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  1. #1
    Join Date
    Feb 2006
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    Somerset
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    1,076

    Wiring mix up....?

    Hi.
    My car has been off the road for a while (Sorn'd) due to house move, extensions etc etc. Prior to all that I put a new engine in (347 Ford) and a Tremec TKO600 gearbox. I never got the speedo working right (ETB Electronic) and as I am now in a position to spend some time on the car again I need to sort it. Having read a lot on the internet, I feel I may have got my electronic speedometer pick-up\sensor and reverse light pickup\sensor mixed up. Can anyone confirm to me which is the Speedo pickup (I am using the one on the passenger side of the gear box) and which is the reverse light pickup (I am using one on the drivers side of the gearbox). What I don't understand is if I am wrong, the reverse light works fine even if it is on the wrong pickup but the speedo doesn't.

    Help please.

    Martin

    GD427 Mk4. Chassis No J0258

    Ford 347ci Stroker - AFR 185 heads - Holley 670 - KB Pistons - Lunati "Voodoo" 272/280 Cam - 451 bhp/441 lbft.

  2. #2
    Join Date
    Dec 2008
    Location
    West Sussex
    Age
    61
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    195
    On my tko 500 the wiring harness on the driver side main gearbox housing is the speedo the passenger side is the reverse switch. I did buy the correct wiring harnesses from the States.
    Last edited by AKBaz; 24-04-17 at 01:57 PM. Reason: Added info

  3. #3
    Join Date
    Jun 2003
    Location
    Brackley, Northants, England.
    Posts
    821
    If your reversing light is working correctly then it must be connected to the right place on the Gearbox.

    An easy way to check the speed sensor and wiring is to disconnect the input wires at the speedo and measure the Gearbox speedo sensor resistance it should be around 1,000 ohms. My TKO600 sensor measures 1,040 ohms. If it's zero or open you have a problem.

    If you do search here you'll find an article I wrote on Speedo problems which I think was also repeated in a Snake Torque.

    Denis

  4. #4
    Join Date
    Feb 2006
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    Somerset
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    Hi Denis

    I have attached two pics from the Internet. Pic 1 is where I have the reverse light wire connected to(or Backup light as the Americans call it), and Pic 2 is where I have the speedo sensor wiring connected (the two pronged connection on the side of the box). The problem for me is that on both of these pictures the internet caption disagrees with the way I have done it, i.e. Pic 1 according to the internet is for the Speedo and pic 2 for the Reverse light....!! Could the reverse light work off the wrong port? is it just an on off switch? Does the wiring for your TKO agree with me from what you can see?

    Thanks

    Martin
    Attached Images Attached Images

    GD427 Mk4. Chassis No J0258

    Ford 347ci Stroker - AFR 185 heads - Holley 670 - KB Pistons - Lunati "Voodoo" 272/280 Cam - 451 bhp/441 lbft.

  5. #5
    Join Date
    Dec 2008
    Location
    West Sussex
    Age
    61
    Posts
    195
    Martin the brass two pronged connection on the left side of the box is 100% definitely the reverse light connection. How or why your reverse light works if wired to the speedo side is unknown to me. If you get the correct harnesses and wire it correctly it will all work perfectly first time as mine did.

    Barry
    Last edited by AKBaz; 24-04-17 at 06:30 PM. Reason: Wording

  6. #6
    Join Date
    Feb 2006
    Location
    Somerset
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    Quote Originally Posted by AKBaz View Post
    Martin the brass two pronged connection on the left side of the box is 100% definitely the reverse light connection. How or why your reverse light works if wired to the speedo side is unknown to me. If you get the correct harnesses and wire it correctly it will all work perfectly first time as mine did.

    Barry
    Hi Barry

    Thanks for the confirmation. I guess my next step is to get underneath and swap the wires over, reverse light first. If that still works then I am making progress!!!

    Martin

    GD427 Mk4. Chassis No J0258

    Ford 347ci Stroker - AFR 185 heads - Holley 670 - KB Pistons - Lunati "Voodoo" 272/280 Cam - 451 bhp/441 lbft.

  7. #7
    Join Date
    Apr 2005
    Location
    Worcestershire
    Age
    44
    Posts
    2,175
    My TKO500 also has a two pronged output for neutral, to stop you cranking the engine while in gear. I think it was on the passenger side if I remember correctly?

    I've used a magnetic sensor on the prop shaft for my speedo.

  8. #8
    Join Date
    Jul 2008
    Location
    Lanarkshire Scotland
    Age
    58
    Posts
    51
    Hi,
    Iv'e been reading this with interest and sorry to go off in a slight tangent but is it better to connect the speedo to the Tremec gearbox or to the magnetic sensor on the prop shaft.

    Terry

  9. #9
    Join Date
    Dec 2008
    Location
    West Sussex
    Age
    61
    Posts
    195
    Terry if you have a programmable speedo like the Smiths type that i have, then just get the correct harness, connect to the speedo, calibrate and forget.
    Last edited by AKBaz; 24-04-17 at 09:06 PM. Reason: Wording

  10. #10
    Join Date
    Jun 2003
    Location
    Brackley, Northants, England.
    Posts
    821
    Martin

    I can't see your pictures on this small tablet of mine

    If the Reverse light is working using a connector on the TKO600 then it is connected to the RIGHT place.

    The reversing switch is just that, an on/off switch operated when you select Reverse.

    The Speedo sensor is effectively a small alternator coupled to the Gearbox output shaft. The two connectors are NOT interchangeable.

    The reversing light will NOT work if you connect it to the speedo sensor as the lamp will have the 1000 ohm resistance of the sensor in series with it and in any case it's not affected by selecting reverse or any other gear.

    Denis

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