Jackieclk

My wife's CLK W 133,000 miles suddenly will not maintain cruise control function. Just yesterday the cruise started cutting off on uphill grades. Today it will not engage for more than a second or two, even on a downhill. Anyone have any experience w this or ideas? Thx.

shadenfroh

Do your brake lights work and work consistently? Have you ever had problems with ABS/ESP?

I'm no expert, but I'd start by replacing the brake light switch, even if it's just for peace of mind - it's 25 bucks / .5 hour job and the little sucker causes trouble with all kinds of systems.

Jackieclk

Thanks. The brake lights do work. The ABS/ESP did come on and off a few times a few months ago (2000 or 3000 miles ago). I did not take it in for service because the alert went away. Since then I had it aligned, new tires in front then had an accident where I was hit in the drivers side rear wheel which bent the control arm which knocked out the alignment. That control arm had to be replaced and the car was realigned. Seemed to run fine for about 500 highway curies control miles until suddenly the cruise cut out on the uphills. Now it won't set except at below 60 MPH and then it cuts out on the uphills again.

shadenfroh

The relay that controls the ABS/ESP pump gets stuck sometimes and the warning lights come on only to come off a bit later. In this case the pump continues to work overtime and wear out. They've updated the relays so there's a new part number.

I have other ideas, but will refrain from sharing them. I'm not a mechanic and can only give you advice based on my extensive reading and modest experience. I like working on my car, but the brake system is off-limits for me. As soon as I get the slightest suspicion that something's off, it's a visit to my mechanic.

Get it scanned soon. The braking/steering/stability systems are rather simple, but being dependant on each other makes diagnosing problems difficult for folks like us. Any shop with a STAR will make the car sing like a bird and 15 minutes later you'll know where you stand.

Keep us posted.

Jackieclk

Just got to Denver last night, will be here for a week so I do have time but don't have a shop to work with. What is STAR? Want to avoid the MB dealer if possible (they always make me feel guilty for not doing everything they recommend and they always recommend plenty to do)

shadenfroh

It's the diagnostic tool for Mercedes Benz. You can use google to find a shop that has one. Any shop or the dealer will do, doesn't really matter, you'd just be asking them to run a scan, print the results and consult you on the possible repairs.

chriscarter

I have a similar issue on a 2002 CLK320. Brake lights remain on, although switch is functioning properly. Checking voltage at switch connector, I have 12V between the terminals when disconnected from switch. Only one should be hot, with the switch completing the circuit to ground and turning on the lights.


With the lights on always, the cruise won't set, and I get recurring ABS, ESP, and BAS error lights on the dash. I'm guessing I'm getting voltage feedback through the ABS or cruise subsystems. Will continue to search for issue, though if anyone can shed some light based on these symptoms, I'd appreciate it.

Jackieclk

I am afraid I can't be any help here. I know i did not have the same problem as my brake lights only came on if the peddle was pushed. Since we are traveling I just took my CLK to a local foreign car shop and they are working on it. I'll post the outcome on that when they are done as it maybe useful to others.

MJ50

moved to W208 forum...

Just Is

Not a mechanic, just speaking from experience:

Had the same issue and it ended up being the transmission control unit. Other symptoms included: stuttering or incredibly reduced power during wide open throttle. IF you haven't punched the gas in a while you probably wouldn't even have noticed anything is wrong.

The TCU is located in passenger side footwell. If you pull back the carpet you'll find a white metal plate. You should see a couple screws near each corner of the plate securing it. If you remove those and gently move it around youll see a bunch of wires connected to the computers that are mounted to the back of the plate. If those wires are wet and oily, i am willing to bet thats your problem. The O rings where the wires connect to the trans went bad and allowed trans fluid to creep up the wires and into the TCU, thus ruining your TCU.

VERY Important Notes:

Under no circumstances should you attempt to use a 01-02 CLK's TCU for your 1998-2000. Sometime in 2000 Mercedes switched from ME 2.0 to ME 2.8. If you plug a TCU intended for the 2.8 into your ME2.0 car, it is my understanding that the ECU and other computers will turn into paperweights.

Make sure you are getting the correct part by comparing the part number on the sticker of your broken TCU.

Before you bother with any of this, you MUST clean the wires all the way down to the trans AND replace the bad O ring. Otherwise the oil will creep back up and foul up your replacement TCU as well. Ask me how I know...

I advise keeping the old TCU as well. Clean the wires and plug the old TCU back in. Use it for a few days and then recheck your wires/TCU connection. If there is once again oil on the TCU connections, you need to do more cleaning and verify there is no more oil on the wires.

This is still a work in progress on my own car. Good luck.