FRporscheman

Our '95 has this new problem where turning on the headlights (or even just parking lights / markers) will cut the power to the temp display gauge. I haven't done any modding or wiring. The car is stock. It was working fine a few months ago and now it has this problem, I can't tell you exactly when it started since I don't drive it that often, it's my mom's car. Turning the lights off will make the temperature display come back on, in Celsius.

Any ideas or BTDT? I don't even know where to start.

9ines

I have the exact same problem. It is very annoying. Anyone know of a fix short of replacing the unit?

-kb

Roman 968

Hi! may be it ground wire on temp display gauge, loss of contact. check the voltage between the brown and red / green wire on temp display gauge.

C ANDERSON

Change the bulb in temp gauge it's blown. should fix

Miles968

1+ on changing the bulb

Thom

Check your fuses.
I regularly blow this one when I fiddle with the glove box light without disconnecting the battery.

FRporscheman

A bad bulb will cause this problem?

The bulb is an led, and it worked fine with it for months. My other 968 has the same led and it has always worked fine..... I'll take the unit out and inspect. I'll try swapping the LED out for a regular bulb as well.

User 41221

An interruption of power will make it display in Celcius, I have experienced that when I blew a fuse (iirc, the same circuit is tied to the power mirrors and instrumentation lighting), so you have something funky going on there. I'd look closely at the headlight switch if the temp bulb is good.

FRporscheman

Yeah I know that when the temp display loses power and comes back on, the default is Celsius, so I'm not so worried about that fact. Thankfully the Fahrenheit function works fine, if I bother to switch to it.

I didn't think of the headlight switch, I'll look at that too, thanks!

968rz

Mine stopped working in my 93, I checked everything and found no bad grounds or blown fuse. I ended up moving the lite from the cigarette lighter to the temp gauge.
It does not come on every time the key is on like it used to but I don't really need that during the day and at night with the lights on it works fine (never use the lighter any way).

968 GUY

I think both my 968's do that. It is aggravating but I thought it was normal. Never have checked the bulbs tho.

blackboy

What would be a good source for the bulb on the temp. gauge? Dealer, auto parts store, or ?

FRporscheman

I'm sure it's cheap from the dealer. By cheap I mean about $3... The 25-cent LED and resistor combo works great too, though.

I haven't had time to work on this problem yet (too many other bigger projects), but while I was working on my other 968's dash, I had its temp display unit out, and I noticed it had a bypass wire soldered in the back of it. It looked like it was done well. Maybe a dealer fix? Both POs were middle-aged business women who always took it to the dealer, so I tend to think this bypass wire might be a dealer-implemented fix, and it leads me to believe they may have seen this problem enough times to have developed a fix like this. All the wire does is connect a solder joint at the bulb to one of the connector prongs (bypassing the line on the circuit board).

It can't hurt to try it, assuming the other simple things look ok.

blackboy

I went to the dealer today and they could not come up with a replacement and the parts guy said he doubted that it could be ordered. Does anyone have a part # for this? Also does the bulb itself come out of the plastic holder or is it replaced as one complete unit? Thanks.

Thom

Can one post a picture of how the back end of the temp unit looks like?
I would be surprised if the bulb wasn't the exact same as the one for the 944 clock.