Results 1 to 7 of 7

Thread: Bad ECM? 90 sc 5 speed

  1. #1
    Join Date
    Dec 2017
    Posts
    5

    Bad ECM? 90 sc 5 speed

    Been working in my sons 90 Thunderbird sc 5speed. Had a terrible diagnosis on this by me. Thought the timing chain jumped, well after I got it all apart it was fine, actually in great shape for 160000 miles. I'll tell you a quick rundown of what it's doing and what I have tried so far.

    He was driving down the road and it just died and he had a friend help him get it back to the house. The first quick checks I did was fuel pressure (40psi), spark (good). Compression good 120 psi. Unplugged cam sensor just to see if it would burp, nothing.

    There is no signal to the injectors. Took crank sensor off bench tested, good. Went through the monotonous rundown off checks to check DIS and coil pack.

    As I'm working on it I keep asking him has he ever noticed the Cooling fan stays on high with ignition on and fuel pump never shuts off. To me this isn't correct. Fuel pump should only come on for a pre-determined time. Checked the relay control module by taking apart and checking diodes and relays and one transistor, they were good.

    I have the ECM apart right now. In circuit all diodes and transistors check good, I have no way of checking the old obsolete Motorola IC's cause I don't have the pin outs. I am leaning towards a bad ECM. Unless someone can steer me differently.

    Being that the case anyone have a ECM?

    How close do I have to be on the numbers for ecm. On one side FOPF-12A650-ALA, on other side printed in pink E9AF-14A625-AA.

    Thanks in advance for your help.

  2. #2
    Join Date
    Dec 2007
    Location
    PNW
    Posts
    6,455
    For no start, see these steps to check: http://mnharms.com/tutorials/disnostart/

    But based on your testing, I'd agree it is most likely the EEC. About the P/N, see: http://www.sccoa.com/forums/showthre...OPF-12A650-ALA

    Did you try to pull codes?
    Last edited by KMT; 12-29-2017 at 12:38 PM.

  3. #3
    Join Date
    Apr 2002
    Location
    Madison, Ohio
    Posts
    17,570
    Unless you already did this, verify the power and ground connections at the EEC. If it is receiving power on the required pins and ground is good, then 99.9% it is an EEC. Not a common failure, but fan and fuel pump on definitely indicate no signal coming from the EEC to the IRCM. The most basic thing an EEC does is turn off the fuel pump and fan (they run constantly in the absence of a signal to tell them to turn off). So that's generally a dead giveaway of a bad EEC unless the EEC simply isn't getting powered properly.

    I have a guaranteed good 90 5spd EEC. Email me at mdkracing@windstream.net if interested in purchasing.
    Quote Originally Posted by Miller View Post
    Ya thats why i tape mine down. People think its bc i dont have a moonroof seal (which is true) but its really to keep my roof from ripping off .
    Email me here.

  4. #4
    Join Date
    Dec 2017
    Posts
    5

    Eec

    Quote Originally Posted by XR7 Dave View Post
    Unless you already did this, verify the power and ground connections at the EEC. If it is receiving power on the required pins and ground is good, then 99.9% it is an EEC. Not a common failure, but fan and fuel pump on definitely indicate no signal coming from the EEC to the IRCM. The most basic thing an EEC does is turn off the fuel pump and fan (they run constantly in the absence of a signal to tell them to turn off). So that's generally a dead giveaway of a bad EEC unless the EEC simply isn't getting powered properly.

    I have a guaranteed good 90 5spd EEC. Email me at mdkracing@windstream.net if interested in purchasing.

    I sent you an email xr7

  5. #5
    Join Date
    Dec 2007
    Location
    PNW
    Posts
    6,455
    About the ECM part number - Rock Auto's listings may help you sort them out.

    See http://www.rockauto.com/en/catalog/f...computer),2896

    Otherwise, I'm certain Dave will make sure you get the right one.
    Last edited by KMT; 12-30-2017 at 07:19 PM.

  6. #6
    Join Date
    Jun 2002
    Location
    SCCoA Member#1257
    Posts
    3,297
    since you said that you took apart the front to check the timing chain, I assume all is good with the harmonic balancer and trigger wheel?
    Current: 1993 SC 5.0L Auto Red, 1994 SC 5-speed Teal, 1995 SC 5-speed Chameleon Blue
    Old: 89 SC auto Twilight Blue, 89 SC stick Titanium, 90 35th stick, 92 Sport 5.0L stick, 94 SC stick Black, 1994 SC Auto Teal
    Also: 1992 Feature Mustang Convertible 5-speed Vibrant Red, 1991 BMW 850i 6-speed Red, 1994 BMW 850CSi 6-speed Red

    www.mamn12.com for your mid-atlantic mn12 needs!

  7. #7
    Join Date
    Dec 2017
    Posts
    5
    Thanks Dave. EEC worked great start up on first crank. Just out of curiosity how would one go about getting my old EEC flashed/reman so I would have a spare?

Similar Threads

  1. New 90 SC speed record
    By WhiteThunder in forum Non Technical Forum
    Replies: 13
    Last Post: 05-20-2009, 03:09 PM
  2. Parting 90 SC Red 5-speed
    By ShawnSC1 in forum Super Coupe Club of Ontario
    Replies: 24
    Last Post: 10-01-2008, 09:04 AM
  3. new to SC's just got a 90' 5 speed. few ?'s
    By slipcoupe in forum New SC Owner Forum
    Replies: 1
    Last Post: 03-05-2004, 08:16 PM
  4. 90 SC 5 speed for sale
    By James McConnell in forum Super Coupe Club of Ontario
    Replies: 6
    Last Post: 10-14-2002, 08:24 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •