Tach Wire on Distributor but No Tach

[JKRamsey1991]

I am in the process of installing an AutoMeter tach in my truck. Went to run the wire to the distributor and found it already has a wire on the tach signal plug on the HEI distributor. The truck is an 86 carb'd truck without a factory tach. What is the gray (maybe white) wire that is currently attached to the tach output going to? I could trace it but figure asking is easier lol

 

[Sad Sack]

I've seen some just run to an empty connector on the bulkhead. Did you follow your wire to where it terminates?

 

[Scott91370]

IIRC, white is the correct color and it should go to the bulkhead then to the dash cluster.

Gonna have to trace it to know for sure.

 

[Grit dog]

Easy quick first step, unplug it and see if anything stops working?
I don’t have the wiring memorized on these trucks but could it be going to an operational or now defunct cruise control?

 

[bucket]

Someone has added that tach wire, who knows where it goes (other than to the dash area somewhere) or how well it was done.

 

[Ricko1966]

Someone has added that tach wire, who knows where it goes (other than to the dash area somewhere) or how well it was done.

We could guess. I guess it goes to the ashtray if it's actually white. If it's grey I would guess it goes to the passenger side mirror.

 

[JKRamsey1991]

Its a factory wire. The plug is factory two connection with both the hot switched and the tach in it. Ill try to trace it and see where it goes. Was trying to be lazy and avoid pulling the harness apart any lol

 

[bucket]

Its a factory wire. The plug is factory two connection with both the hot switched and the tach in it. Ill try to trace it and see where it goes. Was trying to be lazy and avoid pulling the harness apart any lol

Those pigtails can be bought. It's a clean way of installing a tach.

I can't think of a single thing on an '86 that would have possibly used the tach signal to operate.

 

[nvrenuf]

Its a factory wire. The plug is factory two connection with both the hot switched and the tach in it. Ill try to trace it and see where it goes. Was trying to be lazy and avoid pulling the harness apart any lol

Wait! I could be wrong because it's been a looong time so @bucket etc check me.... Isn't there a 2 wire plug that's installed close to the body of the cap and the tach wire would be in an outer spot labeled "tach"? I'm thinking the 2 wire plug goes to the module.

@JKRamsey1991 I can say with 100% certainty that the factory tach wire is a single wire, single slot plug at the distributor so if you have a 2 wire plug that's either not the tach slot or not factory. Factory tachs use a stand-alone harness with only 1 wire going to the dist cap (plus ign, etc wores).

 

[JKRamsey1991]

Wait! I could be wrong because it's been a looong time so @bucket etc check me.... Isn't there a 2 wire plug that's installed close to the body of the cap and the tach wire would be in an outer spot labeled "tach"? I'm thinking the 2 wire plug goes to the module.

@JKRamsey1991 I can say with 100% certainty that the factory tach wire is a single wire, single slot plug at the distributor so if you have a 2 wire plug that's either not the tach slot or not factory. Factory tachs use a stand-alone harness with only 1 wire going to the dist cap (plus ign, etc wores).

Theres the inner plug that goes from the distributor body to the cap thats multi prong but this is the outer one from the main body harness. The connector looks like this but instead of green its white or gray (dirty and old so a bit hard to judge)

You must be registered for see images attach

 

[nvrenuf]

I had a factory tach in my old ‘80 K10, the harness had a single wire to a square plug that only connected to the tach terminal on the cap. The ignition wire was a separate single wire connector.
I still believe your 2 wire connector is not original, you need to trace the wire from the tach terminal.

 

[saltdog]

I've got a separate tach wire to distributor and no tach. Its factory. Nothing breaks when unplugged, but haven't traced where the other end goes.