backlight out when dark... coincidence?

[89z51l98]

When its dark, I can't see my guages... I figure it is one of two things... its cooler and there is a connection problem... or there is a photocell that dims the guages when there is less light and it isn't working. I ordered a FM but am still waiting for it... rrrrrrrr

thanks for any input...

[Vettelt193]

did you turn the headlight knob? on your year, twisting the knob changes the 'dim' on the interior lights only when the lights are on

[89z51l98]

I have played with that... and when the backlights are on the dimmer works. It may be a connection problem that is effected by temperature... sometimes during the day the backlights will go out too. I need to try to isolate the problem... whether the backlights aren't getting power correctly or if there is a problem with the cluster itself. I understand from the knowledgebase here that they are little halogen lights... like the expensive ones for the high brake light...

Originally Posted by Vettelt193

did you turn the headlight knob? on your year, twisting the knob changes the 'dim' on the interior lights only when the lights are on

[Vettelt193]

Originally Posted by 89z51l98

I have played with that... and when the backlights are on the dimmer works. It may be a connection problem that is effected by temperature... sometimes during the day the backlights will go out too. I need to try to isolate the problem... whether the backlights aren't getting power correctly or if there is a problem with the cluster itself. I understand from the knowledgebase here that they are little halogen lights... like the expensive ones for the high brake light...

yes to the expensive halogen part, but I have heard you can swap the lights out for very cheap regular bulbs with the same result.

You may try pulling the dash cluster out and making sure nothing is loose or corroded. It may be an obvious fix... I hope it is, because electrical problems always seem to be a real pain to find

[Hrtbeat1]

If you have to pull the cluster check the grounds. There are a number of them. I've heard of people fixing the early C4 guage cluster electrical woes by splicing in good grounds to the ground points. Hopefully your FM will have section 8A Electrical Wiring/Schematics (mine doesn't ... its a seperate book). Our cars changed a little between the years, maybe the manuals did too.

[Ken]

There is a photocell that controls the brightness of the dash lights.

[89z51l98]

Ah HA!

Thanks...

Originally Posted by Ken

There is a photocell that controls the brightness of the dash lights.

[Vettelt193]

Originally Posted by Ken

There is a photocell that controls the brightness of the dash lights.

Doesn't that make the dash go from dim to bright (not off to bright)? It could make a difference in troubleshooting. These stinkin' electrical problems... there is a sensor for everything

[Moonunit 451]

Originally Posted by Ken

There is a photocell that controls the brightness of the dash lights.

The photocell is at the top left of the left hand or RPM display on the dash on my 86. It's about a 3/8" square open hole. If you cover it in the daylight the dash will dim to whatever you have the reostat from the headlight switch.

After I replaced the dash bulbs I considered covering it cause the dash was SO bright during the day, but I got used to it. The dash defaults to FULL bright during the day. Sounds like a bad photocell or a bad electrical connection as mentioned. Put your thumb over it diring the day and mess with the reostat.

[89z51l98]

I'll do that... I had wondered what that little window was for... Thanks!

Originally Posted by Moonunit 451

The photocell is at the top left of the left hand or RPM display on the dash on my 86. It's about a 3/8" square open hole. If you cover it in the daylight the dash will dim to whatever you have the reostat from the headlight switch.

After I replaced the dash bulbs I considered covering it cause the dash was SO bright during the day, but I got used to it. The dash defaults to FULL bright during the day. Sounds like a bad photocell or a bad electrical connection as mentioned. Put your thumb over it diring the day and mess with the reostat.

[Moonunit 451]

Originally Posted by 89z51l98

I'll do that... I had wondered what that little window was for... Thanks!

[WhalePirot]

When these cars were new they were complaints about the dash going dim in tunnels and such.