Diagnosing cruise system
 

I am tired of using my foot on long drives and, of course, cruise doesn't work (well duh the amp is here on my desk) I removed it a year ago with the intent on replace it. but... I didn't

I know General Dynamics can refurb the amp as well as the actuator.

How do I test either to make sure they are good? I hope its just the amp because .. jeeze the actuators are expensive.

Performance Products at one time would allow you to buy and install the computer part of the cruise..and if that was not the problem let you return it... to simplify the diagnosis part of the problem.... they also have a great paper catalog with expanded line drawings and proper names for stuff... which can help in posting questions.... or talking to your parts house...

"used to" darn


well is there a way I can test the actuator now to see if its good?

Try here gdl-online.com/test

link no work

I'd really like to diagnose mine too - I take just enough freeway drives that I get tired of manually controlling things. TheDon, my cruise doesn't work either - though all the parts are still in the car.

I'm going to search around to try and get a sense of where best to start, but I'll keep an eye on this thread too to see what all I can learn. I've got a soldering gun and I am not afraid to use it!

I pulled apart my cruise control actuator to see what was wrong with it (also, 3 other failed ones I came across) and 3/4 the failure was two very small but supposed to be very strong tensioning springs inside the assembly, had stretched out, and were no longer keeping the gears together. The motors would actuate just fine in response to signals but couldn't actually move the throttle linkage because there was no connection there. There is also a helical spring which is supposed to hold some sort of metal plate that is connected to the throttle linkage, to a plastic gear, and it lost its tension also and would no longer hold up to the forces of the throttle linkage.

I was unable to correctly find a working spring, and my attempts to shim tension into the one gear with a rubber shim, and file down the plastic gear on the other to allow the metal to cup the plastic fully, were ultimately unsuccessful.

The other failure I found was that the gasket around the motor part of the actuator had failed and the inside had corroded out. Of course, it was also de-tensioned inside, but it was electrically dead as well.

I'm willing to bet that the tensioning system failures are the overwhelming majority of cruise control related failures.

I am not saying ( perhaps you have checked and are saying ?) that Performance Products does not still do that.... I don't know... I just know from reading the paper catalog a couple of years ago that they did at one time and I thought it was a stroke of marketing genius... since I would have no confidence that I could do the electrical checking that unit might require.. ( I did look in the MB FSM.. EEEEKKK )....

I have an aftermarket system from Audiovox that I am going to try and install soon....if it works I'll be one happy guy. :D

It is the system with a brain + vacuum powered acutator.

Test the Actuator
 

Go to www.gdl-online.com Then click the Atom. Then you can enter the site and the test instructions are easy to find. It's a pretty easy test for the actuator but I don't think you can really "test" the amp.

There are some good threads here on resoldering the amp too. Just got to poke around...

When I first bought my 82 300SD the cruise would work occasionally, now it will only accelerate, but not hold the speed. What is usually the cause for this? It would be nice to have the cruise working, but I will not pay the prices for the new parts:eek:

Thanks for that link, I had printed out the procedure a few years ago, and what I typed in was printed on the bottom of the page.

Thats a typical failure symptom of a Bad Cruise Amp....mine did that too when I got it, now it doesn't work at all....which is why I am now going to attempt an aftermarket cruise install....

My only experience with an aftermarket cruise was this, I was sitting at a redlight, talking on my cell phone, and playing with the switch of a non-functioning aftermarket cruise. The clutch line decided to rupture on my 91 F450, and when the truck started to move, the cruise went to full throttle.:eek: Boy am I glad no one was coming through the intersection at the time. I pulled into a parking lot and snatched all of the cruise components off and dropped them into the trashcan right there. I am not sure that I could ever trust an aftermarket cruise after that.:rolleyes:
Jeff

X2, their test procedure is pretty straight forward. Also, make sure all the connections a tight. A few months ago I installed a rebuilt amp from GDL and installed a new actuator, it works perfectly.