Hi Guys,

Just one final electrical issue to sort out on my BB. When i flip the turn signal stalk up and down, the right and left exterior lights function and flash as they should, but the blinker indicator light on the dash only lights up for left turns. This is a 74 black center gauge with one light for both directions.

Any ideas?

My 74 1.8L has working signals but sometimes the gauge indicator will blink as per the contract and other times it gives a couple blinks and then stops. Is that what you’re getting or are you normal function one direction and zilch on the other?
I assumed I had some relay issue….

Thanks, Van. The dash indicator flashes normally when making a left hand turn. No dash light when going right. But all exterior lights work as they should.

Hey Ian
Get a look at the back of the indicator bulb.
Are there two powered leads to the bulb or one ? Note the tracer colors.
Complete speculation here but follow that lead or leads.
Also, I ve seen all kinds of flashers in our cars....some suitable and working....
others cobbled and with issues.
Happy New Year !!!
Hope to see you soon.
Rory

Hi Ian: Having a look at this, it appears that the lead for the indicators comes from the relay. Maybe try cleaning everything between there and the lights. Or it may just be bad.

Click to view attachment

Thanks, guys. If I'm reading the above diagram correctly, the L and R dash indicators share only one signal path, and if the relay were bad, neither directrion wold work, no?

Ian pictured is the OE relay.
I think that is the problem.
When either choice is made a signal goes to the C post.
I think that path works on only one side in your relay.
You can remove the cover and possibly clean the contact points.
Also you can observe the action by operating the directionals with the cover off.
I've had luck with relays in the past.

This may be a silly question to ask, but you said it's a '74 black center gauge. Is the car a '74 as well? I know the 74-76 with a common light work differently than the 70-73 with independent indicators.

Yep It's a 74 car. Thanks, Rory for the fun shot of the relay. I'll check it out and report back.

Hi Ian. You have probably already checked this but I thought the relay not blinking in one direction meant a bulb out (front or back) on that side.

I have a 74 as well and ended up moving away from the OE relay pictured above as it only blinked once for either turn signal or hazards. I am using the Spokes bodge job on a new relay which works but not exactly as the original did - the turn signal indicator blinks with the handbrake light as well … He modifies and sells them and provides instructions to do it your self, as I did. https://www.spokeworksled.com/914-led-solutions?page=2

Still thinking about getting in there to see if I can get it working.

On my 74 I’ve found that only the one hella flasher relays work correctly. All the aftermarket ones are wonky though haven’t tried one from Spoke. IIRC the action for a bad bulb is continuous on/off blinking.

The OEM flasher with the single tach indicator will not flash the indicator if the OEM flasher senses a burned exterior bulb. This is a safety feature from the factory.

In your case my guess is the secondary coil is weak and the current from the left hand exterior bulbs is greater than on the right. The right side either has a bulb out or the bulbs are lower power than designed. Or the sockets are dirty and some loss of voltage is causing lower current on the right side. Try cleaning the sockets and check all connectors Maybe remove and replace all connectors.

If this doesn't help then try replacing with LED-compatible EP26 flasher. I resell the EP26 with the C2 pin connected to 12V when flashing just like the OEM flasher. You can buy EP26 almost everywhere but the C2 pin is not connected to anything and needs to be connected inside the flasher. You can buy from me or follow the directions on my website to wire yourself. Only one wire is added; no traces need to be cut or any other mod.

Resistance in a circuit can cause all sorts of weird stuff to happen. Good example is a bad ground. The power needs to flow evenly, a blown bulb, a bad ground, corroded connectors, a fatigued wire that looks good but the metal is cracking inside causing resistance. Gaads, it is hit and miss. If you had the values of everything you could use a meter, maybe someone has put that list together too. The turn signal switch works with the relay, if there is the wrong resistance in one of those paths..."There's no place like home..." Mine is a 72', every once in a while the left blinker indicator would blink once and then both would flash dimly. Blinkers were working fine. Next time I'd hit the left blinker it would be fine, and continue to be fine for a long period of time. I never did figure that one out.

@Shivers

The secondary coil that drives the common connection of the tach turnsignal indicators has lost its efficiency over time and is not pulling in with turnsignal on. Thus both L and R indicators flash together.

Two basic solutions:

1) Remove the common connection of the L and R indicators and ground them. Many people just install a new relay or put in an LED-compatible EP26 relay.
2) New flasher relay.

I grounded the common connection of the L and R indicators on my '71 when both indicators flashed together.

BTW, the L and R flashing together is designed into the OEM flasher relay to alert the driver that an external bulb is burned out. Over time the secondary coil loses its efficiency and you have the situation observed on your car.

Thank You Sir! That makes sense, I think I'll ground them.

@Shivers

Here's how to do the grounding of the common wire. Remove the wire on the common connection and tape up the wire so it doesn't touch anything as it is still connected to the flasher relay.

The pigtail connects to the common connection and the other end to the ground connection for the tach.

The 2:1 connector can be found at Digikey if you can't locate one:

https://www.digikey.com/en/products/detail/...-250P-Q/9491269

Click to view attachment

Click to view attachment

Click to view attachment

Click to view attachment

@Spoke That's great...Thank you