Car is 76 with new late wiring harness. Initial wiring checkout after harness install.
Turn signal on, front & rear run lights flash as intended but signal light on tach just comes on once momentarily. Is this normal, or do I have a wiring issue ??

Well, i tried all 5 of my stash of flasher relays, several showed same symptom of single flash, but 1 worked OK.
Now the hi beam indicator bulb works fine but does not show thru to front of Tach,
Don't know whats up with this

When you use the emergency flashers do the dash indicators flash as expected?

I remember this being a symptom of a failing flasher relay.

--DD

+1

Still is. Sometimes they fix themselves with use, but don't hold your breathe.

Well, I swapped in another flasher relay from my stash and the dash indicator flashes OK with the F & R lamps using emergency switch.
When i tried the turn signals the indicator lamp started flashing OK, but turned the turn signal lever to the other side and the prior single illumination returned .
Trying the emergency flashers again and indicator lamp flashes OK, but both turn signals just flash once.
I'll try another of my relays to further research this.
Yes, one of my spare relays is working OK. All seemed to work with emergency flasher, but only 1 worked with turn signals.

Now my problem is the hi-beam indictor lite bulb is OK if I pull the lamp out of the tach, but it does not show thru to front of tach, what's up with this ??

Bump for hi-beam indictor lite problem

This may just be the blue colored film in the tach - someone else posted recently that whatever material VDO used gets more opaque with 40+ years age - so the bulb is working but doesn't show through. I had the same issue in my car.

Sadly - if this is the case - you have to pry the VDO can open to replace the film which can be messy....

- Tony

the bulb holder has a knurled contact make sure the contact is not worn and that it contacts the bulb.

Next, the "light pipe" on the gauge is the ground path. make sure that the black sleeve of the light pipe is preventing the bulb holder to ground.

Also check the ground wire for the gauge itself "rings out" to ground.


Those are my thoughts having had this same problem

Good luck......hate those electrical problems.

The failure of the turnsignal indicator is common in the OEM flasher. See the flasher below on the top right. Notice the relay coil in series with the 49a pin. When the flasher is flashing, the heavy bulb current causes this relay to close and the tach indicator to flash.

The relay coil loses its efficiency over time and the tach indicator may flash once or not at all. Usually it will still flash when the 4-ways are used.

I resell the commonly available EP26 flasher which is pin-compatible with the 914 OEM flasher. Unfortunately the stock EP26 does not have any connection to the C/C2 pin for the tach indicator. I modify EP26 to make the C/C2 pin drive the tach indicator.

The high beam is because the light is working but the blue material is so old and weathered that it has gotten to the point where no light will shine through it. To fix it you would need to pull the gauge out of the dash, then pry the trim ring off, then you can get to the material and change it out.

I went in thru the lamp socket with a Q-tip, but it didn't show any dirt, was afraid to use acetone on it.
However, there are 2 styles of illumination sockets used on our cars, the one initially for the hi beam indicator is a tiny bulb with exposed leads that plugs straight into the housing. The sockets used for instrument illumination use a larger bayonet style bulb (higher wattage ??) anyway using one of these I had as a spare now projects enough light to be seen.
Barefoot

I agree, new flasher relays mounted on the fuse block have an extra terminal that has to be connected

Now on the the next problem areas:
First; where is the rear terminal for the oil temperature gauge ?? wiring diagram shows green wire with black stripes on current track 54 to center console gauges. there is a wire with these color markings running back thru the harness in mid cockpit, However, neither the 12 or 14 pin connectors on the rear relay board have such a connection depicted. Where do I plug in the wire from the taco plate temp sensor ???

NEVER MIND, found the elusive green w/ black stripe comes out near the 4 big red wires that go directly to battery.

Second; to hook up an oil pressure gauge, (not the idiot light), are there any provisions in the late wiring harness for this option, or do I have to run a new wire for this gauge ?

I had my gauge (911) setup to flash left and right,on testing I found response on one side and sometimes on the other direction,the relay was sluggish so swapped out for spare problem solved.

On a 76, look for a single green/black wire with a single box termination in the vicinity of battery, either above or below the engine tin. Thats where the oil temp sender wire connects.

You'll like have to run a new wire. Unless your car is wired for options that weren't installed (e.g., rear window defogger) there won't be spare wires.

--DD