1995 w124 300d cruise control

[polarisrmk]

I have a 1995 300 diesel with a cruise control problem. With it set it will suddenly turn the cruise contol off and a few min later it will turn back on by itself. sometimes the cruise control will not even work. Ideas?

[oldiesel]

The usual culprit is the cruise control amplifier,i am not familiar with the 1995 but on both my cars an 87 and a 91 that part is located just about ahead of your left knee. You have to drop the lower dash to see it,not that seeing it is any use! There is an online troubleshooting guide at http://gdl-online.com that may help you. I recently gave up on the original system in my 87 and installed a Rostra aftermarket unit that is working very well for about $180 which is less than the cost of the reconditioned amplifier from GDL i think. Don

[Jeremy5848]

Resoldering the circuit board that lives in an aluminum box under the dash (as Oldiesel says) may fix the problem. I have done that operation twice and it was successful both times. A tedious job but an inexpensive fix if it works.

Keep in mind that many commercial rebuilders won't accept for core credit a board that has been resoldered. The aftermarket unit might be the way to go (I've never seen one).

Jeremy

[polarisrmk]

Originally Posted by oldiesel

The usual culprit is the cruise control amplifier,i am not familiar with the 1995 but on both my cars an 87 and a 91 that part is located just about ahead of your left knee. You have to drop the lower dash to see it,not that seeing it is any use! There is an online troubleshooting guide at http://gdl-online.com that may help you. I recently gave up on the original system in my 87 and installed a Rostra aftermarket unit that is working very well for about $180 which is less than the cost of the reconditioned amplifier from GDL i think. Don

Glancing at a few Mercedes tsb's they all seem to point too the cc amp being under the hood on the passenger side near the windshield. I have not verified this but I always thought it was by your left knee under the dash as well. did they change the location when they went to the 606 NA motor?

[babymog]

The 124 Cruise Control changed in '93 for the M104 (gas) to a completely different system compatible with the electronic throttle of the ASR. It is likely that the '95 E300 also changed to the new system. In the '93-'95 E320 it is a cast-aluminum ECU under the passenger's floormat, not sure what they did with the E300.

Good luck, IIRC the ECU is in the $1200 range. Fortunately, I believe that the newer system was less problematic, provided there wasn't a short in the wiring or other outside influence.

[Jeremy5848]

The OM606 engine in the 1995 W124 chassis uses a mechanical cable throttle similar to the OM602/3 engines in earlier models. Mercedes didn't go to fly-by-wire on the OM606 until the 1996 E300D. The 1995 E300D may still have the older cruise amplifier.

OTOH, the FSM (CD-ROM version) shows N4/1 "Electronic accelerator/cruise control module" as being in the compartment behind the battery. I'm concerned that this may apply to gassers only but there's no note either way in the manual. The list of schematics lists cruise control only for engine 104 and 119, both of which are gassers. The schematic for the OM606 engine lists only engine parts and doesn't include the cruise control. This engine also does not have an electronic accelerator.

The "Model Year 1995 (USA) Model 124.131 Introduction into service" manual doesn't mention cruise control at all, it's pretty much confined to describing the new OM606 engine.

Maybe the OP could pop off the driver's under-dash panel and look? I've run out of places to look!

Jeremy

[babymog]

The non-ASR M104 didn't have an electronic throttle either, but the new cruise was compatible with both, and on the passenger floor. I suspect it's time to look up the part in any of the many on-line parts sources and compare.

[Jeremy5848]

Originally Posted by babymog

The non-ASR M104 didn't have an electronic throttle either, but the new cruise was compatible with both, and on the passenger floor. I suspect it's time to look up the part in any of the many on-line parts sources and compare.

For the 124.131 (1995 E300D) EPC shows a rather poor diagram (as usual) but the electronic "Tempomat" control unit looks like it's under the dash. The part number is 016 545 77 32 "replaced by" 023 545 21 32. It's #5 in the diagram.

There's also a #9 that might be located under the floor but EPC says it's "not applicable" to the 124.133. Perhaps that's the part the gassers use.

Jeremy

[babymog]

#5 in that diagram is the old-style, not what I've seen in the '93-'95 E320. If that's the correct diagram, hopefully it's the older (easier to find and rebuild) amp.

[polarisrmk]

According to WIS the diesel models had an unchanged cruise control design in the 124 from 86 on ... meaning it is the old style under the dash above left knee. I should be able to check tomorrow.

[babymog]

WIS? Pardon my ignorance, but what is WIS?

[Jeremy5848]

WIS is the latest Mercedes electronic shop manual:

"The Workshop Information System (WIS) is a modern DP supported information system.
It not only replaces the workshop documentation available to date on paper and microfilm, but also offers a multitude of possibilities for attaining information required."

See http://www.autoepc4you.com/catalog/view/?id=478 and many other sites or Google "Mercedes WIS."

[polarisrmk]

Originally Posted by Jeremy5848

WIS is the latest Mercedes electronic shop manual:

"The Workshop Information System (WIS) is a modern DP supported information system.
It not only replaces the workshop documentation available to date on paper and microfilm, but also offers a multitude of possibilities for attaining information required."

See http://www.autoepc4you.com/catalog/view/?id=478 and many other sites or Google "Mercedes WIS."

correct ... available to those with a mercedes technician number

[Jeremy5848]

Originally Posted by polarisrmk

correct ... available to those with a mercedes technician number

Ahhh . . . that's why I see so many bootleg copies on the Internet.

[95e300dwez]

The amp is located under the drive sidle dash and I have issues with mine and replaced with two diff. amps and still no cruise.