FAQ: Cruise Control Problems

John,

I have the same problem and am trying to diagnose. This arose after a transmission rebuild. I am taking Andrew's advice now and checking these areas. Mine is the Series 1 Supercharged. I replaced the brake switches. Still nothing. Did you have any luck resolving your issue? Stumped and need help.

Drew

Drew,
I have not resolved the issue yet. I was thinking the switch and then when I have time checking the vacuum lines. If you come up with any revelations, please let me know. Thanks.

I have the problem with my '95 occasionally, when mine doesn't work I unplug the connector at the modulator, clean the connections, plug it back in, and that takes care of my problem. Not sure if the connections are corroding from me cleaning it under the hood or not but that makes it work for me

My 95's cruise is in n out all the time. Where is the servo located so I can give the in/re plugging a try

TTT - same question haha. Can anyone help me locate the cruise control module so I can try unplugging, cleaning, and reconnecting it? Pretty please?

llamalor2112 wrote:

TTT - same question haha. Can anyone help me locate the cruise control module so I can try unplugging, cleaning, and reconnecting it? Pretty please?

On my 98, it is on the firewall, center, to the left of the W/W motor.

LARRY70GS wrote:

llamalor2112 wrote:

TTT - same question haha. Can anyone help me locate the cruise control module so I can try unplugging, cleaning, and reconnecting it? Pretty please?

On my 98, it is on the firewall, center, to the left of the W/W motor.

The 96 and later had electronic servo cruise, the 95 had a vacuum servo.

I can't help with this one but would someone with a manual please chime in - - and by the way manuals are not too tough to find on eBay, if you're going to keep the car any length of time I urge you to get a set.

Finally, you may be able to get the needed info at your regional public library, just ask at the reference desk -- you'd be surprised.

Looking down from the driver's side, you can see it below the air intake, the master cylinder, and the overflow tank ... see below.



And, looking from the front you can see the connector, there is the usual tab to release it, see the arrow ...



This is what it looks like on my '95. I could scan diagrams from the service manual but this is quicker for me, that might take a few more days.

HTH

Beautiful!! Thanks so very much, that is as clear as anyone could possibly be
I'm waiting on my new radiator to get here and figured this'd be a good issue to knock out in the meantime. I'll give it a good cleaning n replugging and test it out once the new rad is in.
And Albert, riv encylcopedia on legs , I've got the manuals on my Christmas list this year haha

Sorry for reviving an old topic, but just thought I'd throw in a cruise control problem solution: replace the module. The cruise in my old man's '95 hit the dumps recently... the Cruise light would come on for a split second when engaged, but would instantly turn off and there would be no functionality at all.

We tested the former stock unit for any vacuum leaks, cleaned the electrical connector and prongs, etc. but to no avail. So, I just picked up a used module from a wrecked '95, installed it today and everything works like a top. Inspecting the old unit, there were no cracks that may interfere with vacuum or anything, so prob just a bad unit.

Btw Randall, thx for those pics of the 95 unit's location... I know right where my 98's is but the 95 is totally different.

Hi guys, my riviera has wheel bearing problems that I'm fixing today, it also has an egr tube leak I'm fixing also. I cleaning my engine bay with degreaser and water. But before all this cruise control would work sometimes and not work. I could start the car up, use my cruise control on my way to work. Stop at a light and boom, doesnt work. Now my cruise control hasn't been working at all. I flip the switch, hit the button, the light comes on. But doesn't work. Any ideas?

There is a write-up on the forum about it, somewhere?

I have had good luck with just unplugging the connector, cleaning the contacts, and plugging it back in. This has worked on my '95 a few times and seems to last a good long time?

Awesome thanks I'll try that, where could I find this connected?

Same solution works on mine. Not home but here's a pic on my phone of the reatta. Same deal. Cruise servo is the round metal unit with the elec plug on front. Below n to the side of your throttle body

Here's where it is on my '95, I found my previous post ...

99Rivman wrote:

Looking down from the driver's side, you can see it below the air intake, the master cylinder, and the overflow tank ... see below.



And, looking from the front you can see the connector, there is the usual tab to release it, see the arrow ...



This is what it looks like on my '95. I could scan diagrams from the service manual but this is quicker for me, that might take a few more days.

HTH

This is awesome but I have to say my 96 sc, is a little different, I can't find it, thanks for the pics tho! I'll have to do some more research

But as soon as I find the clip I'm going to clean it and plug it back in I bet it will work after that!

I've been trying to get this car fixed up. I finally fixed my P1640 problem (for now) but a problem I've had since getting the vehicle was that the cruise would randomly disengage while driving. There would be about 15-30 seconds where the car would not want to accelerate, like it had very little power. There would also be a distinct smell, not sure how to explain it. After about 30 seconds, it usually gets better and I can eventually use my cruise control again. I had plans to get a new ignition module + coils...there's a seller who sells the entire kit for $100, and they are all supposedly ACDelco parts. At some point, someone changed either 1 or 2 of the coils on my car. One of the coils has gold posts on top, the other two have silver, and one of them looks different than the others. Anyway, does anyone have any thoughts?

I have installed: new ACDelco plugs (41-601), ACDelco 8MM wires, new BCS, purge valve solenoid, PCV valve, replaced some vacuum lines, etc.

ALSO! My car runs at about 1550 RPM cruising at 60 MPH. Does this sound right? It seems a little low...

Hi Will,

Please go to your Profile and add (and enable) a signature with the year of your car and some basic info like NA or SC. That said - what year are we talking about here? Supercharged or not?

RPMs at 60? Sounds okay.

It seems like you have a bad ground somewhere to me.

Whoops. 95 Rivy, supercharged.

Is there a list somewhere of all ground points?

I'm really not that concerned with the cruise control aspect of this, am just curious if it's related.

I'm mostly concerned with the fact that my car will refuse to go faster/accelerate, usually in the 45-50 MPH range, sometimes. Then the car lets off a funny smell...it's not coolant or oil or anything. I changed my o2 sensor and fuel filter today, still does it.

It seems like this happens most of the time, if I go above 60 and then slow down/brake. It gets stuck in some kind of powerless mode unless I slow down around 40. Then it accelerates just fine, even back up to 60. I just put a bottle of Lucas in the transmission but I'm guessing I will be due for a fluid and filter change, soon. The fluid on the dipstick does not look or smell burnt but only has a slightly pinkish color to it. Does anyone know about this problem and if a fluid&filter change will cure it? I'm really hoping it isn't anything worse...

I'm guessing you have a stuck TCC solenoid - that controls the torque converter lockup clutch. When you come to a complete stop, does the car pull kinda strong at idle? Does it shift firmer than you would expect?

I don't recall it pulling much at idle. The shifts are always smooth, no stuttering or hesitation. They don't seem "hard" or anything. They seem fairly healthy to me.

Is there any way to clean the TCC solenoid without physically accessing it? My understanding is that it is a pain to get to on these cars, especially the 96+. I'm guessing it comes in contact with transmission fluid...would running a cleaner through (such as Trans X) and/or the fluid and filter change possibly help clean it out?

Not really. That was just a wild guess about why you might have stumbling or 'slow' areas. Your answer rules out that guess.

***UPDATE***

Okay so I was playing around with my car and noticed something about the problem I am having.

If I am cruising down the road at 60 miles per hour, with or without cruise control. If I brake AT ALL to slow down...I enter this state of having no power, until I slow down to about 42-45.

If I am cruising down the road at 60 miles per hour, with or without cruise control and I slow down naturally by COASTING...the problem does not appear at all. If I slow down to 50, I can accelerate just fine. What the hell does this mean?