1990 Suburban ECM-1 fuse blows, again & again :-(

Discussion in 'Tech Discussion' started by CWGRL, Jul 30, 2013.

  1. CWGRL

    CWGRL Member

    Posts:
    40
    Likes Received:
    2
    Joined:
    Sep 27, 2012
    Location:
    SOCAL
    First Name:
    JW
    Truck Year:
    1990
    Truck Model:
    V2500
    Engine Size:
    350
    I can't find my problem, and I'm going crazy. 1990 V2500, normally run perfect. :)

    On the road last month, and it died. get it home, check fuses... ECM 1 blown. replace..turn key to On position... blows again. sometimes blows on crank.

    Before the blow, I could hear fuel pump relay click but no fuel pump prime. I changed the relay and fuel injector relay anyway. still blows.

    I have also changed, distrib & cap, rotor, coil. 3 months ago I changed all sensors.

    I have traced wiring, everything seems OK. Did the process of elimination with sensors, fuel pump, etc. unplug/plug in... still blows.

    What am I missing?

    HELP! :) please Thank you!
     
  2. foamypirate

    foamypirate Full Access Member

    Age:
    27
    Posts:
    3,029
    Likes Received:
    44
    Joined:
    Jul 30, 2010
    Location:
    Pflugerville, TX
    First Name:
    Jake (Mr. Wilson)
    Truck Year:
    1988
    Truck Model:
    R20
    Engine Size:
    6.0L LQ9 - 4L80E
    I can look in my wiring diagram and see what is on that fuse. From there, I would isolate anything that is tied to that circuit, and start checking for shorts to ground with a meter.
     
  3. RetroC10Sport

    RetroC10Sport Super Moderator Staff Member

    Posts:
    16,340
    Likes Received:
    93
    Joined:
    Sep 29, 2010
    Location:
    Austin, Tx/FEMA Region 6
    First Name:
    Jay
    Truck Year:
    1967, 1989, 1991, 1991; 1995; 2005
    Truck Model:
    Ford Mustang; GMC Sierra C1500 SportSide, GMC Syclone; Chevy S10 Blazer, Olds Silhouette; Corvette
    Engine Size:
    200 L6; 5.7, 4.3, 4.3, 3.8, 6.0
    It goes to the ECM. I would start by unplugging the ECM and cleaning the grounds. The wire that we're looking for is pink/black and goes to the Electronic Spark Control; the gauges; the ECM, the fuel injectors; fuel pump relay.

    Does the check engine light come on?

    Chengny will know more, I have the wiring diagram available for download though if you'd like.
     
  4. CWGRL

    CWGRL Member

    Posts:
    40
    Likes Received:
    2
    Joined:
    Sep 27, 2012
    Location:
    SOCAL
    First Name:
    JW
    Truck Year:
    1990
    Truck Model:
    V2500
    Engine Size:
    350
    Thanks everyone for the replies.

    Truck isn't throwing any codes... I will check pink/black & ECM... :Stupid Me:
     
  5. 89Suburban

    89Suburban Full Access Member

    Age:
    43
    Posts:
    22,543
    Likes Received:
    72
    Joined:
    Dec 7, 2010
    Location:
    Southeast PA
    First Name:
    Paw Paw
    Truck Year:
    1990 Chevy Suburban
    Truck Model:
    R-1500
    Engine Size:
    5.7L TBI/700R4/3.73 10 Bolt Auburn L-S /Cat-Back
    1990 Suburban ECM-1 fuse blows, again & again :-(

    :popcorn:


    Posted from hell
     
  6. CWGRL

    CWGRL Member

    Posts:
    40
    Likes Received:
    2
    Joined:
    Sep 27, 2012
    Location:
    SOCAL
    First Name:
    JW
    Truck Year:
    1990
    Truck Model:
    V2500
    Engine Size:
    350
    LMAO... :emotions122:

    I have everything unplugged ECM, electronic spark control, map, IAC, etc...

    and the damn fuse still blows!

    now, I'm going to pull the dash & gauges...

    But, could it be in the steering column, lock cylinder?
     
  7. RetroC10Sport

    RetroC10Sport Super Moderator Staff Member

    Posts:
    16,340
    Likes Received:
    93
    Joined:
    Sep 29, 2010
    Location:
    Austin, Tx/FEMA Region 6
    First Name:
    Jay
    Truck Year:
    1967, 1989, 1991, 1991; 1995; 2005
    Truck Model:
    Ford Mustang; GMC Sierra C1500 SportSide, GMC Syclone; Chevy S10 Blazer, Olds Silhouette; Corvette
    Engine Size:
    200 L6; 5.7, 4.3, 4.3, 3.8, 6.0
    No, not in the lock cylinder as there's no wiring for it, the ignition switch is down the column a little ways.

    You've likely got a pinched wire somewhere or something is shorting out. I my 1991 S10 Blazer, the gages fuse kept blowing because somehow the speedometer wiring got pinched in the transfer case shifter.

    1990 Suburban wiring diagram - right click and save as.
     
  8. dhamp

    dhamp Full Access Member

    Posts:
    1,172
    Likes Received:
    0
    Joined:
    Jan 18, 2011
    Location:
    Atlanta Area, GA
    First Name:
    Derek
    Truck Year:
    1987
    Truck Model:
    R-10 Custom Deluxe
    Engine Size:
    350
    If you have a voltmeter with a diode tester, many have a beep to show a short. You can put the vm in that mode then probe the feed to each of the items on that fuse until it beeps. If you don't get any shorts, try to slowly move the wires around. Since it's intermittent, you may have to prod it a little to find the short.
     
  9. CWGRL

    CWGRL Member

    Posts:
    40
    Likes Received:
    2
    Joined:
    Sep 27, 2012
    Location:
    SOCAL
    First Name:
    JW
    Truck Year:
    1990
    Truck Model:
    V2500
    Engine Size:
    350
    Holy Heck! Thank you so much for the diagrams! :worship:

    You made my day! :big_banana_Dance:
     
  10. RetroC10Sport

    RetroC10Sport Super Moderator Staff Member

    Posts:
    16,340
    Likes Received:
    93
    Joined:
    Sep 29, 2010
    Location:
    Austin, Tx/FEMA Region 6
    First Name:
    Jay
    Truck Year:
    1967, 1989, 1991, 1991; 1995; 2005
    Truck Model:
    Ford Mustang; GMC Sierra C1500 SportSide, GMC Syclone; Chevy S10 Blazer, Olds Silhouette; Corvette
    Engine Size:
    200 L6; 5.7, 4.3, 4.3, 3.8, 6.0
    You're very welcome. :)
     
  11. Jims86

    Jims86 Full Access Member

    Age:
    41
    Posts:
    5,495
    Likes Received:
    34
    Joined:
    Aug 3, 2010
    Location:
    Patterson,Ca
    First Name:
    Jim
    Truck Year:
    1986
    Truck Model:
    K10 Suburban Silverado
    Engine Size:
    5.7 TBI
    Unplug the downshift relay as well...I am assuming you have a TH400 3speed trans. its the relay next to the fuel pump relay on the firewall.
     
  12. CWGRL

    CWGRL Member

    Posts:
    40
    Likes Received:
    2
    Joined:
    Sep 27, 2012
    Location:
    SOCAL
    First Name:
    JW
    Truck Year:
    1990
    Truck Model:
    V2500
    Engine Size:
    350
    :-( The only relays on the firewall are the fuel pump & fuel injector relays.

    Would the downshift be somewhere else?
     
  13. RetroC10Sport

    RetroC10Sport Super Moderator Staff Member

    Posts:
    16,340
    Likes Received:
    93
    Joined:
    Sep 29, 2010
    Location:
    Austin, Tx/FEMA Region 6
    First Name:
    Jay
    Truck Year:
    1967, 1989, 1991, 1991; 1995; 2005
    Truck Model:
    Ford Mustang; GMC Sierra C1500 SportSide, GMC Syclone; Chevy S10 Blazer, Olds Silhouette; Corvette
    Engine Size:
    200 L6; 5.7, 4.3, 4.3, 3.8, 6.0
    If it has a 700r4 OD trans, it won't have one.
     
  14. Jims86

    Jims86 Full Access Member

    Age:
    41
    Posts:
    5,495
    Likes Received:
    34
    Joined:
    Aug 3, 2010
    Location:
    Patterson,Ca
    First Name:
    Jim
    Truck Year:
    1986
    Truck Model:
    K10 Suburban Silverado
    Engine Size:
    5.7 TBI
    there is no fuel injector relay. just the fuel pump relay, then if it has a similar relay next to it, thats the downshift relay. it has a red, orange, tan/blk, and a purple wire going to it.

    its a v2500....if its a 4l80e, we need to make sure we are looking at the right diagrams.
     
    Last edited: Aug 2, 2013
  15. RetroC10Sport

    RetroC10Sport Super Moderator Staff Member

    Posts:
    16,340
    Likes Received:
    93
    Joined:
    Sep 29, 2010
    Location:
    Austin, Tx/FEMA Region 6
    First Name:
    Jay
    Truck Year:
    1967, 1989, 1991, 1991; 1995; 2005
    Truck Model:
    Ford Mustang; GMC Sierra C1500 SportSide, GMC Syclone; Chevy S10 Blazer, Olds Silhouette; Corvette
    Engine Size:
    200 L6; 5.7, 4.3, 4.3, 3.8, 6.0
    Damn interchange is showing that the V2500 could have a 700r4, but the factory info says otherwise.

    [​IMG]

    See your edit. 4L80E did not come out until 1991. Let me look at the compnine info I have and see what it says, could have been a late year option.

    Compnine says no 4 speed auto R or V 2500s. So I get schooled as well! [​IMG]
     
    Last edited: Aug 2, 2013

Share This Page