I've had my beemer since early 2002. The cruise control has never worked. I've replaced the servo and the control unit several times from the boneyard. It's never made a difference. Sometimes I take the parts back for credit, sometimes I forget.

Today I put in those two units from an E-30 that had an odo reading of 130K. Who knows, might be accurate. Still doesn't work.

It's not that big of a deal, but on long trips it is a luxury and might help me avoid a ticket or two.

I've heard new parts wil set you back $1,000. I don't want it that bad.

Any master speedo dudes out there?

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1986 300SDL, 362K
1984 300D, 138K

Do you have a wiring diagram? It seems you have ruled out the servo actuator. I am guessing this is the standard vacuum powered type? There is usually a switch somewhere in the brake system to disengage it. You need to check out all the inputs. It could be a alot of things. You might try www.bimmerforums.com. It's pretty good for Beemers.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

Does it activate but not hold speed? If it activates, the servo is good, the brain is dead. If the servo does not activate, check to see if there is any voltage to it.

Usually CC's have their own speed sensors, they don't use the speedo.

Hell, on MB's of vintage, if you put in the wrong taillight bulb, it would mess up the brain, its hooked into the brake light circuit. Sounds like Urban Legend, but I heard it several times.

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MB-less

In my Bentley guide, they say that the CC is indeed connected to ground through the brake light circuit, or something like that. The only thing I haven't tracked down of the checkable items is the actual CC switch, a lever on the column. And BTW, it doesn't even begin to work. It behaves completely dead.

I took one of the servos apart one time, years ago, cuz I had about 3 of them , non of them worked, so I thought, why not dissect one of the PsOS.

It looked like strictly an electrical device. No vacuum hookup anyway. If I find one of the others, I'll bust it up and post a pic. I found one web site back when who claimed to be able to refurbish the units for a modest price. I could never get them to accept my unit in the mail. I couldn't figure out what their trip was.

Best I can gather through the years (it's not a major priority but I've always had an ear out for it) the computer brain is what is usually bad, if none of the clutch, brake, or CC switches is bad that is.

I dunno, the advice of my metal fabricator guy neighbor at my warehouse is sounding more astute all the time. He just bought a new Dodge with dually, 1 ton I guess, w/ Cummins diesel. He sees me working on my rigs all the time and a few days back he said, "What you need to do is take off the radiator cap, hang it down from the top of your garage , and back a new car under that sum-*****." He's one of them California guys you hear about.

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1986 300SDL, 362K
1984 300D, 138K

I posted on Bimmerfest, I'll go check out the B-forums. I should check the switches again. It's been a while but I checked them in an earlier trial.

The Bentley guide does have a diagram, I should try to read it. It's not that tough but it does take some focus.

I've been told by old Bimmer hands that it's a nice CC when it's working. I've definitely driven some that weren't as good as others.

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1986 300SDL, 362K
1984 300D, 138K

Did you try r3vlimited.com?


My friend frequents that forum, and he swears by it.

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-Justin

91 560 SEC AMG - other dogs dd
01 Honda S2000 - dogs dd
07 MB ML320 CDI - dd
16 Lexus IS250 - wifes dd

it's automatic.

Thanks for the tip. The other two, B-fest and B-forums, are OK but not as good as this one (MS) IMO.

I'll get into it tomorrow when I'm awake.

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1986 300SDL, 362K
1984 300D, 138K