1988 300E OVP?, check engine light/ABS and dash lights out

[Douge]

Hey guys, first, my condolences to Phil, I have not been on the board for some time and Phil was very helpful in many of my prior Mercedes projects and I always appreciated his prompt service and great attitude.

On to my latest car. I bought this car yesterday with 75K on the clock looks like it has about 120K on it now plus or minus. Car runs and drives GREAT. Very minor lump in the idle, and mulitple electrical gremlins. It is showing a check engine light. I tried to retrieve code(s) but the button/led light is just on all the time. I think the protocol is press and release and count the blinks??? Then hold down to clear it???

I pulled the OVP, the fuse is good on top, nothing rattling, and it sits very tightly in the socket. I cannot remember what the box is under the passenger footwell, but it is disconnected. I plugged it back in and the alarm started going off and stayed on even with the car on. I unplugged it again.

The dash lights were working yesterday, but the high mount lamp was broken and showing a bad bulb. I closed that circuit which cleared the idiot light but this morning the dash went dead with the exception of the speedo (mechanical) and the fuel economy guage. I have been trying to pull the binnacle, I thought they just pulled out but this one is not budging.

Thanks for any advice, hope some of this stuff comes back to me, I am sure I have dealt with these issues before just been a good while.

[Gilly]

Not sure on the check engine light, sounds like a CA car and I've had little experience with them and their odd check engine light protocols.

There is a fuse on the back of the cluster which may have blown out. It is red and looks like a bulb socket, you pull that out like a bulb, then you will see a small PCB fuse.

The cluster does pull out using a pair of "hooks". If it is really hesitant, first make sure the dash is warm at least a little, I know some areas of AZ are hot and others are cold, depending on elevation so no real idea what your temps are like. Second, you can mix up a little dish soap in water (in an old spray bottle), and spray that in the gap around the cluster, the little lube action might help free it up so it will pop out.

The box under the passengers shield (plastic panel) is indeed the ATA module, which is why the alarm went off when you connected it, and why it is disconnected.
Gilly

[Douge]

Hi Gilly, thanks, I did get the cluster out and the odometer is now working. I replaced the cluster lights, lubed the dimmer and all is well with the exception of the rest of the instruments. I did see the red socket, in fact I pulled it out (Hey whats this red thing do????)

I just set the cluster back in so I can pull it back out and see if that is in fact blown/bad and how do I assess if it is in fact bad? Its just a little white tab that was protruding from the socket, I guess I should pull the tab out and inspect????? where can I find this fuse????

have a small buzz, sounds like a relay that is on all the time with the exception of when you activate the turn indicators, and then it gets quiet. I did not notice it yesterday so it may not be new, but I dont recall hearing it.

I am getting the intermittent abs light with the check engine. It is a California car, well I bought it here and was told by the "second" owner that it had been bought new here. Is there an easy way to tell? Does it matter? Any other guesses are welcome.

[Gilly]

That small board in there is a pcb (printed circuit board) if it were blown you'd know it, the small printed strip would be blown up sort of, and brown or charred-looking, If it is all intact it is'nt blown and I don't know where to look next, the regular fuses in the fusebox I guess.

If you look at the emission label, it will say something about meeting California Emission Laws. The label is a different color than a "Federal" emission car but I can't remember the different colors off the top of my head, I saw very very few California emission cars in WI, but the laws were even different there about being able to extract codes, not just the emissions themselves, really weird.

[Douge]

I was just going to throw an OVP relay in there being that I was getting both the ABS light and teh CEL. I drove it last night and the CEL went off, ABS light came on, then ABS went out and CEL came back on. Seems when I first start the car and take off I can feel the abs pump for a fraction of a second and when I turn to the right. I will inspect the wheel assembly today and see if its a wheel sensor.

I just dont want to waste $50 on another OVP, it seems I had a similar prob in the past and we all thought it was OVP but it wasnt.

[Douge]

my instrument cluster is now 100 percent.

I replace the OVP which temporarily cleared the check engine light. the check engine light came back on but the code reader is now working properly and is flashing 8x. does anyone know what that refers to?

[Gilly]

Codes:
Fault Code Scanner Mercedes-Benz

If I am reading this right, the problem is with the altitude correction capsule.

[Douge]

Originally Posted by Gilly

Codes:
Fault Code Scanner Mercedes-Benz

If I am reading this right, the problem is with the altitude correction capsule.

Thanks Gilly, LOL I have NEVER heard of that!!! Maybe I could just put it up on jackstands? Where/what is that thing???

[Douge]

Alright, I found it, I will inspect and report back. Of all the blankety blank blanks, lol..... Next thing to go bad will be the basket weave loom defective cross hatch pattern sensor.

Here is what it looks like, it is mounted on the firewall directly behind the battery, attached with a single philips screw. It has a three prong plug and a nipple that looks like it should have a vac hose attached but nothing is attached to it?

I pulled it off and hosed it down with some MAF cleaner, will see if that kills the CEL. I cant even find one for sale. May be a dealer item. Anyone replace one and kill the CEL after replacement?

[Douge]

Just a follow up. I removed the altitude correction capsule. I did not test it, I simply sprayed the socket and connector with electronic contact cleaner and then reattached. I reset the check engine light and drove for about 25 miles without the CEL returning, I went ahead and had it smogged and it did pass and the CEL is still off.

I could not correct the idiot lamp out light. I think I could rewire another light in with the proper resistance but for now I pulled the light from the dash.

Thanks for the help, car runs really well and everything is working!!!

[Gilly]

No prob. Sorry I didn't even see the previous couple posts for some reason, hmmmmm.
The lamp-out light; there are a few tings that often get overlooked.
First of all, if you haven't done this, very systematically start switching things on/activating lights til you have a good idea when the indictator comes on. So start the car, then switch on the headlights, see if it come on. If not, step on the brake, if not that then put it in reverse, and so on, until you are sure of what is setting the idiot light.
A few tips would be the lights on the very sides of the tail lights (side markers) and also the license plate lights often are over looked.
Let me know what you find.
Gilly

[Gilly]

Originally Posted by Douge

Of all the blankety blank blanks, lol..... Next thing to go bad will be the basket weave loom defective cross hatch pattern sensor.

Oh sure, you joke about it now, you don't know what that one costs!
LOL

[Douge]

Gilly, I isolated the bulb and knew it was the high mount. I mentioned in the other thread that I grabbed it to pull the bulb out, the entire housing disentagrated (sun damage) Even the plug for the bulb broke when I tried to disconnect. I just rigged a 12v led in its place. I am guessing the resistance is incorrect and setting the light. No going to fuss with it at this point. All the lights are working.

[Gilly]

If the warning light comes on when you first step on the brake I would agree.

[Douge]

Yep, it came on when I touched the brakes and went out when I closed the circuit on the high mount. I just didnt think to match the resistance when I bought the LED.

Thank you very much for your help on this thread MUCH appreciated!!