Been getting some guidance from jamesdean on this...thought I'd see if others want to chime in....apparently intermittent cruise issues can be tough to troubleshoot.

91 300D....26k miles and five years ago I had GDL rebuild my cruise amp and do an actuator tune-up. Has worked perfectly ever since.

Until recently. Now the cruise either works or it doesn't. On a given trip it will either work perfectly or not at all. For example, this morning on an 11 mile trip it wouldn't work at all....but coming home three hours later it worked perfectly. When it works, there is never any drop out or surging.

The only think I've done so far is reseat the plug in the engine compartment (where the cord from the actuator connects).

Do these symptoms suggest anything as to where the problem may lie?

Interestingly, I have another rebuilt amp...this one rebuilt by jamesdean...that's been just sitting on a shelf. So at some point I could try swapping. But if the actuator is the problem, I wouldn't want to run the risk of damaging (by excessive current draw) the amp....been there, done that. But, as I understand it, the only danger is blowing the output transistors...and clearly that hasn't happened.

Thanks.

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14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

What is the part number of the cruise electronic unit? If it is 014-545-40-32, where the important number is the '014,' replace it with an '016' or newer. I had occasional no-work problems with the cruise in my '95 E300 until I replaced it with a newer unit.

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Amp is 005 545 05 32.

__________________
14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Looks like most up-to-date one for mine is 023 545 21 32 (according to EPC).

__________________
14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

The 023 is about as up-to-date as you can get for a124. Failures in the latest versions are much less likely.

If you have not already checked the entire brake light electrical circuit, I suggest you do. Any failure of that sub-system will have the cruise brain thinking the brakes are on.

Jeremy

Your symptoms of temperature related failure are consistent with the failure mode of the cruise control on my ex-1990 560SEL.

JamesDean rebuilt the underdash unit, and that fixed the problem.

Not certain about the 95 diesel, since it retained some early features (the gas cars were updated), but the M104 cars have a completely different cruise system than the earlier cars ( M103 and OM60X).

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

The '95 E300D still uses the older cruise control electronics.

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970