• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

TR6 TR6 TURN SIGNAL PROBLEM

Share this page

C

ceedub

Senior Member
Country flag
Offline
Just completing the last wiring hookup on our '74 TR6 resto. We have a new wiring harness, new hazard switch, new turn signal flasher and new turn signal switch. The hazard lights work well. When the left turn signal is chosen the left signal works well but the right signal is on as well but very faintly. The right signal does not work at all. We thought about a bad ground but the hazards are working fine so the lights must be grounded well. We've tried several different turn signal flashers as well. Could the problem be internal to the hazard switch or have we wired a plug incorrectly or is the flasher unit the issue? There is a definitely a 'bleed' somewhere that both left and right come on at the same time. Thanks in advance for your input.
 
Are you using LED's for turn signal lamps?
 
Not sure, but I wondered if a small amount of voltage leaking through the dash indicator bulb would make the RH signals faintly light up. It doesn’t take much current to light an LED. Try switching the bulbs back to incandescent.
 
FWIW - I recently replaced my turn signal switch and one of the drive rivets that hold the little pawls in place came out in my hand. I found that a 4-40 machine screw threaded in with a little resistance - like a lock nut. Suggest anyone with a replacement switch do this before installation.
 
I guess that it would be worth swapping out the LED bulbs with incandescents but how would that account for the right side not working at all? A completely different issue or somehow related?
 
ceedub said:
I guess that it would be worth swapping out the LED bulbs with incandescents but how would that account for the right side not working at all? A completely different issue or somehow related?
Click to expand...
Just a guess.... It's possible that it's related.
The right side may not work with the LED's since the polarity gets changed switching from Left to Right and LED's are dependent on the correct polarity. Switch back to incandescent bulbs and let us know if things return to normal. By the way, what kind of bulb do you have in the turn signal indicator in the dash?
 
the LED's are your problem. Because the turn signal indicator in the speedo is connected to both sides (it blinks when either left or right is activated) a certain amount of current bleeds to the other side, so both sides will flash. You need to install a resistor (available from Moss and others I suspect) or just use LEDs in the back and incandescent in the front. the incandescents will provide enough resistance to stop the cross current.
 
I'm sitting here looking at the wiring diagram, and, yes, it seems possible that there could be a small leakage current through the dash indicator light to the opposite side. It's not unusual for cars to use the "off" lamp as a ground return for the dash indicator; my Porsche 912 does the same thing. But it looks like both sides should behave the same way. The reason for the right side not working is still unanswered. BTW, there is no difference in polarity between the two sides, so I don't think that's an issue.

I suspect you have a small wiring error.
 
Steve... I it may be possible that the right side doesn't work if he has an LED indicator bulb in the dash. If he did, then then the right side would not get +12v since the diode (bulb) would not let the current flow in both directions like a filament would.
I have an LED indicator bulb in my TR6 and to get around the changing of polarity on the indicator bulb I used two diodes like the schematic and my LED indicator on the dash works either Left or Right.
IMG_2586.jpg
 
Ah, I see what you mean. I was about to suggest your circuit as a way to avoid using the turn sigs as a return path for the dash indicator.

I understood the first question as saying that the right turn signal didn't work, not just the dash indicator. In any event, if the right turn sig doesn't work, there is still a problem.
 
The bulb in the turn signal indicator is incandescent. We can't get back to the car until next week and at that time we'll try pulling the bulb on the indicator and see if that makes any difference. I was reminded that the harness does have a resistor on each side that was installed when the LED's were installed. I will let you know what we find. Thanks again for your insights.
 
A FOLLOWUP: Thanks again for the info on the LED's in the turn signals. We took your suggestion and replaced the front LED's with two incandescents and the bleed was fixed. We would never have picked that up ever! Why the right signal did not work was another interesting discovery. We took the turn signal switch out and studied it carefully only to find that from the factory the colour coding was wrong. The power line (LG/N) from the turn signal flasher was soldered to the left signal post instead of in the middle of the three posts. We solved that by switching the plugs under the dash and our signal problem was fixed. I wonder how many other switches made it out of the factory with the same mixup.
This forum is an invaluable resource with great contributors.
 
So you got the switch from Moss is that right. Electric circuits look for easy pathways and DC is no exception I believe the Diode is the fix. I did all the dash gages but not the turn indicators or tail lights 1157's. I do not like to speak badly about Moss this just happens to many time. Just try to stay with UK parts from any supplier ask where it comes from. I got a new OEM radiator for TR 6 1973. all I asked was did it come from China VB would not say where it is made. When I got it all was correct and fit came from Thailand. I ounce lived there so I was OK with that. Madflyer
 
Back
Top