Lights around the HVAC controls don't illuminate

[Hogzip]

I've got an '81 528i I am restoring. Current focus - the heater controls (left hand selector - AC and amount of heat; center - fan speed, and right - where the air/heat is directed) are usually not illuminating. So when I'm operating the HVAC when it's dark outside, I can't see the controls. Every once in a while a light or two comes on, but then goes out again.

In looking at the parts schematic, there are a bunch of "prisma" - a different one for each of several words - "cold", "warm", "normal", etc. Most of them are no longer available. What are these - little lights, or just see through lenses?

Enough of trying to ask the perfect questions - how do I get these lights to work? What parts would I need, and where could I get them?

Thanks guys,
Brian

[lazytv]

Can you post a picture?

Have you looked at http://realoen.com to see if they are still available?

[T.Hanson]

A photo, otherwise I'm nuts. My '79 and '81 in twenty years, I've never seen any light or little teeny lights illuminating the three dials. None indicated on the realoem.com heater control exploded parts view either.

Are you actually looking at bulbs of some kind, somewhere ?

[Mike W.]

Yep, I remember the bulbs in there. Almost all of them were burned out when I got my first E12 back around '92. Replace them all, not just the ones that are burned out. #20 in the diagram. Dealer price looks a little expensive, you might be able to save a few bucks on line. IIRC I bought mine at Radio Shack when they still sold a few parts.

http://www.realoem.com/bmw/enUS/showpar ... Id=64_0457

[lazytv]

The are colored jewels with a mini wedge bulb behind each one. Look on ebay for 'sylvania bulb 2721' they were used in bmws, minis, saabs, vws etc.

http://www.sylvania.com/en-us/applicati ... px#fldYear

[T.Hanson]

No big problem admitting I'm nuts. At least Mike W. canceled my bogus opinion since I'd never seen any lights there were none.

Have we noticed there are more than a few, "Expert," problem solvers on the various boards, when you try to use their advice, it's obvious they don't know the positive from negative battery posts,...etc.

I guess I admire anyone who is so motivated to restore an E12 to absolute new specs. Their patience, willingness to learn, tenacity. Yet after my (post) trying to get the heater blower ring to function, being saved by replacing the fuse,...

Taking the entire center panel out, contemplating the potential horrors listed in the replies to replace bulbs I never missed, insist I could see the dials even in the dark to adjust them,...

I give up.

[Mike W.]

Eh, you're not nuts. You just have a less than perfect memory. As do I, I thought I remembered but I did check Realoem just to make sure.

[PeterD]

Great question, my car has about half the lights working and I'm trying to fix them all as well. How many bulbs are there in total? Is the analog clock supposed to be illuminated as well?

[Lenny D.]

2¢ in the trying to keep it stock/working dept. . . mine have always worked.

There are two (miniature) bulbs total for the 'center' dash that (dimly) illuminate with that classic BMW orange glow the controls for the vent, A/C, and heater controls. The analog clock has its own bulb (and must be integrated into the existing wiring if the analog clock is a retrofit to '80 and later).

I would post a pic of where they are located but it is nearly impossible to do when they are installed in their teeny holes in the dash cluster.

The bulbs are simply pushed into a socket at the end of a 2 wire lead that friction fit into the holes behind the center cluster. There is one for each side. I get to them through the center vent on top of the dash. If you look at the center cluster straight on, the holes are located (behind the cluster, of course, you can't see them from the outside) at 10:00 and 2:00 orientation relative to the round clock, analog or digital. There is a solid area of plastic on the cluster face where these holes are located. Mike's post of Real OEM pic shows number 5, and the orientation of what I'm trying to describe. Getting one's hand in there through the vent opening (removed, of course) and holding that tiny wire lead with the socket and bulb, then sticking it in the hole is FUN!

Remember, you wanted light. Expect them to be extremely dim and will only glow with illumination in the darkest of driving experiences. Oh, and of course, they don't necessarily want to stay in the holes, you have to orient the wire's tension to 'keep' them in there.

But, hey, it's all part of the battle to keep 'em going!

Oh, and I think the miniature bulbs may be available at one of the bigger auto box stores. I have purchased them there in the past. When I find them, I usually stock up with some spares, just in case...the good part is once replaced those bulbs may outlive some of us

[Robert Bondi]

In looking at the parts schematic, there are a bunch of "prisma" - a different one for each of several words - "cold", "warm", "normal", etc. Most of them are no longer available. What are these - little lights, or just see through lenses?

Thanks guys,
Brian

The prisma likely refers to clear plastic pieces that funnel light from the little peanut bulbs to the spots that illuminate on the dials. They are basically inexpensive prisms. Light enters one end and some light comes out the other side... with a lot of loss inbetween. Even after replacing the bulbs, you might be surprised at how dim some of them can be.

I believe the idea behind the design is to use just a few bulbs to light up many locations by using the plastic prisma to distribute light. LEDs do that job on modern displays.

[Hogzip]

I had my local Chicago old BMW guru look at it. Lenny D (above) is right - two small, trying-to-be-hard-working bulbs.

Thanks to all for your thoughts.

[RonDwyer]

I'd replace the bulbs and check the connections to the bulb holders. Bad filaments and intermittent bad grounds are common.