Author [NL] [FR] [ES] [DE] [SE] [IT] Headlights not working  (Read 1745 times)

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  • Offline burnsr

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    Offline burnsr

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    Headlights not working
    on: Feb 05, 2019, 12.54 pm
    Feb 05, 2019, 12.54 pm
    HI all

    Recently the headlights stopped working on my 2012 TTSE, I was a bit confused at first as there is 12v at the coil of the headlight relay but it does not operate, upon further investigation I realised the negative earth that comes via pin A18 of the ECU has a resistance of 40KΩ! Not good.

    My problem is that the service manual has very little information regarding the ECU, in particular how the pins are numbered or even which plug is A and which is B. I would appreciate any help as to how I could be getting a bad earth from the ECU or how pins are numbered or if I may be barking up the wrong tree completely. And why does the earth come via the ECU is it some kind of monitoring system?

    Thanks for your help

  • Offline Coconut   gb

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    Offline Coconut

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    Re: Headlights not working
    Reply #1 on: Feb 05, 2019, 02.31 pm
    Feb 05, 2019, 02.31 pm
    Hi burnsr,

    There is some information in the Service Manual,
    but not necessarily where you might expect to find it !

    The ECM has two connectors - one has 36 Pins, and the other has 48 Pins :



    Section 10, ( File System / Engine Management ) Page 26, of the Service Manual has this image :



    ( Note that the Service Manual goes on to WRONGLY describe Connector A
    as being the Larger of the two !  :087: )

    Section 10 Page 131 discusses accessing and removal of the ECM.

    With regards Testing of the ECM Pins - be VERY careful !
    You don't want to accidentally apply Power to a Pin that shouldn't be connected to Power.
    A new ECM to replace a "fried" one will be VERY Costly !
    Other than checking the two plugs are firmly connected to the ECM
    it's probably best to make checks at the peripheral equipment ( Relays & Switches etc ).

    Earth or Ground switching within an ECM is not unusual .


    One of the first things to check is for any Diagnostic Trouble Codes ( DTC's )
    that might give a clue as to what the problem is.

    See this Topic : Servicing Data, Reference Info. & DTC ( Fault ) Codes - Scroll down to Reply #8. 
    At the end of the Post is a document that can be download explaining
    the meaning of any DTC's that are found, and other information.

    Worth noting : Ordinarily the Headlight only comes on while the Engine is running.  :164:
    They CAN be switched on without starting the engine, by holding the Clutch lever IN
    while switching the Ignition to the ON Position.

    Assuming both Headlight Bulbs are good ( I know ! ), the next thing I would check
    is the Ignition Switch wiring - there have been previous reports of tight / misrouted wiring
    that emerges from the bottom left of the Ignition switch, becoming strained when the handlebars
    are turned full lock to the right, resulting in wires being severed or pulled out.
    The red wire with Blue stripe from the Ignition switch feeds the Headlight Relay.

    With the engine running, turn the handlebars from lock to lock a few times,
    and any problems in that area may show up.

    There is a Topic here about this problem : Ignition Switch Wiring Failures

    If all is well with the Bulbs and the Ignition Switch wiring, move on the Headlight Relay. ( No.4 ) :



    Pin 3 of the Headlight Relay ( Purple ) should be at 12v
    supplied by Fuse No.1 from the rear Fusebox.

    When the Headlight Relay is energised Pin 3 connects to Pin 5 ( Blue )
    which feeds to the Headlight Switch on the left Handlebar.

    Power to energise the Headlight Relay is provided by a 12v supply from the Ignition Switch
    ( Red wire with Blue stripe ) when the Ignition is switched ON.

    The Negative side of the relay Coil is via the Black wire with Brown stripe,
    that connects to Pin A18 of the Main ECM.

    If the Output from the Headlight Relay Pin 5 ( Blue Wire ) is good,
    the next point in the Circuit is the Handlebar Switch connector block.
    I "believe" this is located under the left side of the Fuel Tank.

    The connections can be checked at the Headlamp bulb connectors without removing the Fuel Tank :
    The Blue wires with Red stripe are for the Dipped Beam,
    and the Blue wires with White stripe are for the Main Beam.

    If there's no Power at the Headlamp bulb connectors, and you have confirmed Output
    from the Relay, then the fault must lie, probably in the connector under the Tank,
    or in the Handlebar switch, or somewhere along the length of the wire(s).

    Hope some of this helps - let us know how you get on !  :169:

    Cheers  :821:







    Last Edit: Jan 26, 2020, 04.50 pm by Coconut

  • Offline burnsr

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    Offline burnsr

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    Re: Headlights not working
    Reply #2 on: Feb 05, 2019, 05.22 pm
    Feb 05, 2019, 05.22 pm
    Wow, that's a lot of information, thanks coconut.

    Now I know where I am going with those ECM connectors, hopefully I will get time tomorrow to do some more careful testing.

    Thanks again.

  • Offline Coconut   gb

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    Offline Coconut

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    Re: Headlights not working
    Reply #3 on: Feb 05, 2019, 05.44 pm
    Feb 05, 2019, 05.44 pm
    My pleasure !  :028:

    Last Edit: Jan 26, 2020, 04.49 pm by Coconut

  • Offline burnsr

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    Offline burnsr

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    Re: Headlights not working
    Reply #4 on: Feb 06, 2019, 06.31 pm
    Feb 06, 2019, 06.31 pm
    FIXED IT   :152:

    It was the classic modern technology stand by, "turn it off and turn it back on again".

    A friend suggested disconnecting the battery for ten minutes, reconnecting and try again, I did that and now headlights are working.

    I am obviously really pleased that its now working again but the amount of time I wasted searching for a phantom fault. :087:

  • Offline Coconut   gb

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    Offline Coconut

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    Re: Headlights not working
    Reply #5 on: Feb 06, 2019, 08.12 pm
    Feb 06, 2019, 08.12 pm
    Glad to hear you got it working again, but how strange !

    Did you check for any DTC's as suggested ?



    Last Edit: Jan 26, 2020, 04.48 pm by Coconut

  • Offline earthman   gb

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    Re: Headlights not working
    Reply #6 on: Feb 06, 2019, 08.13 pm
    Feb 06, 2019, 08.13 pm
    *Originally Posted by burnsr [+]
    FIXED IT   :152:

    It was the classic modern technology stand by, "turn it off and turn it back on again".

    A friend suggested disconnecting the battery for ten minutes, reconnecting and try again, I did that and now headlights are working.

    I am obviously really pleased that its now working again but the amount of time I wasted searching for a phantom fault. :087:

    That's good to hear, fingers crossed that it doesn't happen again.

    This is what I hate about modern vehicles, ECU's being involved in even the simpler but crucial items. :012: