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Warning Light indicating burned out bulb is malfunctioning on '81 Mondial 8

Discussion in 'Mondial' started by Plutexams, Apr 7, 2020.

  1. Plutexams

    Plutexams Rookie

    Mar 31, 2018
    16
    Full Name:
    RICHARD R PLUT
    The yellow general warning light and the warning light indicating a bulb is burned out comes on whenever I turn on the lights and the ignition. It does not come on until the ignition is on. I have discovered that the switch to operate the fog lights doesn't work but I can turn on the fog lights by bypassing the switch (shorting the contacts at the switch) but that doesn't affect the warning light. I will need this light to go off to pass inspection. All fuses are good and I am unable to find any light that is not on. Any help would be appreciated.
     
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  3. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
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    Brian Crall
    When did it come on?
     
  4. Plutexams

    Plutexams Rookie

    Mar 31, 2018
    16
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    RICHARD R PLUT
    I don't know exactly since I don't drive it much and usually during the day, but it wasn't a problem when I got the car about two years ago. I'd say it started in the Summer. I have checked all bulbs, including dash and license plate and can't find any that are out. Thanks much.
     
  5. Wade

    Wade Three Time F1 World Champ
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    Mar 31, 2006
    32,194
    East Central, FL
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    Wade O.
    More than just the lights. From the USA Mondial 8 Owner's Manual (1981):

    "A - Main yellow warning light will be activated by the failure of one or more items 6 trough 10."

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  6. Wade

    Wade Three Time F1 World Champ
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    Mar 31, 2006
    32,194
    East Central, FL
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    Wade O.
    Where are you located with such strict inspection requirements? Do you have an Owner's Manual to explain to the inspector about how the car works?
     
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  8. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
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    Brian Crall
    The reason I ask is I have seen warning lights come on when a different brand of bulb is used. They are not all that sensitive but can be. For that reason many shops stick to OSRAM brand. Also just socket corrosion can cause it. Socket corrosion is very common in the license plate light sockets. And the ground wire connections for it. It was a very problematic system and generated a lot of warranty claims.
     
  9. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
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    Brian Crall
    Doesn't matter. Some states have a catch all rule that any safety item, system or warning must be functional and indicating proper operation.
     
  10. Wade

    Wade Three Time F1 World Champ
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    Mar 31, 2006
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    Wade O.
    Yes, I can agree that a functional a/c system is critical for safety in Florida. ;) :)
     
  11. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
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    Brian Crall
    He specifically stated it has a bulb warning, not an A/C warning.
     
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  13. Wade

    Wade Three Time F1 World Champ
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    Mar 31, 2006
    32,194
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    True, he only mentioned the bulbs. I was asking if he was aware that other systems will also trigger the yellow warning light (e.g. low-level windshield washer fluid and "no freon").

    However, when I had the same problem it turned out to be the license plate light.
     
  14. Plutexams

    Plutexams Rookie

    Mar 31, 2018
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    RICHARD R PLUT
    I do know the general warning light comes on when there any of the items 6-10 come on and it is light 9 coming on that is the issue. I live in Pennsylvania and it is a requirement that there be no active warning lights to pass inspection. I have not taken out every light to look for corrosion but that probably should be my next move. I would have expected a light to be dim, or at least dimmer than it was if there were a corrosion issue and none of the head, tail, marker, dash, or license plate lights are dim. There has been a problem with the turn signal indicator not working and it is corrosion in the socket and cleaning solves the problem. I would rather disconnect the indicator since it is clearly problematic but will do the work and look at each socket and bulb. Thanks for the suggestions.
     
  15. Albert Penello

    Albert Penello Karting

    Jul 21, 2019
    162
    Woodinviille, WA
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    Albert J Penello, Jr.
    Just to be clear, if it the small yellow LED on #9 that's coming on?

    Do you have any LED's installed? Have you physically inspected every single light across the car?

    I'm having a similar problem - every single light on my car is actually working functionally, but that darn warning light still comes on.

    Check for areas where you see a slightly dim light as well as that could indicate bad ground somewhere.
     
  16. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    2,601
    Just unplug the check control when you go in for safety.

    Interior switches that don't work or are intermittent just need a little WD-40. I would also clean the connectors on the fuse box.

    Light bulbs are cheap. You might want to just replace all the running lights.
     
  17. greatscott73

    greatscott73 Karting

    Sep 1, 2017
    233
    West central Florida
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    Howard Scott
    #14 greatscott73, Apr 9, 2020
    Last edited: Apr 9, 2020
    I had the same problem with mine awhile back, and it turned out to be a burned out filament on the tail lamp portion of one of the two-filament brake light/tail lamp bulbs. Since each stop/tail lamp housing contains two bulbs, at first glance it appeared like the light was still operating when I would turn the lights on and then glance at the rear of the car. Turns out, the top half of the lens was illuminated, but not the lower half, which I didn't notice at first. I finally walked about ten feet behind the car and it became obvious the lower half of the lens was dark. Once I put a new bulb in, the problem went away. Check both filaments on all four bulbs. This is on a 1987, but I suspect it is similar, if not identical, to yours. Hope it helps!
     
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  18. Wade

    Wade Three Time F1 World Champ
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    Mar 31, 2006
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    Great point. Here's from the 1981 Mondial 8 Owners Manual. Notice the three bulb receptacles (retainers).

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  19. Plutexams

    Plutexams Rookie

    Mar 31, 2018
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    RICHARD R PLUT
    I have gone through all the bulbs, checked for corrosion and cleaned several, checked all with an ohmmeter. I thought I had it when I found a bad ground, replaced the corroded spade connector, the warning lights are still on and all lights on the car work. I am at a loss as to how to proceed. Any way to disconnect the warning light? With all lights working I can't help but think the problem is the warning system itself.
     
  20. Albert Penello

    Albert Penello Karting

    Jul 21, 2019
    162
    Woodinviille, WA
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    Albert J Penello, Jr.
    Do you have any LED bulbs? What about your dashboard lights? Someone suggested that the light controller is also looking at instrument cluster lights but I'm not 100% sure.

    I'm having the same problem as you (I do have LED's in my dash however) so I'm super curious about the solution.
     
  21. Plutexams

    Plutexams Rookie

    Mar 31, 2018
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    RICHARD R PLUT
    No LEDs in my car. I can see how they might cause this problem since they draw less current. I have checked and cleaned the dash light too and they are all working. I am at a loss.
     
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  22. Wade

    Wade Three Time F1 World Champ
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    Mar 31, 2006
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    Attached is Section I of the Workshop Manual (first page through I 12) which covers the Check Control and the bulb specs. It also states "front" lights which may include the fogs. If that's the case, why not replace the bad switch and then continue your troubleshooting?

    There's also a reference to an...

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    Have you looked at that as well?
     

    Attached Files:

  23. Wade

    Wade Three Time F1 World Champ
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    Mar 31, 2006
    32,194
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    Wade O.
    Btw, where are you located?
     
  24. Albert Penello

    Albert Penello Karting

    Jul 21, 2019
    162
    Woodinviille, WA
    Full Name:
    Albert J Penello, Jr.
    I'm not the OP but offering this in case it helps. I went out again tonight and BOOM problem solved. Turns out based on reading the workshop manual I could eliminate the dash lights (good news you can have LED's!). So I went to the garage, opened the trunk, put the car in reverse and turned the car on and turned on EVERY light including fogs). I discovered two issues I had missed previously.

    1. One of my marker lights was a bit dim. At first I assumed it was a bad ground but I replaced the bulb and in fact it was a bad bulb.
    2. A License plate light was intermittent. It would be on, then I would turn on-and-off the lights and it went out.

    So fixing both of these issues and my check control light went out. So to the OP I would suggest maybe going out with a battery charger and turn on all your lights and really do a walk-around.

    FWIW there are also 2 bulbs in each tail light so you may want to double check they are both good.

    Good luck!
     
  25. Plutexams

    Plutexams Rookie

    Mar 31, 2018
    16
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    RICHARD R PLUT
    Thanks all. Response to some of the posts, I have a shop manual including the section referenced in the link. The reasons to not simply replace the switch for the fog lights are multiple. One, it is no longer available. It is not a switch but a relay. The coil sections are all connected in parallel with short jumpers. I have checked for voltage at all the switches. The fog lamp switch has power going to it and when I bypass the relay and supply power to the fog lights they go on and the warning light does not go off. The current state of the fog lamps is that they are functional but are not turned on by the switch, which should not send a fault. I have spent several hours going through each lamp, measuring continuity, checking the grounds, cleaning corrosion where I found it. I am willing to admit there is something I am missing but at this point, don't know were to find that something. I appreciate the suggestions.
     
  26. Wade

    Wade Three Time F1 World Champ
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    Mar 31, 2006
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    #23 Wade, Apr 16, 2020
    Last edited: Apr 16, 2020
  27. Wade

    Wade Three Time F1 World Champ
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    Mar 31, 2006
    32,194
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    Wade O.
    Italian Car Parts website shows a used one available. It's been a long time since I've compared the two versions so it's best to verify...

    Fog light switch, Testarossa, good used: #fr121607u $197.50 ea

    http://www.italiancarparts.com/parts/512TR.html
     

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