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  1. #1

    Default Mystery Wires and Questions - 85 Mustang GT

    I've been trying to find a used engine harness for my 85 GT Carb/Manual/AC car, but I haven't had any luck. The repop harness is on backorder until next year. That leads me to the realization that I need to recreate my own harness using the old one and the available wiring diagrams as a guide. That said, I have a number of mystery wires and questions that I'm hoping the experience here can help me identify and answer. I'll create a post in this thread for each question starting with this:

    TEMP SENSOR: What happens to the operation of the engine if I eliminate the temp sensor located in the intake manifold heater hose connector? Will it affect the running condition in some manner?

    Name:  Temp Sensor-A1.jpg
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    Last edited by jayhawk261; 06-09-2021 at 12:27 PM.
    2011 Mustang GT Track Day car
    1985 Mustang Dominator GT

    Previous cars:
    1979 Mustang 5.0 upgraded to a 351W (1987 - 1991)
    1985 Black Mustang GT Dominator T-Top (bought from Bluesfannoz In 1992 sold in 1993 RIP)
    1990 Mustang GT Titanium hardtop w/black leather (1993 - 1994)
    2004 Mustang GT w/a few bolt ons 255 RWHP (2004 - 2006)
    1985 Mustang GT Medium Canyon Red Factory Sunroof 32,000 miles - Sold to the right person (2013 - 2016)

  2. #2

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    Mystery Wire #1: This wire runs from the body harness connector and runs over to the passenger side of the engine. It shares a connector to the body harness with the temp sensor above as well as Mystery wire #2 (below). Any ideas what this is? It hasn't been plugged in, so it isn't required to run.

    Name:  Mystery Wire 1A.jpg
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    2011 Mustang GT Track Day car
    1985 Mustang Dominator GT

    Previous cars:
    1979 Mustang 5.0 upgraded to a 351W (1987 - 1991)
    1985 Black Mustang GT Dominator T-Top (bought from Bluesfannoz In 1992 sold in 1993 RIP)
    1990 Mustang GT Titanium hardtop w/black leather (1993 - 1994)
    2004 Mustang GT w/a few bolt ons 255 RWHP (2004 - 2006)
    1985 Mustang GT Medium Canyon Red Factory Sunroof 32,000 miles - Sold to the right person (2013 - 2016)

  3. #3

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    Mystery Wire #2: This is a single wire running form the body harness connector over to the passenger side of the engine that has 2 connectors in series. This shares the same body harness connector as the temp sensor and Mystery Wire #1 above. Anyone know what this is? Again, these ends have been unplugged and taped up, so the car does not need this to run.

    Name:  Mystery Wire 2A.jpg
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    2011 Mustang GT Track Day car
    1985 Mustang Dominator GT

    Previous cars:
    1979 Mustang 5.0 upgraded to a 351W (1987 - 1991)
    1985 Black Mustang GT Dominator T-Top (bought from Bluesfannoz In 1992 sold in 1993 RIP)
    1990 Mustang GT Titanium hardtop w/black leather (1993 - 1994)
    2004 Mustang GT w/a few bolt ons 255 RWHP (2004 - 2006)
    1985 Mustang GT Medium Canyon Red Factory Sunroof 32,000 miles - Sold to the right person (2013 - 2016)

  4. #4

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    Mystery Wire #3: This connector is located at the driver's frame rail where the other body to engine connectors are. obviously the engine side has been cut off. The connector has been taped up. Does anyone know where this is supposed to go or what it runs?

    Name:  Mystery Wire 3A.jpg
Views: 96
Size:  150.9 KB
    2011 Mustang GT Track Day car
    1985 Mustang Dominator GT

    Previous cars:
    1979 Mustang 5.0 upgraded to a 351W (1987 - 1991)
    1985 Black Mustang GT Dominator T-Top (bought from Bluesfannoz In 1992 sold in 1993 RIP)
    1990 Mustang GT Titanium hardtop w/black leather (1993 - 1994)
    2004 Mustang GT w/a few bolt ons 255 RWHP (2004 - 2006)
    1985 Mustang GT Medium Canyon Red Factory Sunroof 32,000 miles - Sold to the right person (2013 - 2016)

  5. #5

    Default

    If you remove the temp sensor coolant will shoot out the open port. Leave it or replace with a NPT plug.

    I believe #1 is a canister purge solenoid connector.

    No clue on #2.

    #3 is the connector for A/C WOT cut-out switch.
    Thomas

    1985 Mustang GT - Build Thread
    347 (Stock Block, Scat Crank & Rods, Probe Pistons, 11:1 CR, AFR 185's, PP Crosswind Intake, Custom-ground Comp Hyd Roller Cam, Scorpion 1.6 Roller Rockers, Holley 3310-4), T-5, 8.8 w/3.55's, MM SFC's, T/A, PHB, LCA's, Strut Tower Brace, K-Member Brace, Bilstein HD Struts/Shocks, MM/H&R Springs, SN95 5-Lug, Cobra Brakes, '04 Mach 1 Steering Rack

  6. #6

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    I guess I asked for that one!

    More specifically, how will the car's operation be affected by eliminating that sensor from the system? I'll edit my original post too

    Thanks for the info on these. It's helpful!

    Quote Originally Posted by 85MUSTANGTGT View Post
    If you remove the temp sensor coolant will shoot out the open port. Leave it or replace with a NPT plug.

    I believe #1 is a canister purge solenoid connector.

    No clue on #2.

    #3 is the connector for A/C WOT cut-out switch.
    2011 Mustang GT Track Day car
    1985 Mustang Dominator GT

    Previous cars:
    1979 Mustang 5.0 upgraded to a 351W (1987 - 1991)
    1985 Black Mustang GT Dominator T-Top (bought from Bluesfannoz In 1992 sold in 1993 RIP)
    1990 Mustang GT Titanium hardtop w/black leather (1993 - 1994)
    2004 Mustang GT w/a few bolt ons 255 RWHP (2004 - 2006)
    1985 Mustang GT Medium Canyon Red Factory Sunroof 32,000 miles - Sold to the right person (2013 - 2016)

  7. #7

    Default

    Sorry, that one was too easy.

    That particular temp sensor, if I recall correctly, is the one used for controlling certain engine and emissions functions. Its not needed unless you need said functions. Mine is long gone. There is a second temp sensor on the other side of the intake manifold that operates the gauge.
    Last edited by 85MUSTANGTGT; 06-09-2021 at 01:21 PM.
    Thomas

    1985 Mustang GT - Build Thread
    347 (Stock Block, Scat Crank & Rods, Probe Pistons, 11:1 CR, AFR 185's, PP Crosswind Intake, Custom-ground Comp Hyd Roller Cam, Scorpion 1.6 Roller Rockers, Holley 3310-4), T-5, 8.8 w/3.55's, MM SFC's, T/A, PHB, LCA's, Strut Tower Brace, K-Member Brace, Bilstein HD Struts/Shocks, MM/H&R Springs, SN95 5-Lug, Cobra Brakes, '04 Mach 1 Steering Rack

  8. #8

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    Sounds like I can do away with it then. Most of the emissions equipment had been removed before I got the car, but the peripherals such as wiring and solenoids remain. Sounds like I can eliminate that entire section of the harness when making the new one.

    Thanks again!

    Quote Originally Posted by 85MUSTANGTGT View Post
    Sorry, that one was too easy.

    That particular temp sensor, if I recall correctly, is the one used for controlling certain engine and emissions functions. Its not needed unless you need said functions. Mine is long gone. There is a second temp sensor on the other side of the intake manifold that operates the gauge.
    2011 Mustang GT Track Day car
    1985 Mustang Dominator GT

    Previous cars:
    1979 Mustang 5.0 upgraded to a 351W (1987 - 1991)
    1985 Black Mustang GT Dominator T-Top (bought from Bluesfannoz In 1992 sold in 1993 RIP)
    1990 Mustang GT Titanium hardtop w/black leather (1993 - 1994)
    2004 Mustang GT w/a few bolt ons 255 RWHP (2004 - 2006)
    1985 Mustang GT Medium Canyon Red Factory Sunroof 32,000 miles - Sold to the right person (2013 - 2016)

  9. #9
    FEP Power Member bluesfannoz's Avatar
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    Randy have you checked out the harness that came with one of the MSD Ignition boxes I gave you? Don't think it was a direct plugin in but think it had the ignition, coil, and distributor connections. It may save you some of the recreation yourself.
    Steve
    "Taillights in Your Face Jack? You've just been Dominated!"
    # Link to Facebook Dominator Mustang Fans # # Link to Facebook Predator Mustang Fans #
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    Current Stangs: Stangless
    Previously owned:
    84 Black GT, 85 Black T-Top Dominator GT # Link to Restoration Thread # 85 Dominator GT RIP 1995, 85 Predator GT, 83 Dominator GT, 82 Mustang GT

  10. #10

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    Quote Originally Posted by bluesfannoz View Post
    Randy have you checked out the harness that came with one of the MSD Ignition boxes I gave you? Don't think it was a direct plugin in but think it had the ignition, coil, and distributor connections. It may save you some of the recreation yourself.
    It has some connectors on it, but it is a very minimal harness. The connectors that are on it are available, so no sense in cutting up a new Motorsport harness. I've got a plan for the new one that should work out as long as I can get the AC clutch circuit info.

    I tore the dash completely out tonight to get the heater box out to replace the heater core and the evap core, and we're going to patch the holes in the floor while we're in there and the new carpet will go in too.
    2011 Mustang GT Track Day car
    1985 Mustang Dominator GT

    Previous cars:
    1979 Mustang 5.0 upgraded to a 351W (1987 - 1991)
    1985 Black Mustang GT Dominator T-Top (bought from Bluesfannoz In 1992 sold in 1993 RIP)
    1990 Mustang GT Titanium hardtop w/black leather (1993 - 1994)
    2004 Mustang GT w/a few bolt ons 255 RWHP (2004 - 2006)
    1985 Mustang GT Medium Canyon Red Factory Sunroof 32,000 miles - Sold to the right person (2013 - 2016)

  11. #11

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    If anybody is interested, after a fair amount of time spent with my reading glasses, the wiring diagrams, and the EVTM, Mystery wire number 1 appears to be a connector for the TSAD under hood module which I'm assuming was never actually on the car from the factory, so I guess it has been unplugged its whole life. No need for it in the new harness.

    Mystery wire #2 is/are for the fuel vapor solenoids which are long gone from the car. No need for these in the new harness either.
    2011 Mustang GT Track Day car
    1985 Mustang Dominator GT

    Previous cars:
    1979 Mustang 5.0 upgraded to a 351W (1987 - 1991)
    1985 Black Mustang GT Dominator T-Top (bought from Bluesfannoz In 1992 sold in 1993 RIP)
    1990 Mustang GT Titanium hardtop w/black leather (1993 - 1994)
    2004 Mustang GT w/a few bolt ons 255 RWHP (2004 - 2006)
    1985 Mustang GT Medium Canyon Red Factory Sunroof 32,000 miles - Sold to the right person (2013 - 2016)

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