instrument cluster light switch & panel light rheostat

I would be surprised if the two position instrument cluster light switch has enough series resistance in the low position to significantly dim LEDs. However, the rheostat is wired as a voltage divider, not a series resistor, and that could dim LEDs. That's why I would replace the light bulb/fiber thing with individual LEDs in the console switches and the heater ideogram if switching the instrument panel to LEDs. Then you could use the dimmer for everything.
Factory lamps (big bulbs) were 158 3.4 watts. There are four of those in the cluster. Do you see a heat, or current draw problem upping those to 5w incandescent bulbs? I’ve pondered low wattage LED’s there, but as you say, the two-position selector switch may be a problem, and I don’t want to get into splicing resistors in and all that.
The smaller 1.2w bulbs aren’t actually noted in the owners manual (unlike the 158’s), and there are NINE of those to replace
 
So yours does not have the fiber optic system?
I don’t know yet - nobody’s commented on the thread I started for instructions on how to get the center console out without breaking stuff :) Suggestions? I count six screws, and no other clues...
 
Factory lamps (big bulbs) were 158 3.4 watts. There are four of those in the cluster. Do you see a heat, or current draw problem upping those to 5w incandescent bulbs? I’ve pondered low wattage LED’s there, but as you say, the two-position selector switch may be a problem, and I don’t want to get into splicing resistors in and all that.
The smaller 1.2w bulbs aren’t actually noted in the owners manual (unlike the 158’s), and there are NINE of those to replace

No you are going from 283mA per bulb to approx 420mA, i’m not going to lose sleep over it ;)
 
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I don’t know yet - nobody’s commented on the thread I started for instructions on how to get the center console out without breaking stuff :) Suggestions? I count six screws, and no other clues...
If you pop a switch out of the console (they pull out), you should be able to see if the fiber is still there. I think it uses 1mm plastic fiber bundles covered by a black plastic jacket. It is attached to the switch with a clear plastic clip on the back. The other end goes to the light source.

I don't recall any secret to removing the console other than taking the already mentioned screws out. I never needed to completely remove mine - just lifted it high enough to access the stuff inside.
 
Factory lamps (big bulbs) were 158 3.4 watts. There are four of those in the cluster. Do you see a heat, or current draw problem upping those to 5w incandescent bulbs? I’ve pondered low wattage LED’s there, but as you say, the two-position selector switch may be a problem, and I don’t want to get into splicing resistors in and all that.
The smaller 1.2w bulbs aren’t actually noted in the owners manual (unlike the 158’s), and there are NINE of those to replace
Replacing the resistor with a higher value would not be hard. I think the voltage dropping resistors for the instrument lights and the blower motor are clipped to the top of the tunnel just behind the console.
 
Replacing the resistor with a higher value would not be hard. I think the voltage dropping resistors for the instrument lights and the blower motor are clipped to the top of the tunnel just behind the console.
Found today at a local store - any use for this purpose?

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@NEG, I've noticed that as well, there seem to be several names for the same bulbs. I've never researched it to know why that is. But I have found that many (most?) listings for new replacements bulbs (standard or LED) like to use the names with the "T" (T5 and T10 in these cases). I assume that might be the 'newest' form of referencing them. So using those in a search like on eBay may offer the most results.
 
The bulb is mounted on the tunnel behind about where the lighter is. It has a metal cover over the bulb with a fiber going to each switch. Check to be sure the socket has a good ground as well as power.
Ok, I finally got the center console cover off. Fiber optic system definitely there, but strangely, there are TWO light bulbs: one at the back of the tunnel where the fiber optic feed seems to begin, and another one which was just loose, behind the lighter, with a bayonet style bulb in it, 4w 12v (and it actually says FIAT on the bulb. lol. their own brand). Fuses seem to check out, connections SEEM in place, but no lumination. I have to check the rheostat I guess. There are directions in the service manual how to do it. The FIAT, bayonet bulb is dead, but the fiber-feed bulb seems good.
And now, I need to learn electricity.

Oh, on a semi-related note: the speedo instrument cluster is currently out for bulb testing and cleaning. Will any harm come to anything if the key is turned for a light check while the cluster is removed, or should that be hooked back up again before activating any electronics?

thanks
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oh, wait a second.....does that SECOND, bayonet bulb that’s hanging loose supposed to go in the OTHER side of the fiber optic feeder? Hmmm. What a fun project this is becoming.
 
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One of the bulbs illuminates the cigarette lighter surround. It is on fuse G along with the fiber illuminator and ideogram bulb for the heater levers.. The lighter is on fuse I.
 
One of the bulbs illuminates the cigarette lighter surround. It is on fuse G along with the fiber illuminator and ideogram bulb for the heater levers.. The lighter is on fuse I.
Yup, read up on that while I was multimetering the fuses. But that bayonet bulb on a string...if it is supposed to be the one illuminating the ciggy surround, it wasn’t attached to anything - just lying on the carpet under the ashtray.
Fuse A is supposed to = 8A, but the previous owner put a 16A in. Checking I, as they may have stuck an 8A in there, But if they did, it’s not blown.
 
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If you pop a switch out of the console (they pull out), you should be able to see if the fiber is still there. I think it uses 1mm plastic fiber bundles covered by a black plastic jacket. It is attached to the switch with a clear plastic clip on the back. The other end goes to the light source.

I don't recall any secret to removing the console other than taking the already mentioned screws out. I never needed to completely remove mine - just lifted it high enough to access the stuff inside.
Ok, did some extensive (including blowing a fuse explosively) electric prodding in the center console wiring nightmare today.

It would appear the button/switch commands have a power source independent of the fibre-optic/cigarette lighter. While it looks like they may be run by different fuses, ALL my fuses checked out with a multimeter.

So why do you think the fiber system / lighter are not getting power? The two bulbs behind the console are good, but do not light, so they must be linked the the same power source. It’s very weird the buttons are all functional though. Is there a hidden resistor, or inline fuse I haven’t found yet?

Edit: page 286 manual shows a inline resistor. It’s tough to get to though. Also, I don’t see a second light bulb in the manual yet.
Although, page 289/290 clearly show TWO resistors, a mystery fuse and what appears to be a connection between the rheostat and the lighter, but no second bulb placement. Anyone?
 
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There should be only one bulb for the fiber system, the bulb goes in one end and the fiber bundle goes in the other.

Is there a ground tab or a ground wire on the bulb holder? The tab would rub against the round canister and the canister would be grounded by its attachment to the body. If a place for a ground wire then it needs a ground wire running to the bulb holder to get light.
 
There should be only one bulb for the fiber system, the bulb goes in one end and the fiber bundle goes in the other.

Is there a ground tab or a ground wire on the bulb holder? The tab would rub against the round canister and the canister would be grounded by its attachment to the body. If a place for a ground wire then it needs a ground wire running to the bulb holder to get light.
on a schematic, is there a common ‘sign’ for a bulb, or light? If I can find both of them on the schematic, that would likely solve the mystery. Maybe a previous owner added it aftermarket for some reason?
 
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