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Blinkers inconsistent working

Discussion in '365 GT4 2+2/400/412' started by SouthJersey400i, May 7, 2022.

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  1. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,668
    Romulus, NY (Finger Lakes)
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    Ken Battle
    #1 SouthJersey400i, May 7, 2022
    My blinkers work occasionally but more often not. The hazard lights always work (key on or off). When left blinker does not work the right one does not either, and vice versa. I have spent some time with speedo removed and left sun-glass holder out. Sometimes some wire giggling got blinkers to work for a short time. Sometimes turning on hazard lights on for a few seconds and then going to blinkers, and again blinkers would work a short time. My best guess is a loose ground: both blinker switches and flasher unit go to the same ground. See wiring diagram below. Anyone know the exact location of the ground point I have circled in red. Other thoughts welcomed too.
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    I'm leaving for a 1000 mile rally in a few days, so I am in a bit of panic! I'll be working on my hand signals, but likely <10% of people on road know what they mean!
    Ken
     
  2. samsaprunoff

    samsaprunoff F1 Rookie
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    Sam Saprunoff
    #2 samsaprunoff, May 7, 2022
    Good day Ken,

    I suspect the ground point is the frame member behind the speedo/tach gauges. I say this, as on my 365 this is where the main ground is. On the 365 it is the voltage regulator mounting stud... which is behind the speedo.

    Just to rule out any stalk/signal contact issues, I would remove the steering wheel/hub to gain access to the signal stalk contacts, as over time these oxidize and make intermittent connection resulting in the symptoms you described. This occurred last Summer in my Boxer and once I cleaned up these connections with some very fine sand paper,etc my signal lights worked perfectly. If you have the tools then accessing this area, etc is quick and easy and the overall time to do this is maybe 20-30 mins.

    Cheers,

    Sam
     
  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    #3 Steve Magnusson, May 7, 2022
    Last edited: May 7, 2022
    The hazard lights working really doesn't have much to do with the turn signals (except confirms the flasher is OK, and confirms the ground connection you circled is OK). The hazard light switch is really two double-throw switches inside:

    When "off", switch mechanism #1 inside it connects a key-controlled +12V source (the VB wire on terminal 5) to the M wire on terminal 6 that goes to the flasher. The flasher then internally connects the M wire to the BN wire that goes to the turn signal switch pole, and, if the turn signal switch pole (wire BN) is connected to left or right (A or AN) then those turn signals flash. Switch mechanism #2 doesn't do much in the "off" position.

    When "on", switch mechanism #1 uses a different set of contacts to connect an always +12V source (the RG wire on terminal 4) to the M wire on terminal 6 that goes to the flasher. Switch mechanism #2 connects the BN wire to both the A and AN wires (acting like a turn signal switch connected to left and right at the same time) = all the turn signal lights flash.

    Sam certainly has a valid point that the switch contacts in the turn signal switch itself could not be making good contact - so that's still on the possible list, but there are two other possibilities:

    1. No +12V on the VB (green-white) wire at the hazard switch when the key is "on". One way to check this is this VB wire also supplies +12V to the reverse lights. If the reverse lights also are not working = strong sign that you have an upstream problem causing no +12V on this VB wire. And, conversely, if your reverse lights work = the VB wire OK.

    2 When the hazard light switch is "off", it is not correctly connecting the VB (green-white) wire to the M (brown) wire. You can manually connect the VB wire to the M wire at the hazard light switch. If the turn signals then work (key "on") = something bad with the hazard light switch mechanism #1 contacts = buy a new hazard switch or repair it.

    3. If not #1 or #2 = then justifies going after Sam's suggestion.

    Good Hunting!
     
  4. SouthJersey400i

    SouthJersey400i Formula 3

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    Ken Battle
    #4 SouthJersey400i, May 8, 2022
    Steve
    Lots of good stuff there. I was wondering how the power got to the blinker switch; there did not seem to be a 12+ supply, but coming from Hazard switch is the reason. That now seems my most likely issue, since no power would affect both blinkers and the stalk switch should be one at a time.
    Note: my stalk switch was rebuilt last winter and driven a lot of miles since. Hazard switch was replace 3-4 years ago after the usual problem of not locking in off position.
    I'm gonna print out you text and get the volt meter and alligator clips out. First check will be the reverse light.
    Ken
     
  5. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
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    Ken Battle
    #5 SouthJersey400i, May 8, 2022
    Small update: Went for the same short drive as last two days and of course the blinkers worked about 80% of time and of course, it won't fail sitting in the garage where I can do some tests! But I did have one short instance the blinkers were not working; I put trans in reverse to check the lights and the blinker started working! This was a one time event but Reverse switch may be the link to a solution. Going out for Mother's Day brunch now and if my stomach does not burst I will be back at it this afternoon.
    Ken
     
  6. theunissenguido

    theunissenguido F1 Rookie
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    #6 theunissenguido, May 8, 2022
    When you have a moment that blinkers are'nt working, try once moving the bulb itself...sometimes 1 bulb have bad contact and the other bulb want work also...
     
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  7. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,668
    Romulus, NY (Finger Lakes)
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    Ken Battle
    #7 SouthJersey400i, May 8, 2022
    Steve's note was really helpful giving hope to a solution.
    Okay, I spent about 2 hours tearing into the system. Speedo and Tach out and hazard switch eventually out. One issue is the blinker wanted to work most of the time rather then failing so I could see what was wrong.
    First, with The two big gauges out I could not find a grounding lug. All of the black wires disappeared into wire harnesses and seemed to continue to the right and head behind the AC evaporator.
    When the blinker finally failed: a) the Reverse light was working (so VB wire is okay), b) there was no power to the BN wire to the plug going to the stalk switch. So the later seems to be the problem.
    I would have never thought the hazard light switch had multiple functions!
    When the blinker was in a working state I did a series of wire tests at the hazard switch:
    Key off - only power was to the red wires.
    Key off and hazard switch on, this added power to the M wire, only.
    Key on and Hazard off: M, VB and BN wire had 12 V
    -Turning left or right blinker on gave power to the A or AN wires on the stalk plug
    I believe all of this is the normal function for the hazard switch and wiring.
    When in the blinker failure mode with the key off, I tired a jumper from the VB wire to the BN wire. With L or R blinker on the lights came on but did not blink. I had the same result with jumper wire from the red wire to the BN wire with the same result. Clearly this was because there was no power on the M wire to the flasher unit. Looks like I needed to do one more test.
    End result. I put everything back together and blinker appears to be working consistently again! It sounds like some connection was loose and is not back together. Optimistic, probably!

    Based on Steve's notes, it could be a dodgy hazard light switch, so I set out to order a spare. I previous bought one from "International Auto Parts" who dealt in Alfa and Fiat parts. They were bought by Centerline who had a switch listed for same year cars that had a different prong configuration than the one bought in 2011 (which was identical to our originals). Another site sole that same switch with short wires with double female connectors on each wire so one could fit it to the original plug. Visually it is a bit different as well.
    https://centerlinealfa.com/catalog/hazard-switch-1971-81
    Anyone know a source of the original switches? It had a Part#34358000.
    Ken
     

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