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2004 DTS - 1989 Coupe de Ville (since sold)
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Discussion Starter #1
Should have called it 'Declining" operation.
My '89's Cruise Control operation has rapidly lost it's effectiveness. It didn't happen instantly, but only took about a week before it stopped working altogether.
The symptoms started with not holding speed on an incline. Next it would not hold consistent speed all the time. Finally stopped working almost completely.

The light comes on with the switch. The speed will hold semi-steady for a few seconds on level ground, but then steadily slow down.

Sounds more like a servo issue than an electrical one, but thought I'd ask to see if others have had this issue. Is there a particular component that this sounds like? If the servo itself, is this a bear to replace? Even though it's right on top, it doesn't look like it's easy to dig into.
Vacuum hoses and cables all appear to be attached and in one piece.

Thanks.

Paul

PS: Did a search to about June of last year and didn't come up with any-
thing that sounded similar.
 

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White Diamond '03 DHS (with DTS floor shift)
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Check the vacuum lines for leaky fittings or cracks. Also check the servo diaphragm to be sure it will hold a vacuum.
 

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95 Fleetwood Brougham / 01 DTS / 11 CTS Lux / 11 DTS Platinum
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Ranger is correct. The 4.5 is also notorious for intake gasket leaks. It's definitely a vacuum problem.
 

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2004 DTS - 1989 Coupe de Ville (since sold)
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52 Posts
Discussion Starter #4
Thanks both of you. I'll dig into it a little more this weekend and see what I find. I do have a vacuum pump/tester and was going to try it anyway, but got discouraged when I couldn't easily get to where the vacuum lines terminated on the servo. And I couldn't even see clearly where the darn mounting attachments were for the thing!
Didn't think about the intake gasket, but it's running pretty good. Smooth idle and still gets in the high-twenties as far as fuel mileage goes. I'll test a few areas anyway though codewize. Just in case...

I guess I should just be happy it's on the top of the engine rather than underneath like the four engine mount/isolaters and the starter I had to change recently.

Thanks again. I'll let you know what I find.

Paul
 

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95 Fleetwood Brougham / 01 DTS / 11 CTS Lux / 11 DTS Platinum
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I think, if I remember correctly, there are three small bolts on the back of it that hold it into a bracket. The vacuum lines are on the bottom, or side. Be careful with those lines, the nipples they attach to are brittle and will break very easily.

I couldn't easily get to where the vacuum lines terminated on the servo. And I couldn't even see clearly where the darn mounting attachments were for the thing!
Paul
 

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2004 DTS - 1989 Coupe de Ville (since sold)
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Discussion Starter #6
Not to dredge up too old of a subject (although I know some of us live that that kind of stuff here!) but I did finally fix the issue.
I must've been looking at it in the dark the first time, because when I went back I could easily see not only the vacuum lines, but also the mounting screws that you mentioned.
After trying to diagnose everything BUT the servo (as in least expensive first) I finally just had to bite the bullet and try a new one.
Bingo! Ok, so I hoped it wouldn't be so I could save a few bucks, but a re-conditioned servo bought from the local auto-parts store did the trick.
Works great now. Happy me.
Thanks for the advice.

Paul
 

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95 Fleetwood Brougham / 01 DTS / 11 CTS Lux / 11 DTS Platinum
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Awesome. That's good to hear. I actually bought a servo on eBay for mine that did NOT fix the problem so maybe I got a second bad servo.

That's good to know.
 

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2004 DTS - 1989 Coupe de Ville (since sold)
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Discussion Starter #8
Was yours a new servo? At least theoretically anyway?
The one I bought came with a big note attached to it spelling out the test procedure for checking your car's system at the connector.
They say to do this BEFORE you plug in the new unit, or damage to the new servo may result. Thereby voiding any warranties.
I can't remember the exact procedure (should have made a copy of the notice) but mine did not seem to give consistent readings anyway, so I just took a chance and hooked it up.

Maybe stop by an auto-parts store and order up a new one, just to check out the instruction sheet.

Paul
 

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95 Fleetwood Brougham / 01 DTS / 11 CTS Lux / 11 DTS Platinum
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Mine was not supposed t be new, but in good working used condition. Interesting.
 
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