FairfaxC32

A mechanic pointed out to me that my "Check Engine Light" won't come on. After removing the odometer gauge cluster, it is obvious someone removed the LED for the check engine, as well as one for a symbol that looks like a cloud of smoke. I bought the car used from a private party, and I'm pretty pissed that someone went to the extent of removing the soldered LEDs (and disposing of them) instead of fixing the freakin' air pump. Idiots. I took my gauge cluster to a MB dealership this morning, and they are so inexperienced with these that they didn't even know how to open it up to get to the LEDs. Yikes. Service manager said when there's something wrong with these clusters, they replace the whole dang thing, and they can't order just the LEDs. Does anyone know where I can purchase these, and what the voltage/amperage is on these so I might be able to substitute a Radio Shack LED instead? Thanks.

MarcusF

Virginia is a long ways from California, but -

In California, the seller is responsible for supplying a VALID smog certificate. The smog techs are not allowed to pass a car unless car has a working check engine light AND that light is NOT illuminated. In your case, if you bought the car in that condition, the smog cert was illegally obtained. The California DMV loves to hear about crooked smog stations and the car owners that use them. I wonder what the Virginia DMV thinks . . . . .

wingless

These can be purchased on-line. The two big distributors are Digi-Key or Mouser. The size and color need to be selected. The part is polarized, meaning that it works in only one orientation. Hopefully the assembly will have a silkscreen with the cathode marked with a band.

Post a close-up image, with a scale or ruler, to enable additional assistance.

It is possible to use a hand-solder iron and wire solder to replace this part.

FairfaxC32

I've bought/sold several cars in virginia and I haven't heard of sucha law here. Not a bad idea, as it's an extra protection for the buyer.

So I found that the voltage across the check engine light connections was just under 5 Volts, so I installed a 5V LED from Radio Shack and it works fine. Of course, now the Check Engine light won't go off, because it's still throwing the P0160 (if I remember correctly) error code regarding the secondary injection system malfunction. Replacing the air pump tomorrow...

FairfaxC32

The cluster's already sealed back up and in the car, but I did take a picture (without the ruler), and it's attached to this post. The red circle shows the LED from Radio Shack, and the green LED shows what the original LED probably looked like. The green circled LED is roughly 0.125" width.

wingless

Thanks for the image. It sounds like the wrong LED is working okay. Is a replacement part number required?

Please note that in addition to removing the LED, a resistor was also removed, below and to the left of the new LED.

FairfaxC32

I couldn't see any P/N on any of the LEDs

Why would someone remove a resistor? WTF.

amdeutsch

Because it is used for current limiting. Without it it may draw too much.

wingless

Is a part number required to permit replacement of the missing LED with an appropriate replacement part?

It may be that the resistor removal was an attempt to "silence" the LED. My guess is that the CEL LED may activated from two sources, each with their own path through these resistors. The path through the remaining resistor is currently active. With that resistor missing the other path will not function.

FairfaxC32

What are the chances of the missing resistor being the same resistance as the one that's still there? I can measure the Ohms of the one still there, and get something close from radio shack. I still am shocked and disgusted someone would disable the electronics instead of fixing the f'ing problem...

wingless

Yes, replace the missing resistor with the same value as the existing part.

benzmodz

A long while ago someone in Germany (??) replaced all of the LED in his car with blue ones. Including airbag, stalk and door switches. He put up a parts list and a cross-reference on which type were used in which location.

The only way to get info on the resistor is to look at another cluster. I would assume it is a voltage resistance for LED operation. But who knows, maybe it was never there in the first place because it may be a C230 or diesel thing.


The whole thing snaps together .... why did the dealer refuse to do that ?

wingless

Yes, it is possibly a configuration resistor, to permit PCB usage in several vehicles. If the existing resistor is 0 ohms, then that would be very likely.

The missing resistor has flux around the pads. The other solder joints have been cleaned, so something was there that has been removed. If done by a MB contractor, not a hack, then they would have cleaned the flux.

That is unlike the empty LED pad to the left of the new LED. That pad has never been used.

Yes, examination of an identical cluster would be best, any chance of that?

Examination of an image of a larger section of the cluster would not hurt.

FairfaxC32

They said they don't deal with repairing the cluster - if there's something wrong with it, they replace the whole cluster. Not very efficient, especially for a $3 LED. I told them if it was still under warranty I would be happy to have them replace the whole cluster...