So my cruise never worked in my 1987 300D Turbo. I replaced the amplifier/transducer/computer, whatever is the correct term. Aka, silver box in the dash. Now I can accelerate with the stalk (it did nothing before) but when I let go it looses all its speed. So it accels, but it won't set. Is this this a bad computer or is something not holding vacuum? Where are the vacuum components of the cruise system if there are any?

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68 280SL - 70 280SL - 70 300SEL 3.5 - 72 350SL - 72 280SEL 4.5 - 72 220 - 72 220D - 73 450SL - 84 230GE - 87 200TD - 90 190E 2.0 - 03 G500

Nissan GTR - Nissan Skyline GTS25T - Toyota GTFour - Rover Mini - Toyota Land Cruiser HJ60 - Cadillac Eldorado - BMW E30 - BMW 135i

ok this is a little embarassing for me . . .


my cruise worked the exact same way as your is working now. . until I learned that you need to have your foot on the accelerator AND hit the cruise stalk AT THE SAME TIME. . .

I was used to Ford and VW cruise systems where you hit the button. . and speed is set.

so try accelerating with your foot, and hitting the stalk. when you let go (with foot and hand) she should hold speed

I hope its that simple for you (as it turns it was for me)

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87' 300DT (Grey w/ red leather)
87' 300TDT (silver w/ palamino tex) SOLD

2012 VW JSW TDI (on tdiclub.com all the time "btcost")

If the amplifier (what you replaced) is good then the only other component to cause your failure mode would be the actuator, which is electric, not vacuum. It lives on the left (driver) side of the engine, down under the intake manifold with the throttle linkages.

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"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

If I can accelerate with the rod I would think the amplifier is good and if the actuator pulls the cable, it should be good too. I'm going to go see if it is operator error.

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68 280SL - 70 280SL - 70 300SEL 3.5 - 72 350SL - 72 280SEL 4.5 - 72 220 - 72 220D - 73 450SL - 84 230GE - 87 200TD - 90 190E 2.0 - 03 G500

Nissan GTR - Nissan Skyline GTS25T - Toyota GTFour - Rover Mini - Toyota Land Cruiser HJ60 - Cadillac Eldorado - BMW E30 - BMW 135i

Sounds like it might not be getting a speed signal.

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Gone to the dark side

- Jeff

What would cause that?

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68 280SL - 70 280SL - 70 300SEL 3.5 - 72 350SL - 72 280SEL 4.5 - 72 220 - 72 220D - 73 450SL - 84 230GE - 87 200TD - 90 190E 2.0 - 03 G500

Nissan GTR - Nissan Skyline GTS25T - Toyota GTFour - Rover Mini - Toyota Land Cruiser HJ60 - Cadillac Eldorado - BMW E30 - BMW 135i

? Don't know.

I had one that would do everything but resume, replaced the stalk/switch and it was fine. I haven't had your symptom however, hold the accel and let go, it holds speed, hold the decel and release, it holds speed.

__________________

Gone to the dark side

- Jeff

Oh, sorry. You're previous post made it sound like you knew the problem haha. Sorry Jeff I assume you have ALL the answers.

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68 280SL - 70 280SL - 70 300SEL 3.5 - 72 350SL - 72 280SEL 4.5 - 72 220 - 72 220D - 73 450SL - 84 230GE - 87 200TD - 90 190E 2.0 - 03 G500

Nissan GTR - Nissan Skyline GTS25T - Toyota GTFour - Rover Mini - Toyota Land Cruiser HJ60 - Cadillac Eldorado - BMW E30 - BMW 135i

Nah, just all the parts to swap and find the answer. Easier to be well equipped than smart sometimes.

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Gone to the dark side

- Jeff

Parts cars are a dangerous thing. I had two fiero parts cars one time and instead of fixing a friends car I just replaced half his car haha.

Yeah, the Fiasco. I remember driving a new '88 GT on its way to the crusher.

I happened to think of the obvious: If your tires aren't the same size/construction/inflation the cruise control will see different rotation speeds as tire slippage, and will not set.

__________________

Gone to the dark side

- Jeff

Fieros are cool!

So now my cruise doesn't work at all. Doesn't even do the accel only. My tires are new and all the same size.

iPhone post from the bar, I am contemplating.

hmmm. iphone post from the bar... don't get too upset about the cruise and drink so you can't drive...

I drive so I can't drink.

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Gone to the dark side

- Jeff

Lol, World Cup was on and its trivia night. I wasn't going to get hammered to forget about my W124 Woes.

Is it possible my amplifier only had 3 clicks left in it, or should I replace something else?