High beam indicator in gauge cluster does not illuminate

[notny41]

Hey everyone,

I have a 1986 944 Turbo that when I turn on the headlights and switch them to high-beam, the little blue light on the dash does not come on.

I pulled the gauge cluster out and removed the bulb and tested it with an ohmmeter and it gave me a reading of 13 ohms.

Can anyone think of any reason this would not be lighting up. I'm not sure when the last time I saw this working.

[Tom]

If I'm reading the schematics correctly, the high beam light on the dash is powered by pin 1 on plug B of the cluster, via a blue/white wire that is connected directly to the headlight high beam power wire -- i.e., when the high beams have 12 volts, so does that buld in the cluster. Dumb question, but I assume the high beams are working? If so, I'd check for power on that blue/white wire when the high beams are on. If no power, then somewhere between the cluster plug and the headlight harness, that blue/white wire is not connecting. If you have power on that wire at the cluster, then I'd check for continuity between pin 1 on the cluster's edge connector and the bulb socket. If that checks out, then I'd clean all the little football-shaped connectors and edge connectors and confirm the socket is getting a good ground. And before any of that, I'd probably hook up 12 volts to the bulb to make sure it actually works. 13 ohms sounds like a functional bulb, but until you see it light up, I'm not sure you can say with 100% certainty that it works.

[notny41]

Tom, thanks for diving into the schematic. I did end up sorting this out. I pulled a bulb out of one of the lesser needed dash lights (I think it was an up arrow - assuming this is a light that tells the driver to shift up into a higher gear possibly?) and put that into the high beam indicator spot and now the dash shows me when the high beam lights are on.

So here's what ended up being the problem:

(In my attempt to get the bulb out of the little housing thing I ended up breaking the bulb and then discovering that it is not a socket/replaceable bulb - I'd need to buy the bulb/housing all together)

Anyway, as I was inspecting the housing, I noticed that there are supposed to be two metal wiper tabs (one on each side) that make contact with the gauge cluster pcb board when you twist the bulb housing in. Mine only had a metal tab on one side of that bulb holder. So even though I was testing ohms across the two metal ears that hold the bulb housing to the cluster board, the contact was not being made when it was installed because of that missing metal tab.

dash bulb.jpg (214.27 KiB) Viewed 985 times

I've never seen that little up arrow come on while driving (it did used to illuminate when you would turn the car on, but that was the only time I ever remember seeing it come on). So I'm not too worried about no longer having that indicator.

[notny41]

Here are some more pictures of this little thing disassembled:

bulb taken apart.jpg (228.29 KiB) Viewed 982 times

bulb tab.jpg (150.74 KiB) Viewed 982 times

bulb no tab.jpg (162.64 KiB) Viewed 982 times

[Tom]

Glad you found it and great pictures of the issue! I knew I was geeking out too much on the schematics.

[notny41]

Yeah somehow I had a feeling it was something dumb. before i tore the gauges out, I was certain it was just a burnt out bulb. Glad I didn't have to dig into the wiring.

Sorry I didn't try a different bulb before asking the question on the forum and having you do unnecessary work.