Which wire to stop 1st gear fault code (LET)
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Thread: Which wire to stop 1st gear fault code (LET)

  1. #1
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    Which wire to stop 1st gear fault code (LET)

    I heard that when fitting the LET to an astra you should cut one of the wires on the car to ECU wiring plug.

    Does anyone know what this wire does and what colour it is?

    I have fault code 42 come up every time I drive faster than about 40mph and it stays on until I reset the ECU.
    I have tested the 1t gear switch and found it to be OK.
    I have also tested the 1st gear switch wiring plug, 5 volts on one pin and GND on the other (as expected).

    In my opinion it must be something else and the only other thing I can think of is someone mentioning the wire you need to cut...

    marek

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    ok there are 3 gear selection plugs on the LET loom. one for 1st and the two other reverse. you need to bridge the 1st gear one with a bit of wire. as far as i know the plug is white with brown wire and brown/red wire.

    with the reverse one you need to fit the reverse plug from the LET loom to the gearbox then fit the nova reverse light plug onto the plug on the LET loom

    HTH

    rodgerq
    thick red - battery, thin black - igntion switched feed, thick red/blue - fuel pump, brown/blue - ecu light. thin green - rev counter.

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    so you have the 6sp box fitted then?

    Yeah make sure the reversing light wiring is connected upto the ecu loom.

    if it still fails cut the blue/red wire going into the ecu loom in the passenger footwell. (speed mph wire). or maybe the problem is because it's not connected in the first place ?!

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    Yeah, it's a LET and F28 fitted to a 97 Mk3 rag top.
    Don't remember there being a spare plug hanging around that area.
    They're there, in their room.

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    Can the reversing light switch cause this fault code as well then?
    I have noticed that the reversing lights do not work.

    How will cutting the speed wire affect the ECU?

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    Originally posted by Astra Dan
    Yeah, it's a LET and F28 fitted to a 97 Mk3 rag top.
    Don't remember there being a spare plug hanging around that area.
    the plug is actually back up the loom a bit. just on the outside(gearbox side) of the plastic box that holds the injector plugs.

    rodgerq
    thick red - battery, thin black - igntion switched feed, thick red/blue - fuel pump, brown/blue - ecu light. thin green - rev counter.

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    Fix the reversing lights and you have half a chance of fixing the problem.

    1) make sure the reversing lights work correctly
    2) make sure the ecu loom is connected up to the reversing lights.

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    As a quick fix what about grounding or letting an ECU pin float?
    They're there, in their room.

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    The only quick fix might be to cut the blue/red wire in the footwell.
    But as you have a 6spd box that's not recomended.

    It can't be that difficult to get the reversing lights working.

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    surely its as simple as pluggin in the plugs to where i have said. everythin should be ok then. was on my nova anyway.

    rodgerq
    thick red - battery, thin black - igntion switched feed, thick red/blue - fuel pump, brown/blue - ecu light. thin green - rev counter.

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    Everything is plugged in, and we've tested both the reverse and 1st gear switches and they're fine.

    Marek noticed there is a black sleeve with a white stripe that the 1st and reverse gear switches plug into, the one that's left with no sleeve is plugged into the one near the box that goes over the injectors.
    Now, we have black/white and black/yellow plugged into the uppermost gearbox plug (reverse?), and brown and brown/red plugged into the lower gearbox switch (1st gear?).

    Tried cutting the thin blue/ red wire by the ECU, and it appeared to mess up the immobiliser: the ECU light flashed quickly and the engine would turn over but not fire! The only red/blue wire left is the thick one for the fuel pump.


    HELP!!
    They're there, in their room.

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    well you dont really wanna be cuttin that one now do you

    in fact you shouldnt need to cut any wires if you are running the F28!!. the plugs should all fit into place. the only reason you would need to stop the first gear limit is if you were running an F20 which doesnt have the plug. if you wanna remove it even with the F28 box then just short out the wires of the plug goin to the 1st gear switch.

    it sounds like you have it done correctly! are you still gettin low boost now? have you tried readjusting the actuator?

    ill have another look at the looms i have here and see whats what. if i see any difference to what you have setup i will post up.

    rodgerq
    Last edited by rodgerq; 18-06-2003 at 18:12.
    thick red - battery, thin black - igntion switched feed, thick red/blue - fuel pump, brown/blue - ecu light. thin green - rev counter.

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    Oh didn't realise you had an imboliser


    Are the reversing lights working yet ?


    The ecu loom with white stripe should plug into the top of the gearbox.

    The connector on the ecu loom by the box above the injectors should plug into the cars engine loom. (black sleeve only)

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    Reverse lights still don't work, despite testing switch and bulbs.

    It has the standard transponder immobiliser, luckily the bloke selling the engine was clever enough to include the key and ignition switch!

    Get full boost untill you go over 40MPH, then the ECU light comes on and the boost is halved. It's fekkin quick till then!

    We have white sleeved stuff pluged into the box, two of them, one into the top, one into the bottom.

    The one that's not sleeved is plugged into the socket near the injectors.


    They're there, in their room.

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    Oh yeah.

    To avoid cutting the cars loom, we got a round engine bay plug from a scrappy and soldered it to the LET loom so it matched the car loom colour for colour.

    I noticed there's a brown (earth, right?) in the car side that's not connected to nowt on the engine side.

    Now, doesn't the reverse lights work on a switch on the negative side? So this may have an effect?
    They're there, in their room.

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    That brown is not meant to be connected so don't worry.


    Get them bloody reversing lights working.

    Try disconnect the ecu loom from the gearbox and plug the engine loom into the gearbox and see if they then work.
    That will help locate the fault.
    Last edited by Andy K; 18-06-2003 at 19:44.

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    OK, I suppose if we unplug the ECU bit form the reverse lights, and plug them straight in and they then work, this could point to a bad connection to the ECU?
    They're there, in their room.

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    yeah thats what to ttry. put the plug from the car loom that works the lights sttaight into the box and see if you get reverse lights. on my nova the plug from the ecu loom thats meant to go to the gearbox reverse switch is attached to the plug up at the injectors. i have no problems with this setup.

    rodgerq
    Last edited by rodgerq; 19-06-2003 at 00:40.
    thick red - battery, thin black - igntion switched feed, thick red/blue - fuel pump, brown/blue - ecu light. thin green - rev counter.

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    Cheers!
    I'm sure we'll be back!
    They're there, in their room.

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