300D Instrument Cluster Lights
 

I have a 1982 300D. I swapped out speedometers over the weekend, and now my dash lights and climate control lights don't work. There is a circular pin connector on the back of the instrument cluster. It looks like I should have 12 volts on the pin that feeds the 3 dash lights, however, I have zero voltage. The bulbs are good, and, when I apply 12 volts directly to the cluster, two of the three lights come on. These are the two that feed the top of the cluster. I can't get the third one, which illuminates the gauges on the left cluster to light. I checked all of my fuses. Any ideas?

The potentiometer is bad.


it's the doo-hickie that you turn to adjsut the brightness of the lights. I don't remember the exact layout, but I imagine that you can bypass it and have the lights work at full strength.


(I had the same problem, I jsut replaced the switch, rather easy in my book)

Thanks!
 

I believe it's called a potentiometer or a rheostat. Actually, the lights started working again. Suspect that the rheostat is going or was lazy after not being used for a while. In any event, thanks for your input!

The rheostat is a joke because with the lights turned all the way up they are still too dim. When I have trouble with one, I just solder a jumper across it to make full bright all the time.

Good luck,

I just had this done on my '83 300D. I wasnt aware that the rheostat controlled the console lights as well. Anyways, my mechanic just jumpered out the rheostat on my cluster and it is nice and bright now.

you can get some bulbs that go in mazdas real bright.

i have seen..
 

Ive seen a kit on ebay with pull hooks and has 5 watt xenon gas bulbs to brighten up the dash.. my 1990 is not as bright as my 1992's but this clown wants 45 bux for this kit.

i wouldnt pay that much and im not in anyway associated with the
seller.. but it is a great idea.. if i could just buy the bulbs he has..

has anyone ever heard or seen these 5watt bulbs he claims to have?? or is he a "hockey Puck" as don rickles would say

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2418159375&category=6763

You don't have to buy from Ebay. His site is here: **************

I agree that his prices are high. Going to try finding those bulbs locally - he can't be the only source.

P.S. Remember that buying from Fastlane and Partsshop above helps support this site!

************** is an awesome outfit.

If you still want to find the bulbs elsewhere, check Ebay:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=42613&item=2424739845

http://cgi6.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewSellersOtherItems&userid=one808hi&include=0&since=-1&sort=3&rows=50

I tried the xenon bulbs and all they seemed to do was make the light bluer and may have melted the plastic that conducts the light from the bulbs to the instruments. The high price for the bulbs is mostly because of the other "junk" he wants to sell with them. That said, he is a decent guy and if you call him directly he will sell you the bulbs alone for much less. Be careful though because after I installed the xenon bulbs it seemed my dash lights got slowly dimmer. After trying the white paint on the prisim trick and jumping the dimmer to no avail I bought a whole new instrument housing on EBay for about $30. When I removed the old one I could see the bulb enclosures had gotten mousy brown from the heat and the clear plastic light "conductors" had melted and bubbled on the ends. My replacement instrument enclosure fixed it and now my lights are much brighter (but still not as bright as on the W124). To be fair, I'm not 100% sure the Xenon bulbs did all the damage but they are the only non standard bulbs I've had in the dash since I bought the car 10 years ago. I'm back to the stock bulbs.

I can tell you that I have had NO PROBLEMS with the bulbs in my dash. I've had tehm in for about 3 months now and still bright as ever.

My experience
 

I used the lights like those in the ************** kit and they helped a great deal.

I also painted the back of the reflecting panel white, i.e. what bounces the light from the prism to the gauges. It had yellowed over time and getting a white surface for the light to reflect off of was also an improvement.

Jim

Has anybody seen any white LED replacement bulbs for this application? I've been wanting to do that as they should be real bright and white.

The bulbs on that kit although look blue are actually White.

FWIW:
The W123 seems to have a weak dash light design and was improved considerably with later models. My W124 is much better than my W123 and they are only two model years different. While I can't be sure about the xenon bulbs causing the melting I got in my W123 instrument panel, there certainly is strong circumstantial evidence that they caused most of it. Those with the W123 chasis may want to be careful drawing conclusions from experiences that people with later cars may have since the setup, while similar, is not identical. My guess is that after 8 or so years of the W123, MBZ realized they had a design weakness in the dash lights and improved the later series cars so as to be less susceptible to heat/melting problems. At least for the W123, I'd recommend you try all the other remedies you can find on this board first before you try the xenon bulbs.