Grounded Bulb Connector from Steering Harness

[kansasc10]

Ive replaced all the wiring in my 72 C10 and am having issues figuring out where the grounded bulb connector coming from the steering harness is supposed to go. It looks a lot like all the other bulb connectors in the back of the dash (turn signal and dash light bulb connectors), but this connector is white instead of black and its connected via a black wiring coming out of the steering column. Can someone tell me where this should be connected and what its used for? Is it supposed to go in one of the holes in the back of the dash?

[firedemon]

not sure but it looks like the one on my heater switch

[kansasc10]

Originally Posted by firedemon

not sure but it looks like the one on my heater switch

Is there a hole to attach it to on the back of the heater switch? Does it only come on when the heater is on? Thanks for your time!

[firedemon]

theres a hole in mine where the words are on the back it comes on when the dash lights come on

[Clavo106]

thats funny I just pull out the my harness yesterday. mines a 1970 so it could have changed. mine has a light in the heater control box.. its a biger hole in the assembly for the light. but my wire is gray. witch matches the wire diagram. I have. . and mine connector looks different. then yours.

[leftybass209]

That goes in the back of the dash, it's a bulb for your dash lights. Make sure it's in a constant power spot and not an indicator, or dummy light location. The fiber optic element runs to your column indicator to light that up, so there isn't any bulb in your column like a tilt has.

[chiefcfd]

Like he said in the above post. It lights up your shift pattern on the column.

[swamp rat]

Its an optocal lead that go's to the shifter indicator so it lights up at night

[kansasc10]

Thanks for all the replys I definitely learned something today. Any advice on which hole in the cluster to connect it to? Im thinking the hole circled in red below but not sure if it has constant power or not.

[OUbesto]

Was there ever a resolution on the "grounded bulb"? I'm having same issue so any follow up advice is appreciated.

[LockDoc]

Originally Posted by OUbesto

Was there ever a resolution on the "grounded bulb"? I'm having same issue so any follow up advice is appreciated.

It is the light for the fiber optic cable that lights up the shift indicator.

http://67-72chevytrucks.com/vboard/s...d.php?t=682436

Post #4 has a couple of pictures.

LockDoc

[OUbesto]

Leon, after reading more threads, I believe I am getting closer to understand what I'm dealing with in my tilt steering column and trying to get shift indicator light to work. I found one of the grounded white plastic bulb housings tucked up under dash but not plugged in to back of instrument guage panel. Having said that, My gear shift indicator has a bulb located just under the shift indicator housing that comes off with two tiny screws. I'm guessing PO replaced 70 steering column with a tilt version from a later year. Since tilt columns used a bulb, PO probably just tucked the fiber wire up out of the way. (BTW, I'm the same guy you helped with the horn related issue that I just resolved.) I see there is a gray wire attached to the shift indicator bulb (Tested bulb and it is good.) that I think goes into the rounded wire harness. All of my other guage bulbs, turn signals, hazards, all work. Where does the grey wire go?

[FirstOwner69]

Originally Posted by OUbesto

Where does the grey wire go?

Connect it to the cluster feed terminal on the fuse block. The bulb will light when the exterior lights are on and dim with the dash lights.

[OUbesto]

Thanks FirstOwner69...I did find a gray wire connected to the cluster feed terminal on the fuse block and I reconfirmed via continuity test that there were no breaks in the grey wire. I also confirmed there were 11+ volts into the base of the base of the bulb holder in the gear shift indicator. I even grounded my tester to the bulb fixture's brass holder to make sure I had a good ground in the base. Tested the bulb and it was good. So Im thinking once I insert the bulb it should work and.....NOPE! I even tried to push bulb down and wiggled it inside the holder to see if I could just get it a flicker...nothing! Last resort I placed a small dab of dielectric grease on the bulb...still nada! Anyone have any other thoughts? I'm not sure if it has the correct bulb and I cannot read the size anywhere on the base. Anyone know correct bulb ?

[OUbesto]

I found another forum thread that bulb #1994 is correct one for the shift indicator. Looks like I'm missing a part (green filter).

[FirstOwner69]

Originally Posted by OUbesto

I found another forum thread that bulb #1994 is correct one for the shift indicator. Looks like I'm missing a part (green filter).

The green filter isn't essential. It merely makes the light color close to the cluster lighting. Probably dims it a bit too. I've never heard of a #1994 bulb. I think you want #1445.

Sure sounds like it may be something other than the bulb though. Very dumb question... you did have the light switch pulled out when you tried it with the bulb in. Right?

[OUbesto]

I'm not exactly sure how/where I typed #1994 because I wrote it down as #1445, doh! I'm glad you pointed that mistake out to me before I would be running all over town trying to find the wrong bulb! And not a dumb question, but I did have the light switch pulled out and tried to rotate (dim) it as well just in case I saw something flicker etc..