# Turn Signal Indicator not working in 1965 GTO



## Toucan49 (May 1, 2020)

Help needed, I have a new M and H dash harness, the socket for the turn signal indicator is plastic and has hot feed from the bottom and a upper side, I have power at both hot feeds in the socket but bulb will not light, it appears the socket is plastic and how is it suppose to be grounded. Why can't repo parts work? Thanks


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## GTO44 (Apr 11, 2016)

It should only have power at the very bottom. The upper portion should be in contact with the body/housing of the light bulb which is ground. It wouldnt be hard to cut the wire coming from the upper portion and splice a length of wire onto it and attach it to a ground.

on a side note, make sure you have all the grounds attached on your new harness. If you dont it may only appear that both contacts are 12volts as the voltage path tries to make a complete circuit passing 12v to the ground wire thru the bulb.


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## Toucan49 (May 1, 2020)

GTO44 said:


> It should only have power at the very bottom. The upper portion should be in contact with the body/housing of the light bulb which is ground. It wouldnt be hard to cut the wire coming from the upper portion and splice a length of wire onto it and attach it to a ground.
> 
> on a side note, make sure you have all the grounds attached on your new harness. If you dont it may only appear that both contacts are 12volts as the voltage path tries to make a complete circuit passing 12v to the ground wire thru the bulb.
> 
> 1965 uses only one turn indicator which is fed by either the left or right signal being activated which is why it has two power sources in the socket and as the socket is plastic so it does not ground to cluster.


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## PontiacJim (Dec 29, 2012)

Your options would then be to find/use an original metal socket and splice wires, or, strip a length of wire long enough to allow you to slip the exposed wires down into and on the side of the bulb and add a round connector to the other end which you can screw down to make your ground.

I would go with adding the stripped down wire rather than cut wires and splice.


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## 19gto66 (Oct 14, 2019)

Having same problem with a new M&H dash harness as well. The socket for the turn signal indicator is plastic and has hot feed from the bottom and a upper side; dark blue wire and light blue wire - assuming left and right turn signal lights and would make sense each would be hot depending on which signal was on. The socket is plastic (as my original one was too). I am confused on how it gets grounded as well. However, I was thinking maybe the ground flipped flops depending on which turn signal was on. Guess I will have to study wire diagram and do more volt meter testing to see if the flip flop ground is what is happening. 

I hear the flasher clicking normally. My only other issue is that I do not have the front lights hooked up yet since I took front grill and left fender off of the car. So I was thinking that may be my problems as well...until I read this threat. I was testing the dash lights before putting the seat back in place. Guess I will working on putting front end together first and wait for an answer here or hopefully it's resolve once front end is back together.

Toucan49 please update this threat with a solution if you find one. 

Unless PontiacJim is correct and socket should be a grounded type. But the wires are both blue (dr and lt). So it makes sense for the socket not be grounded in one way. Since there would be a short if socket were grounded with the one wire being hot.



Thanks


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## 19gto66 (Oct 14, 2019)

Just received the below message from M&H. The flip/flog ground is what is happening.

M&H: The turn signal indicator on the dash requires both front turn signal running lamp assemblies be attached with working bulbs and grounds. This system uses the bright filament of the opposite turn signal as the ground. Ex. make right turn, front right turn signal flashes, bright filament for the left turn signal acts as the ground. It is just opposite when the left front signal flashes.


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## PontiacJim (Dec 29, 2012)

19gto66 said:


> Just received the below message from M&H. The flip/flog ground is what is happening.
> 
> M&H: The turn signal indicator on the dash requires both front turn signal running lamp assemblies be attached with working bulbs and grounds. This system uses the bright filament of the opposite turn signal as the ground. Ex. make right turn, front right turn signal flashes, bright filament for the left turn signal acts as the ground. It is just opposite when the left front signal flashes.



Ah, never knew this. Makes sense. The turn signal indicator must have a common power wire to provide the needed 12V which activates through the switch and makes a circuit for the left, or right, turn signals. But when you select left, or right, a ground is created through the opposite position, ie if you turn left, the power routes to the left turn signals and routes the needed ground through the right turn signal to create a complete circuit, and vice versa. 

Or said this way, when you turn signal selector on the column is in its neutral position, 12V power is constant to the signal switch, but no contact is being made until you signal left or right, with the ground contact being made through the opposite signal's wiring which is the bulb contact within its front turn signal socket/housing.

So, if your turn signals are not working, the things to test would be: 

1.) your fuse/fuse box.
2.) ensure you have good bulbs and clean sockets & contacts.
3.) a continuity test for a good ground at the light sockets.
4.) 12V power going to your front turn signals.
5.) the 12V power feed going to the signal switch at the column.
6.) a continuity test for a good ground of both the left/right wiring circuit that goes from the signal switch to your front turn signals.
7.) a bad turn signal switch - contacts worn out and needs replacing.


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## 19gto66 (Oct 14, 2019)

Toucan49 I hope you got your light working.








I love learning new stuff everyday. It makes life worth living!!

Below is a sloppy but functional solution for using a GREEN LEN Bulb in the Turn Signal Indicator socket. I hope to refine and remove the two extra light bulb sockets with correct diodes and make a dummy bulb to connect to existing bulb socket so not to damage existing wire harness. If anyone has done this please let me know since I have very little knowledge of correct diode to use.

After I put my dash all back together I forgot the Green plastic film used to make the light look green on dash when your left or right turn signal was turned on. So I thought I would simply use a GREEN LED until I learned of the +/- swapping. Once that happen I said...now what do I do. We will see. I still might just find a piece of green plastic that won't melt and cover an 1895 bulb (manual states to use 194 bulb but 1895 seems to work as well)


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## Toucan49 (May 1, 2020)

19gto66, great work tracking this down. My front turn signal lamps are not presently connected but today that will be the first thing to do, so I am thinking the problem will be solved. As the indicator wires are light and dark blue those match the front turn signal light feed colors. Will be great to move past this issue, one step closer to putting her back on the street. Thanks


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## 19gto66 (Oct 14, 2019)

I am learning something new everyday. Learned they sell LED 12v bulbs that are *NON Polarity Sensitive* in Green so I am hoping they will work in the current two blue wire turn signal socket without doing anything else. 

Here's my source: SuperbrightLeds.com part: BA9S-G4-32-12VAC 
Angle 32 degrees (closest to spot I could find)
Volts 12V DC/AC
Brightness: 20lm (should be pretty bright for a dash bulb)
Draw: 0.03A
Pricey ($1.98 ea) but if it works without having to make my contraption it's worth it.


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## Toucan49 (May 1, 2020)

Toucan49 said:


> 19gto66, great work tracking this down. My front turn signal lamps are not presently connected but today that will be the first thing to do, so I am thinking the problem will be solved. As the indicator wires are light and dark blue those match the front turn signal light feed colors. Will be great to move past this issue, one step closer to putting her back on the street. Thanks


As an update, I connected front turn signal lamps to the wiring and the dash indicator is flashing like a college girl at mardi gras, thanks


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