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Ground gremlin?

Discussion in '308/328' started by duners, Oct 5, 2023.

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  1. duners

    duners Karting

    Aug 16, 2022
    134
    Los Angeles
    Full Name:
    Steven Carlson
    #1 duners, Oct 5, 2023
    I have noticed sometimes both slow down lights and fasten seat belts illuminates with key on. However, most of the time only the right slow down illuminates. Not sure if potential ground issue or normal.
    Also, in my rooting around came across the recess feature under t he dash near clock. See attached pic - Anyone know what this is for?


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  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,876
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #2 Steve Magnusson, Oct 5, 2023
    Last edited: Oct 5, 2023
    No, it's not "normal", but is most likely one of the slowdown light ECUs getting flaky (very common problem). You can swap the two slowdown ECUs to see if the problem moves to the other light/side (= bad ECU) or stays on the same side (which would be something else, but that's very rare). The slowdown ECUs are located behind the passenger (RH) footrest panel.

    The little socket is the +12V (and ground) power socket for the inspection light.

    Both of these issues/items are described in your 150/78 OM -- you have reading to do ;).
     
  3. duners

    duners Karting

    Aug 16, 2022
    134
    Los Angeles
    Full Name:
    Steven Carlson
    #3 duners, Oct 5, 2023
    As always much appreciated Steve. Any idea why the fasten seatbelt illuminates sometimes?
    Also, noticed a few times with key on fuel pump was not priming. Then after a couple on- off cycles of key it started working. This has only manifested recently.
    I do have birdman fuse block and will try swapping the ecus.
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,876
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #4 Steve Magnusson, Oct 6, 2023
    That also has its own specialized dedicated ECU -- see item 121 on your OM schematic. My guess would be it is just flaky, too, but that system also has a buzzer so if you don't hear that when the light is "on" = it's probably been unplugged. (PS On your OM schematic, the switch in the Driver's seatbelt is mislabeled as another "90" and should be something like "131".)

    Having the Birdman fuseblock is good. On your US model, there is also a "safety" switch built into the Driver's seat bottom that only allows the fuel pump to run when a Driver is sitting in the seat -- so keep this in mind (i.e., if you are not sitting in the Driver's seat = the fuel pump will not run with the key "on"). This seat safety switch is also fairly unreliable so often best to just connect the two wires under the Driver's seat together to always (and reliably) indicate a closed safety switch. If your safety switch has already been bypassed, yet you still have intermittent fuel pump operation with key "on" = not a good sign for the fuel pump itself.

    PPS Very much like the information that you have in your Profile -- don't delete it, but do please add to it if/when the status has changed (like it's now running! ;)).
     
  5. duners

    duners Karting

    Aug 16, 2022
    134
    Los Angeles
    Full Name:
    Steven Carlson
    #5 duners, Oct 6, 2023
    I did verify the driver seat switch is disconnected and seems to have a shorting
    Plug. When I hopped in driver seat tonight and turned key to on - no fuel pump sound. I cycled the key a couple times and then it started priming.
    I did have issues with window switches. Cleaned up driver side and got them working - not sure if I did anything.

    I did get it running but it’s def not running well. I have been putting off pulling the cam cover to verify forward bank timing hasn’t slipped. 1-4 bank timing is spot on.
    It will stall at low idle and running at 1200 rpm has lots of popping. Dist timing verified for both banks and carbs are close to balanced. I will create another thread for the popping and include video.
     
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,876
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #6 Steve Magnusson, Oct 7, 2023
    One observation that you can make here is -- do the gauges come to life and the alternator light illuminate with key "on" (engine not running) when no fuel pump sound?

    If no = bad sign for ignition switch (or upstream wiring/connections)

    If yes = bad sign fuel pump (or its wiring/connections)
     
  7. duners

    duners Karting

    Aug 16, 2022
    134
    Los Angeles
    Full Name:
    Steven Carlson
    #7 duners, Oct 7, 2023
    I tried headlights and the left was dancing. I swapp d the relays and problem went away. I thought why not pull all relays and put back in. Well it seems that was my gremlin. All dash lights with key on now work along with door dome light. These small moments success keep me persevering. Thanks for the help Steve.
     
    Sergio Tavares likes this.
  8. Sergio Tavares

    Sergio Tavares Formula 3

    Nov 15, 2018
    1,308
    Full Name:
    Sergio Tavares
    #8 Sergio Tavares, Oct 8, 2023
    Corrosion at connectione
     
  9. duners

    duners Karting

    Aug 16, 2022
    134
    Los Angeles
    Full Name:
    Steven Carlson
    #9 duners, Oct 8, 2023
    Yeah, I imagine they haven't been pulled in over 40 years and car has sat for last 10.

    Seems like all is working except the turn signals / hazard switch and fan switch. Now need to pull the console cover and see what surprises lurk beneath.
     
  10. bl10

    bl10 Formula Junior

    Jun 8, 2011
    442
    Chatsworth, CA
    Full Name:
    Barry Leavengood
    #10 bl10, Oct 8, 2023
    After sitting over two decades my 78 US had all kinds of electrical problems, hazard switch and turn indicators included.
    I did following and now everything works except the high beam flashers.
    1. Pull and clean all fuses and sockets.
    2. Reseat all relays.
    3. Spray contact cleaner in all switches ,including turn indicator stalk , then work switches back an forth.
    4. Soldered all contacts on stock fuse blocks. (the rivets get loose)
    5. Cleaned window cable mechanism (waste of time) so installed relays for windows to speed them up.
    5. Installed Classic Air ac as stock on just wouldn't keep up. (not electrical but great mod)
    6. Changed to LED bulbs all around except dash warning lights. (LED's don't have enough load)
    7. Installed Pertronix ignition and coils, Accel plug wires and Iridium plugs.
    8. Changed to modern 12 inch colling fans.
    9.Installed 185 degree cooling fan switch.

    The culprit in a lot of cases is the hazard switch as most circuits run through it.

    You'll find Paul's wiring diagrams invaluable for electrical work.

    Head light continuing to cycle can be cause by a bad diode (I think) in the head light motor.

    Good Luck
    Barry
     

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