1998 E300 TurboDiesel ACC Display Illumination Problem

This morning while driving to work, I noticed that the Automatic Climate Control display is no longer illuminating when the lights are turned on. All the individual indicators appear to be working and the small red lights (Auto, EC) are working, but the main panel does not backlight when the lights are on. Is there a fuse which controls this and if so, where is it?

[98E300man]

I have the same problem....but it is intermittent. If I tap firmly to the left of the ACC, I can restore the illumination.

I would like to get this fixed permanently....what would be the best way to do this. I hesitate taking the car to the dealer with an intermittent problem.

I will try the tapping solution. I have found this worked when my right front headlight was out. To me, this is disappointing. I should not have to bang on the console to keep it lit.

[Rick Miley]

Now that you've mentioned it, I have spoken to the dealer about this. The service writer told me that the bulb gets loose in the carrier and replacement fixes the problem. Then he quoted me an hour's labor to do it. Now, if this was a W124 where you have to remove a bunch of stuff to get to the module, then I might buy it. But the whole control box slips out using the radio keys. This operation shouldn't take any more than 5 minutes! So I bought the radio keys, but the thing started acting right so I never bothered checking any further. Once in a blue moon the panel stays dark, but a tap will light it up. If I get time tonight, I'll get out the radio keys and do some more investigation.

Rick,

What did you pay for the radio keys and do you have instructions for removing the control box?

[Rick Miley]

I knew as soon as I wrote that post that somebody would ask what the radio keys cost. It's been over a year and I had them added on the invoice with other stuff, so I honestly don't remember. But I can't imagine them being more than $10. As for instructions - no I don't have any. Shouldn't be any more complicated than insert the keys and pull the unit out.

[Rick Miley]

Here they are for $12.50. PartsShop

[DR.DIESEL]

The bulb in the A/C head unit only takes a few minutes to change. You just need MB radio keys to remove it.
Here at my "Stealership" we charge around half an hour which
includes hooking up a diagnostic computer to erase the CAN codes that appear when the ACC head is disconnected even with the key off.
Have fun
DR.D

[Rick Miley]

Dr. Diesel, thanks for that tidbit. Are you trying to tell us that this is not a DIY job? What ill effects will we suffer by pulling the head unit? Are the codes simply stored in the memory, or will stuff cease to function? I was planning to dig in to this tonight.

I hope you can understand why I was torqued when the service writer quoted me $70 to change a light bulb and expected me to simply hand over the money without asking questions.

Edit - Spannman, if you're driving to work in the dark, you're going in too early. Stay home until we can get this figured out.

Once again, this forum has come through for me. A good rap on the left side of the control box did the trick. However, I would be interested in what Dr. Diesel has to say to Rick's question.

As for the work thing, I leave the house every day at 04:30 for my 65 mile commute into D.C. At least I do it in style.

Thanks again for the help.

[jcyuhn]

Would you get the code set if the battery was disconnected when the ACC panel was pulled? A bit more work, but paying for such a simple task is really annoying!

- JimY

[DR.DIESEL]

These codes are harmless and will effect nothing. Our policy is to
leave no corupt info behind in the unlikely event of a future a/c fault. Then if we begin to diagnose, any codes that are stored are
genuine and not a result from previous repairs.
For the DIY'ers, if you have a a/c fault later down the road, just tell the service writer that the a/c head was unplugged so the tech does'nt start going in the wrong direction with testing.
DR.D

[Rick Miley]

Does anyone need more info on this? I haven't forgotten about it, but my car has been at the dealership for two days getting the Air Mass Sensor replaced.

If you want a picture of the climate control unit, I can probably do it this weekend. But you need to get the radio keys to get it out anyway.

Rick,

I am not planning on digging into mine unless absolutely necessary.