neeillyb

Hey everyone, I have been searching threads for the last couple of hours to see if I can learn anything before I posed this question. I am wondering if it is time to visit a shop for a reset.
A little history. Bought the car from original owner. 127K on the odometer, regular wear and tear, otherwise solid. Roof needed assistance to put it down, found out the relief valve was open. After driving for a few weeks, here is the situation.

Roof no longer works. When I pull up to open the roof, the windows and roll bar go up, then no noises, followed by red flashing (slow) on the toggle.
Try and close the roof, the roll bars go up, as do the windows and the compartment where the roof is stored clicks, and visibly goes down, then repeats itself a couple of times, before a slow flashing toggle occurs.
But wait, that's not it....
The AC works great when the roof is open, nice cold air. When the roof is closed, not so cold, but not hot. All codes check out, plenty of freon, temps all good, no CEL.
Radio never goes off, unless I turn it off. No steering wheel buttons work for radio, but do for all else.
Car won't unlock using the interior unlock button, unless I open the door, then close it, and then it will lock or unlock it. Key fob works fine.
Alarm system fuse #6 blows as soon as you replace it, so I left it out. Checked all the grounds, everything looks good. Puzzling.

I think I have listed all I can think of. No CEL, no malfunctions, and car drives like a dream. Seems to be a gremlin or two in the electronics and I am seeking some help.
Can I hard reset the ECM to factory and see if the system re-learns itself? Can I do that, or do I need a scanner or a shop to just do it? Is there a decent service manual I can buy? Lots of online electronic options for a reasonable price.
I have scan tools for my domestics and have no limitations on my mechanical ability and my shop is kick a$$ after years of collecting tools.
I am just puzzled at this point and could use any hints, tips, tricks or whatever anyone can throw at me. Would like to solve it, cause it's the kind of thing that keeps me up at night!

Thanks for the help everyone.

andy_breuer

It sounds like you are learning well about the W208! But I’d just like to start with clarifying an important thing about this car and most cars on the market today.

The ECM runs the engine and ONLY the engine and errors in that system give you a CEL. All other systems have a separate module and problems with any separate model CANNOT effect engine operation.

The AC has a separate module
The top has a separate module
The seats have a separate module
The steering controls have a separate module
…and there are others, but you get the point.

The benefit is that safe engine operation is ensured.

So for each of your gremlins you will need to understand which system, module, and its requisite separate module is involved.

andy_breuer

Now, to start with the AC. Freon naturally leaks from all AC systems and needs to be added back in over time. I ended up adding 3 - 12 oz cans before my AC operated effectively. You should start there, just make sure after every add the pressure settles down into the green/yellow range.

Can you run diagnostic on the AC when it isn’t working (top down) and report back values 1-24?

andy_breuer

And now for the top operation:

1) make sure the retracting cover inside the trunk area is closed. It has a switch that stops the operation for safety reasons. Is it closed and latched?

2) check the oil level in your pump, is it ok?

neeillyb

Thanks Andy,
Did diagnostics with top open (down) and closed (up), car running about 5-8 mins.
Top Open were as follows
Diagnostic Codes Was same for both top open and closed (duh)
B1419 (clutch) and B1416 (Coolant Circulation Pump)
Sensor Value Test Codes Top Open

1. 261 20. 0
2. 94 21. 7
3. 90 22. 0
4. 90 23. 0
5. 87 24. 13.7
6. 165 40. 8
7. 8 41. 5
8. 90 42. 248
9. 8 43. 14
10. 6.0

Sensor Values, Top Closed

1. 91 20. 0
2. 98 21. 6
3. 90 22. 0
4. 90 23. 0
5. 90 24. 13.8
6. 180 40. 8
7. 9 41. 5
8. 92 42. 248
9. 8 43. 14
10. 3.3

In all circumstances, looking under the hood, the clutch is not engaging at all, even if toggling the EC button on/off.
Cleared Diagnostic codes, and they came back.

Based on Diagnostic codes and info, it would appear that maybe I start with the clutch, or look at the wiring to it (all fuses are good), check grounds and replace if necessary, then top up Freon. Would the circulation pump have actually failed or has the clutch failure prompted the circulation pump code, or vice versa.

So many questions, but narrowing it down.

Thanks.

neeillyb

So tackling the top operation, the retracting cover is currently out of the car, but the switch is taped down (for diagnostic purposes)
Oil level is within the lines and has stayed that way for a month after I topped it up. Previous owner had the drain plug loose and the relief valve wide open, so it leaked. I have been using the roll bars, and no issues, working fine and no leaks visible.

andy_breuer

For the AC with the top down, value #1 is for in car temperature sensor and you indicate as 261 degrees. That sensor is measuring normal temperatures with the top up.

You in-car temperature sensor is showing bad data and is likely bad, and is being effected by the convertible top position. I would try replacing that part first.

Andy

andy_breuer

For the convertible, since your headrests work, the pump is definitely functioning, which is good!

1) remove the rear seat, it’s easy and requires no tools. Is there any oil pooled there?

The internal seals of some of the actuators can go bad and all fluid to pass by and then it generally pools under the seat.

neeillyb

I have the back panel in the trunk out with full access. I have been watching for leaks (none) and checking the various pistons and mechanisms for leaks, and there is very minimal seepage, and the hydraulic pump fluid level has remained stable. It's a puzzling little critter, but the complicated nature of it is intriguing.

I will shoot for replacing that temp sensor, seems easy enough.

neeillyb

WEEKEND UPDATE
I had some time to chase the AC issue this weekend. Amazing what happens to an older vehicle when it sits in a garage unused for years. Pulled all the wires, cleaned contacts with some Emory cloth, electronic cleaner, added some dielectric grease, and also tackled as many grounds as I could find to clean up as well. I cleared the codes on the HVAC, hooked up a recharge kit (needed barely a squirt) and now everything is functioning as it should with cold, cold air! Of course this morning was a beautiful 63 degrees here, so no need for air, but it works!

I also had some time to dive into the soft top. All the hydraulics are solid, no leaks at the pump, lines all good, slight seepage around the cylinders, but nothing that concerns me right now. Just need to figure out why it does what it does and why it's not doing what it is supposed to be doing.

andy_breuer

Take a look at the thread here, which goes in depth to diagnosing the micro switches:

https://mbworld.org/forums/clk-class...ailures-3.html