Dash lights?

[Chillidoggy]

My dashboard illumination comes on dim to start with, and after a few minutes decides to brighten up to where I reckon it should be. The rheostat does its job in the up and down brightening but I'm wondering if it might be duff, or perhaps the rheostat module. Everything else works, gauges are OK. Apart from some of the lamps need replacing, which I'll do in due course.

Anyone had this issue before? If so, any thoughts before I go ripping into replacing bits?

[Qavion]

The rheostat appears to be just a variable resistor (wiper arm plus resistance). If you percuss the dimmer knob, do the light levels change (try it when it's dim)?

Have you tried reseating the rheostat module?

 It sounds like something needs to warm up before it starts working properly. This, to me, suggests the electronics are faulty (i.e. the module)

The wiring diagrams show some "centre console lamps" attached to a separate pin on late model car rheostat modules (On earlier cars, they appear to be separate/non-dimmable). Are these also affected?

 

[Chillidoggy]

I haven't tried anything to fix it as yet, but I did see the centre console lamps. Did you see that two of them have '24v 3w' beside them? Not sure where 24v would come from, unless I'm missing something there. Anyway, I wonder if they illuminate the heater controls?

I wonder why the system needs a module to control it?

 

[Qavion]

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Did you see that two of them have '24v 3w' beside them? Not sure where 24v would come from, unless I'm missing something there.

Strange. That's more like aircraft stuff (28volts). Maybe they didn't have 12V ones which fitted.

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I wonder why the system needs a module to control it?

Not sure. I've only seen this in AC systems, not DC. I have seen some fancy electronics in flasher units, but no flashing here (intentionally)

[sanj]

7 hours ago, ian29gte said:

I wonder why the system needs a module to control it?

 

A rheostat capable of handling the required current for all of the dash lighting would be quite large, and get quite hot. This is likely why pre-'90 cars had two dimming rheostats.

[Chillidoggy]

I did have a look for the 3 odd lamps in the parts manual, but couldn't see them. There are four controls for the heater panel, so if that's where they're located, maybe one lamp is for two switches?

Sanj - Any idea what is in that module?