jinark

Well, turns out I didn't solve it. Here is all the odd things the car is doing.


Ignition off, turn on lights. There is a large tubular black thing under the plastic engine cover on the air intake side that clicks when the lights are turned on. Followed by a faint buzz from the left bank of coils.


Turn on the lights and insert the key and it won't turn. Turn off the lights and it turns and the car starts normally.


If you leave the key in position 1 and turn on the lights the license plate lights come on faintly. If I then start the car the license plate lights go out.


The tell tail for the rear fog light, that little round orange light near the light switch, comes on anytime I turn on the lights, even if I do not pull the switch out to the second detent to turn the rear fog light on. With the ignition off the rear fog light lights up very faintly, start the car and it goes out when it should be on.


Leave the lights on after shutting the ignition off and the warning lights on the instrument display start flashing randomly, along with the climate control and radio displays. This is accompanied by lots of clicking in the dash like relays being activated. If I step on the brakes while this is going on all that flashing and clicking stops. Also if the trunk lid was open when this goes on the trunk light is flashing. If I pull out the trunk light switch plunger to shut off the light or push it in like the trunk lid has been closed the flashing and clicking stops.


Sometimes when I open the trunk with everything else off the trunk light pulsates and there is an irregular clicking from the area behind the trunk liner behind the CD changer. There are some electrical items back there but I have no idea what they are.


The reverse lights have quit.


If I turn the ignition to run and put on the turn signals I can remove the fuse that is suppose to feed the turn signals and the signals continue to function without the fuse being in it's slot.


Everything else seems to be working normally. I've given up and taken the car to the MB dealer but they haven't started on it yet.


Any suggestions would be appreciated.

jinark

The dealer tracked down the problems, A brake light switch had gone bad so it was replaced. and the ground wire in the harness that goes to the deck lid lights had broken, I guess from the normal opening and closing the deck lid. They also replaced some rear bulbs with whatever MB is using today.


Hopefully this will be of value to someone else who may have similar problems with their car.

Serndipity

jinark.......thank you for providing the followup.

The brake light switch has been a very common problem on older MB models. The switch has two separate switched circuits, one for the brake lights the other for the ABS/BAS circuits, with the later usually triggering the dashboard ABS/BAS fault. MB designed the switch, DIY replacement is easy, has been covered in the forums numerous times and it's only a $20 part.

Last year I experienced similar perplexing symptoms as you described.

In my case, it started with an occasional lamp out warning upon braking, until one day, after closing the trunk, the lamp out warning always triggered when braking.

Found that none of the lamps located on the trunk lid to be working (e.g. backup, 3rd brake light, rear fog, license plate etc.). With the car turned off, opening the truck operated the passenger side mirror and then the electrical radiator cooling fan at full speed. If I opened trunk while the engine was running, the dash also lit up and flashed like a Xmas tree. Closing the trunk or holding in the trunk's courtesy lamp plunger, stopped the ill effects.

The reason for the strange interactions with other systems is that, to save on cost and weight, communication between the numerous vehicle control modules is via the CANBus, with voltage encoding. This allows the various voltage levels on fewer wires to create channels, to control/operate numerous devices. To make a long story short, when a broken or short circuited wire (e.g. especially a ground return), occurs, the channels may no longer be totally isolated from one another.

During my troubleshooting and repair, I found the thick brown wire (e.g. primary ground return from the trunk lid) inside the trunk hinge wiring harness broken. Not sure about coupe models, but on the cabriolets, the harness is on the passenger side, between the trunk lid and the quarter panel.

The reason that the breakage of this wire, is that it's construction is of only a few strands of large gauge wires, which makes it much more susceptible to breakage upon flexing, vs. had it been made of more strands of smaller gauge been used.

For that reason, I cut out all of the stiff large brown wire from inside the rubber flexible sleeve and replaced it with a much more flexible wire of the same gauge.

jinark

Thanks Serndipity.


I sure wish you had posted all that before I took the car to the dealer though. Older cars I can fix easily (just restored an E-type), newer cars with the multiplex wiring can be a real pain, but if pointed in the right direction I'm sure I could manage.

Serndipity

jinark, I take it that you're a new A208 owner.

Congratulations, the W208 (coupes, built until 2002) and A208 (cabriolets,built until 2003), mechanically have proven to be bullet proof. Not to mention timeless design and being a head turner.

Fortunately, you did not purchase an example of the next CLK W209 generation, which incurred numerous production problems, all very expensive to repair (e.g. failing balance shaft gears/cam shaft senors/faulty radiator radiators mixing coolant with transmission fluid).

As a result, now approaching 17 years of ownership, I'm still here. The only issues have been in the electricals (e.g, MAF, CPS), but as an avid DIYer, repaired for next to nothing.

That said, older MB models do depreciate greatly after the warranty expires....because of the cost of repairs and maintenance.

If recently purchased, you got a great bargain (e.g. 5 to as much as 10 percent of MSRP)!

Unfortunately,as time passes, the fabled German engineering has been vanishing.

With represent to the W208.......

Our owner's manuals, state that the transmission has a life time fill and never needs servicing. That was until, transmissions starting failing (e.g. traced to wear from the graphite clutches and/or other wear deposits. The MB engineers were so, that they discovered a miracle fluid, they not longer not provides for a drain bolt on the torque converter. Since then, MB has since recommended regular transmission service, each and every 39,000 miles.

There are no brake pad wear senors on our W208s.

In some way, I get it......your MB dealer service department will monitor and advise at $$$$$.

Lastly, as an cabriolet owner, at the same time, given German engineering, in excess, at some time your power roof operation will fail (e.g. not a question of if, but when).

Thankfully most of the A208 power roof problems / repairs have been well documented on the MB owner forums.

jinark

Thanks for your thoughts.


We've had the car for 3 years and 25,000 miles. It's our road trip car of choice. You want to see someplace like Yellowstone you can't beat a convertible.


I don't post here much because the car has really been pretty bulletproof except for this last electrical issue.


I only take a car to the dealer if it's something I'm stumped on or know I can't do or don't feel like doing, or don't have the equipment (like front end alignment).


I replaced the shocks and steering stabilizer just after I bought it. It was always serviced by a MB dealer and it was low mileage (9,000 miles a year) so it's in excellent shape.


I also repaired the time and gear display when it decided to virtually quit working.


Last year I enjoyed the thrill of disassembling the back half of the car to flush the system and add hydraulic fluid, no visible leaks in the usual places so I simply monitor and listen for tell tale sounds of hydraulic pump cavitation. As you correctly point out info on this forum was an invaluable resource for that task.


Earlier this month I had to repair the stop on the left side rear seat power window. As happens, the plastic piece that attached to the Metal "L" bracket fell apart so the window was going up too far and too far forward. I fabricated a new plastic piece out of nylon stock I had laying around and pop riveted it to the bracket. It's more robust than the original


I'll be replacing the brake pads next month.


The Ford Dealer Where I bought the car sent it to the MB dealer for a "B" service just before I came along so I've done 1 subsequent "A" and "B" myself.


My only gripes about the car are the Rube Goldberg cup holders, the CD changer in the trunk and, until I installed one, no MP3 input for the radio.

Serndipity

So far, other then basic PM, I've had very few issues.

In regard to the power roof, of the 8 hydraulic cylinders, the rear bow and/or case cover lock cylinders tend to leak on the A208 first. The seals MB used have a service life of about 10 years. Thankfully, one of the forum sponsors, Top Hydraulics, can rebuild them for reasonable $. This seems to be mostly related to being in a warm climate. Knock on wood, it still works flawlessly after 17 years.

As in the trunk lid wiring harness wiring, occasionally a broken wire has occurred in the soft top case cover too.

Also, in regard to the cup holders, your 2003 came with a spill resistant transmission shift control module under the center console (e.g. installed as standard, from April 2001 on).

Lastly, as PM, I replaced my idler pulley (a.k.a guide pulley) in my serpentine belt system. Another great example of current German engineering. As the smallest pulley in the system (e.g. spins the fastest) and is constructed with single bearing / plastic body. A new pulley is only a $10 part and a snap replace on the CLK 320, M112. When I replaced mine at 85,000 miles, I found 3 fracture cracks beginning. It's not something you want to occur within the serpentine belt system (e.g. loss of alternator, power steering, water pump etc.).

Joseph Mullins

I'd like to thank Jinark for this post. This had driven me crazy for years--the clicking and dash crazyness...and it was just a broken ground wire in the trunk harness. I think in the interim it ruined my HVAC head unit, which no longer activates the a/c compressor and the red LED lights no longer work ;/. Now that this issue is fixed i can move on to the next!