, have you tried a different relay for fuel pump?

    Are you getting power to 37/57 when ignition switch is on (ecm/pcm relay)?

    If the relay for ecm doesn’t energize, the fuel pump relay won’t either.

    Last edited by Nos681 (5/11/2022 5:44 PM)

     

    5/11/2022 7:54 PM  #5

    Bullet Bob
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    From: Montrose, Colorado
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    Re: EEC IV Question for BB1, NOS681, TKO, and any others

    Nos681 wrote:

    Tim, have you tried a different relay for fuel pump?

    Are you getting power to 37/57 when ignition switch is on (ecm/pcm relay)?

    If the relay for ecm doesn’t energize, the fuel pump relay won’t either.

    Butt (TS&T) if 37/57 wasn't hot then the FP relay would not close when he grounds 22 at the OBD I port.
     

    "you get what you pay for, good work isn't cheap, and there are NO free lunches...PERIOD!"
     

    5/12/2022 4:33 AM  #6

    Nos681
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    From: Atlantic Mine, Michigan
    Registered: 7/14/2016
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    Re: EEC IV Question for BB1, NOS681, TKO, and any others

    Is it consistently closing contacts in ignition switch to start the whole process?

    Could try leaving the jumper on fuel pump relay and cycle the ignition switch on/off to see if fuel pump relay energizes every time.

    Might be a connection near/in steering column going to ignition switch too.

    Does the 87 have fuel pump relay under driver seat?
    Might want to check wiring there as well.

    Last edited by Nos681 (5/12/2022 4:40 AM)

     

    5/12/2022 8:57 AM  #7

    TimC
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    From: Wheaton, Illinois
    Registered: 4/01/2013
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    Re: EEC IV Question for BB1, NOS681, TKO, and any others

    Thanks for replies & suggestions.  I probably won't get back to this until Tuesday or Wednesday

    Dan, I pulled the drivers seat to get to the fp relay.  I have 3 wires with 12v there when the key is on.  I have not physically tested the ecm relay, but I hear it click when ignition is switched, and I get power at the fp relay, so I think ecm relay is functioning.

       •Thread Starter
     

    5/12/2022 11:13 AM  #8

    TKOPerformance
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    From: Newark, DE
    Registered: 12/15/2014
    Posts: 7,495

    Re: EEC IV Question for BB1, NOS681, TKO, and any others

    TimC wrote:

    Thanks for replies & suggestions.  I probably won't get back to this until Tuesday or Wednesday

    Dan, I pulled the drivers seat to get to the fp relay.  I have 3 wires with 12v there when the key is on.  I have not physically tested the ecm relay, but I hear it click when ignition is switched, and I get power at the fp relay, so I think ecm relay is functioning.

    Power is fine, but I'd check the grounds too.  IME many electrical issues are bad grounds. 

     

    5/17/2022 6:02 PM  #9

    TimC
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    From: Wheaton, Illinois
    Registered: 4/01/2013
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    Re: EEC IV Question for BB1, NOS681, TKO, and any others

    It's alive!  Thanks all!
    He hangs his head and confesses.... when I reinstalled the ecm after repair, I only had a few minutes to try it out, and I neglected to reconnect the ground wire for the ecm and harness.  Once I reconnected that ground this evening, the pump primed and the car fired right up.

    Bob & Dan,  thanks for those pin values.  Mine did not match those values prior to ecm repair, and match those values after repair, so I knew they fixed something, but I was frustrated when the car didn't run.

     

       •Thread Starter
     

    5/17/2022 6:09 PM  #10

    Nos681
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    From: Atlantic Mine, Michigan
    Registered: 7/14/2016
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    Re: EEC IV Question for BB1, NOS681, TKO, and any others

    Glad you were the problem…I mean found the problem.😁

     

    5/17/2022 6:23 PM  #11

    Bullet Bob
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    From: Montrose, Colorado
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    Re: EEC IV Question for BB1, NOS681, TKO, and any others

    Me too, Tim....I mean I too am usually the problem.  Butt (TS&T) now you have first hand experience about how the grounds can mess things up, as TKO recently said.
    BB1
     

    "you get what you pay for, good work isn't cheap, and there are NO free lunches...PERIOD!"
     

    5/18/2022 3:08 PM  #12

    josh-kebob
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    From: Madison, AL
    Registered: 4/06/2013
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    Re: EEC IV Question for BB1, NOS681, TKO, and any others

    Now go drive dat ting...

     

    5/18/2022 5:03 PM  #13

    Nos681
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    From: Atlantic Mine, Michigan
    Registered: 7/14/2016
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    Re: EEC IV Question for BB1, NOS681, TKO, and any others

    You can say that again Josh.

     

     

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