[Mgs] Was: coil; now wiring issues

[Max Heim]

The wiring diagram shows an LG/U wire from the switch to the RH indicator, and LG/Y to the LH indicator. When connected this way, the RH indicator flashes when the switch is left, and vice versa. Looking at the naked switch, these wires are clearly originating on the “wrong side” — the LG/Y is on the same side of the unit as the G/W which leads to the RH lamps, so it can’t possibly operate the LH indicator, and so forth.

But I can’t determine if the mistake is in the part or in the labels in the diagram, since all one has to do is unplug the lamp and move it to the opposite socket in order to make the colors match up. This part is at least 15 years old so it is not eligible for returns. I don't know why I didn’t notice the discrepancy when I installed it in the old car. Possibly I assumed I had the lamps installed incorrectly and just swapped them without checking colors.

The flasher works — when the switch is left the indicator and both lamps function correctly. When the switch is right, the indicator flashes but the lamps do not. Bulbs are confirmed good. Presumably the grounds at the lamp units are good because the taillights and running lights work.

I was saying it had to be a fault in the switch because I can’t find any voltage anywhere on the G/W wire, not even where it exits the switch — on the back side of the rivet that is the contact point. This is despite the fact that it is located adjacent to the contact for the LG/Y to the indicator, which works, and is supposed to be switched simultaneously. I have been checking this with a test lamp as my digital multimeter will not show any reading on the flasher circuit.

It occurs to me that if I jumpered the two contacts with some solder on the wire-exit side, they would “have” to function simultaneously. This could be a possible solution. I can’t think of any reason why they would need to be independent (but then, why were they built that way in the first place?).

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Max Heim
'66 MGB

> On Jul 30, 2018, at 3:17 AM, PaulHunt73 <paulhunt73 at virginmedia.com <mailto:paulhunt73 at virginmedia.com>> wrote:
> 
> Not sure exactly what you are saying is incorrect - if the colours don't match up between the new and old switches, or the new switch and your harness, or if the wrong side flashes.  Colours on replacement switches can be wrong.  If Moss have supplied an incorrect item then return it, or at least talk to then about it.  You shouldn't have to modify your car to get their stuff to work correctly.
>  
> I'm also not exactly sure what is happening, or not happening.  You seem to be saying the indicator flasher clicks, but the lamps aren't lighting?  In that case you have an incorrect indicator flasher unit. As a 66 you should have the original large cylindrical 3-pin flasher.  That shouldn't click unless it is powering at least one bulb, and if only one bulb is working it should only give a very brief flicker.
>  
> If one side is OK the flasher unit is OK, so start at the switch.  And given your concern about wiring colours, having individual bullets it may not have been connected correctly.
>  
> With 12v on the pump terminal (if right on the spade) and not on the pump body then it almost certainly is the points oxidised.  Remove the cap, separate the points carefully and slide a piece of fine wet and dry through them, both sides.
>  
> PaulH.
>  
>  
> ----- Original Message -----
>> 
>> I wasn’t pointing fingers, just reporting a fact for general reference. I found another discrepancy today, although it is unclear whether the fault is in the wiring diagram or the part. The colors shown for the turn signal indicator wires are reversed, compared to the wires built into the turn signal switch. This was a Moss replacement switch, made in China, so it is very likely that it was just manufactured incorrectly. Anyway, it is easy enough to just switch the lamp positions.
>> 
>> I am having a persistent problem with the right side lamps, however. The indicator flashes, but I can’t get anything out of the front or rear lamps.  I can’t even get the test lamp to flash with the probe inserted in the very first junction, or even on the contact in the switch itself. This is rather baffling — all it could be is a discontinuity inside the copper rivet, it seems to me. This switch was functioning on the other car, last year, but I can’t say I am very impressed with its quality of construction. Unless someone has a better suggestion, I think I am going to order another switch.
>> 
>> I still don’t have the fuel pump working. It has 12v at the terminal, and not on the body. I am thinking I will have to take it apart and look at the points. I got distracted with the dash wiring.



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Max Heim
mvheim at sonic.net



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