I have posted about this before, but no one seemed to really have idea about repair.

Problems started about 2 months ago. Driving along enjoying the silence of S-500 and all lights on right side of dash come on (ABS/ASR/Brake/Check Engine) as well as speedometer goes to 0 (I was going 75 MPH) and the yellow triangle in the speedometer comes on. Car continued to drive - but power steering cut out. 30 seconds later, all lights go out and car goes back to normal.

Next day. Stopped at light. Same thing happens - but this time, the transmission will not shift up. Engine revs to 4,000 RPM - no upshift. $$$$$$$ run through my mind. Then, lights go out and all back to normal. Almost like car goes into limp mode.

Day 3 - take to mechanic. Diagnosis of new Transmission Control Module. Neat.

Day 4 - pick up car. Make it through 12 hours. Same symptoms. Many explicatives later....back to mechanic.

Day 5 - new transmission control plate.

Day 6 - pick up car. Perfect for about 1 week or so. Then same symptoms. Take back to mechanic.

In the meantime, the battery light comes on and yellow lights on fuel gage begin blinking...so new alternator and some kind of check valve/cannister thing.

Return to mechanic for above as well as contiued problems with lights. New ESP/ASR control module. Now same symptoms again! But they are more frequent and last longer - used to be that the car would "reset" in a 45 seconds or so - now it takes several minutes.

This has been an expensive expedition to get no where....any thoughts on what could be causing this? Car only has 45,000 miles on it. Understand the 140s can be somewhat difficult - but damn!

Was there ever any diagnostics done? Any codes read?

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Well, actually W140s will work with you if you do read all codes carefully. There are two typical readings of codes: a short 15 minute express check up and a comprehensive almost 2-hour system diagnosis.

Most independents don't like to do the long test (to time consuming), but according to your symptoms, I would take the car to the dealer and have the full test done before changing every single accessory on your car.

If there are NO significant codes, then I would begin to worry, since the task becomes real difficult. It could be a short somewhere, a reversed connector or something really small that codes will not detect but will make your car misbehave such as bad as you describe.

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A. Rosich
CL 500, 1998
S 500 L, 1998
E 320 T, 1995 [Sadly sold ]

I may be out on a limb here, but I would have to assume that there was diagnosis done in order to arrive at new modules, etc.
I don't know what type of diagnosis was done (short or in-depth) but there must have been something.
Has anyone else had this type of problem? What was the fix?

The trans can go "limp home" for a huge number of reasons. Lack of speed signal from the traction control is one, improper shifter inputs one, alternator voltage too high or low, CAN issues another, tires the wrong size another. But, the point is that diagnostics produce results or guesses. Intermittants don't leave much to test, but they do leave codes. There must have been codes to throw the parts that have been thrown, what were they?

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

It is next to impossible to come up with a solution or even a guess on a problem as originally described without any codes to guide the members.

The W140 is incredibly complex, and that is why is also very peculiar about providing fault codes (even on intermittent failures) to provide assistance on a solution.

__________________
A. Rosich
CL 500, 1998
S 500 L, 1998
E 320 T, 1995 [Sadly sold ]

There are no codes to read.
Any ideas on where to start with this problem?
We have started looking in the wiring for bad "z" connectors/joints.
Any thoughts would be appreciated!

LOL . . . a Mercedes w/o codes. . . just doesn't happen. . . LOL!

The 'bad-battery' or altenator going bad (ie, low voltage) can cause what you're experiencing.

But first, read the codes . .

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

There are not any codes......I swear!
Alternator is new.......battery seems to be good.

I have to ask: Are we talking about the same types of codes here? Not the OBD2 codes from the connector under the dash, but from Star Diagnostics, big connector in the engine compartment in front of the module case.

Based on my experiences with my 140, I have a hard time believing that there are no codes set.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

To me it sounds like you're getting bad electrons from that new alternator or your wiring harness is shot. There are just too many other things going wrong.

Jim F is right too. W140s will always show a code. With as many failures as you have that sucker should be lit up like a Christmas tree.

Where have you tried pulling the codes from? OBD-II? The diagnostic port under the hood (the blinkey light)? Star Diagnostics?

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"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles