dash light on and i dont no what it for

[65 on 24's]

the tandom lock i think that how it is spelled and way it is on and i dont no what it for.

[zenish]

the light socket hangs by a wire.my guess is that thats the light for something else in the wrong hole.

[65 on 24's]

so if i look behind my dash and i find out what color that wire is that the light is on can yall tell me what that wire is for

[zenish]

when dose it work?if its on only when the headlights are on,its supposed to be lighting the cluster.is part of the cluster darker than the rest?

[cst70rocket]

Tandem lock is for a big truck dash! The dash originally came from a truck with two drive axles, and you can lock both of them in for no mo stuck hopefully. I don't know why it's on unless it's a ground switch and it's ungrounded.

[Captainfab]

Originally Posted by 65 on 24's

so if i look behind my dash and i find out what color that wire is that the light is on can yall tell me what that wire is for

All of your dash lighting wires should be gray. Just turn your lights on or do whatever needed to get that light to come on, and try unplugging sockets in that general area until that indicator goes out. then find another hole to plug it into, that is for illumination of the dash only.

[six4flat]

i looked on my brothers dash of his 66 and he has that light on too, he says its been on since hes has had it

[65 on 24's]

ok i just look that wire was a gray wire so i fix that. i have 1 more ? way when i push my brakes my blinker on my dash come on and the blinkers on the frount of the truck come on.

[Captainfab]

Since the turn signals and the brake lights use the same element in the bulb, it sounds to me like a bad ground. What's probably happening is if one of the tailights doesn't have a good ground, when you push on the brake it is grounding thru the turn signal wires and lighting up everything. Try checking all the ground wires having to do with the brake lights. Even if they look good, remove the screw and file,grind or whatever to get down to bare clean metal on all pieces involved.

[k14burb]

My brakes are kinda crappy, whenever the booster seems to loose vacuum, the tandom light turns on. I just pump the brakes and when it gets vacuum again it turns off. WTF? I dunno.

[65 on 24's]

i no is not my back lights cuz i have a wire going from the tail light housein down to the frame cuz it was not get a good ground befor so could it be the blinker in front not get a good ground makin it do it

[Captainfab]

Originally Posted by k14burb

My brakes are kinda crappy, whenever the booster seems to loose vacuum, the tandom light turns on. I just pump the brakes and when it gets vacuum again it turns off. WTF? I dunno.

Sounds to me like the brake pressure switch in the proportioning valve(if your truck is equiped with one)is wired up to light the 'Tandem Lock' indicator. Did you build the truck? including the wiring and brake system?

[Captainfab]

Originally Posted by 65 on 24's

i no is not my back lights cuz i have a wire going from the tail light housein down to the frame cuz it was not get a good ground befor so could it be the blinker in front not get a good ground makin it do it

If you're certain that the tailight housings are grounded good enough, then the problem could be in the turn signal switch in the column. Some 20+ years ago I had a 63 4x4 Suburban that was giving me fits with brakelight and turn signal problems, and I finally found the problem inside the turn signal switch. What had happened was the little brass contacts inside got bent and weren't releasing. Give that a look.

[k14burb]

Originally Posted by Captainfab

Sounds to me like the brake pressure switch in the proportioning valve(if your truck is equiped with one)is wired up to light the 'Tandem Lock' indicator. Did you build the truck? including the wiring and brake system?

That sounds pretty logical, thanks. I bought the truck from the second owner who had owned it since '71. He did some interesting mods and probably did wire the light to the brake system when he swapped in the 10 bolt/disc. Sometime I'll have to check it out. The wiring is real funky, with add an on AC system and a fuel mixture gauge wired into an o2 sensor in the exhaust.

[slepysal]

man I feel you, my wiring for the turn singals/ brakes are a mess. the brake light is wired directly from the switch to the brake light. The turn signals operate from a toggle switch on a panel. Gehto at best. but it works.I plan on fixing it when I istall my tilt.

[Chevyboy1962]

Is the steering column the original one, or do you have a newer steering column with hazards installed?

It's probably a bad ground if it's the stock steering column, but if it has a steering column with hazards built in, try pulling out on the tab.

My '62 originally had a '67-'72 non tilt steering column with hazards built in when I frist picked it up. I had to pull out on the hazard knob to make the dash lights & front left blinker in the hood to go out to work properly.
David

[65 on 24's]

newer steering column with hazards installed but the hazards are not hook up and about 2 week ago very thing was workin fine

[65 on 24's]

and my grandfather started biuldin the truck and im finshin it

[65 on 24's]

well it not a ground cuz i grounded it to the - on the battery and it still dose the same thing

[mateo1279]

The "Tandom Lock" light turns on in my 62 C-10 right when I start it up (80% of the time). If I rev-up the engine it turns off, if I don't 'rev-up' the engine and attempt to drive, it stalls... I know this doesn't answer any questions, but it might help determine function, which could lead to an answer (I am also curious what this light is for).

-Matt

[mateo1279]

or my wiring is severly trashed....

[Fastrucken]

Originally Posted by mateo1279

The "Tandom Lock" light turns on in my 62 C-10 right when I start it up (80% of the time). If I rev-up the engine it turns off, if I don't 'rev-up' the engine and attempt to drive, it stalls... I know this doesn't answer any questions, but it might help determine function, which could lead to an answer (I am also curious what this light is for).

-Matt

This one sounds like alt light which also energizes the field of your alt. to test turn ingition on but dont start the truck then.... if you have an external regualtor, unplug the connector going to it. If you have upgraded to a internal reg alt then unplug the connector on the alt.

If the ligh goes out then its the alt light.

[Fastrucken]

Originally Posted by Captainfab

Sounds to me like the brake pressure switch in the proportioning valve(if your truck is equiped with one)is wired up to light the 'Tandem Lock' indicator. Did you build the truck? including the wiring and brake system?

ditto for brake proportioning valve light. my guess is the PO upgraded the brakes to a dual chamber master cyclinder, and the light lets you know when the proportioning valve is not centered usually means a leak somewhere.

GRaham

[LILRED66]

All of the '64-'66 Chevy truck dash clusters with factory gauges have the Tandem Lock in the dash. I have 40-50 factory dash clusters and every one of them, when disassembled, has this in the dash. The hole in the back of the dash is backed up with a card board cylinder that transfers the light to the front of the dash bezel. On the front of the card board backing up the bezel is a red semi-translucent cap. If the light socket is not plugged into the hole it is not backlit, therefore you can not see it. You have a light socket plugged into the wrong hole in the back of the dash. If it is a gray wire it is for the general back lighting of the dash, when the park lamps (second position) or head lights (third position-all the way out) are on.

If you had a C60 or a big bolt with a tandem rearend set up or a two speed rear axle, that is engaged, this light would illuminate.