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Slow Down Light Query

Discussion in '308/328' started by wda24729, Jul 23, 2015.

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  1. wda24729

    wda24729 Formula 3

    Sep 22, 2014
    1,000
    Devon, UK
    Full Name:
    Graham
    #1 wda24729, Jul 23, 2015
    Hi - Sorry for all the newbie questions but the 308 is fairly new to me and still sorting a few gremlins!

    Car is a 1980 GTSi 2V.

    When I turn on the ignition, the 1-4 light illuminates but the 5-8 doesn't.

    Ive checked the bulbs and these are ok

    With a test meter Ive noticed 1-4 have 12v to each of the cables on the back of the light however on the 5-8, only one of the wires has 12v, the other nothing.

    Can anyone help as to where I should be looking to rectify this?

    Thanks
     
  2. jmaz

    jmaz Formula Junior

    Jun 27, 2011
    350
    Colorado
    Full Name:
    Jim
    #2 jmaz, Jul 29, 2015
    Have you made any further progress with diagnosing this? I'm familiar with the 328's slow-down light operation and the ECU that drives it, but not with the 308's. Assuming the functions and the ECU is similar (which I think they are), then the ECU(s) circuit should complete the ground to the slow-down light for a few seconds after turning on the ignition. If you ground the 5-8 slow-down light, does it illuminate?
     
  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,932
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #3 Steve Magnusson, Jul 29, 2015
    Last edited: Jul 29, 2015
    One fairly easy thing that you can do is just swap the two warning light ECUs that are mounted behind the passenger footwell panel:

    If the same side fails the self-test = then you have something unusual wrong somewhere

    If the self-test failure moves to the other light = then you have the more common failure of a bad warning light ECU
     
  4. wda24729

    wda24729 Formula 3

    Sep 22, 2014
    1,000
    Devon, UK
    Full Name:
    Graham
    #4 wda24729, Jul 31, 2015
    Hi - Thanks for the replies. I did a bit more digging and found the control unit in the fottwell disconnected to Banks 5-8. I reconnected it and the light illuminates permanently. Thats as far as I got!
     
  5. jmaz

    jmaz Formula Junior

    Jun 27, 2011
    350
    Colorado
    Full Name:
    Jim
    #5 jmaz, Jul 31, 2015
    Perhaps next, just check and clean the connectors that attach to the control unit from the catalytic converter's thermocouple. If I remember right, at one point when my control unit was working intermittently and I was trying to de-bug it, I think that disconnecting the thermocouple connector(s) caused the slow-down light to stay on continuously. (My ECU's totally failed now though. I'm using a circuit I built as a temporary replacement for the ECU.)

    If checking the connectors doesn't help, then swapping the ECUs as suggested should tell you if you have a problem with the control unit itself, or perhaps a broken thermocouple lead.
     

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