how to toubleshoot cruise control

driving over the weekend noticed  my cruise control doesn't work I had the car over a year now its the 1st time I wanted to use it. but anyway no lights come on when I try to use it( cruise control light). I checked the fuse on the driverside everytrhing is fine. any suggestions?thanks for reading!

Rivieraz wrote:

driving over the weekend noticed  my cruise control doesn't work I had the car over a year now its the 1st time I wanted to use it. but anyway no lights come on when I try to use it( cruise control light). I checked the fuse on the driverside everytrhing is fine. any suggestions?thanks for reading!

...did you get a service manual set yet?  There is trouble shooting in there.  That said, generally need to check the brake switch, cruise servo, the column switch. My wild guess is you'll need to replace the control unit with one from a junkyard (there are a lot of them around).

albertj wrote:

Rivieraz wrote:

driving over the weekend noticed  my cruise control doesn't work I had the car over a year now its the 1st time I wanted to use it. but anyway no lights come on when I try to use it( cruise control light). I checked the fuse on the driverside everytrhing is fine. any suggestions?thanks for reading!

...did you get a service manual set yet?  There is trouble shooting in there.  That said, generally need to check the brake switch, cruise servo, the column switch. My wild guess is you'll need to replace the control unit with one from a junkyard (there are a lot of them around).

My cruise stopped working. I have an extra control unit. Albert, have you done this? How does it come off the firewall. You have to get to the back side to unbolt it?

LARRY70GS wrote:

albertj wrote:

Rivieraz wrote:

driving over the weekend noticed  my cruise control doesn't work I had the car over a year now its the 1st time I wanted to use it. but anyway no lights come on when I try to use it( cruise control light). I checked the fuse on the driverside everytrhing is fine. any suggestions?thanks for reading!

...did you get a service manual set yet?  There is trouble shooting in there.  That said, generally need to check the brake switch, cruise servo, the column switch. My wild guess is you'll need to replace the control unit with one from a junkyard (there are a lot of them around).

My cruise stopped working.  I have an extra control unit.  Albert, have you done this?  How does it come off the firewall.  You have to get to the back side to unbolt it?

I have not done this and I don't expect my CC servo to ever break, it's electronic.  That said, GM does not have much variation at all in hard parts like that (brake light switches, cruise control modules, etc.) so my guess is you should find a few torx, hex head, or Phillips head body panel sheet metal screws around the outside of the unit holding it on, probably thru ears on the metal base or some such. The place for super careful work actually would be the plastic throttle connectors.  They are tricky.  Study the ones on the cables to the replacement control unit *very* carefully.  You will probably need a "pick" to get them off and even them they are old and likely will be brittle so be careful.

thanks everyone,i do have the sevice manuals,for me im  learning as I go sometime the manuals are a little hard to read for me but anyway, I have some time this week to tackle the C.C.   going through the manuals 2night. also I have a set of blue 1995 FSM manuals for the price of postage if needed.

Rivieraz wrote:

thanks everyone,i do have the sevice manuals,for me im  learning as I go sometime the manuals are a little hard to read for me but anyway, I have some time this week to tackle the C.C.   going through the manuals 2night. also I have a set of blue manuals for the price of postage if needed.

For the Riv, the factory manuals are pretty much an ownership requirement at this point. One of the problems with the manuals is that they either assume you have an experienced handyman's or trained mechanic's know - how, and they sometimes skip stuff. For instance, for replacing the front control arms they factory manual does not tell you that you have to smack the ball joint while using the factory tool in order to get the assembly out. The only point of using the tool, however, is that the way the ball joint is in, if you use a pickle fork you will damage the ball joint and boot because of lack of clearance for working. Another is the serpentine belt replacement on the 2000 Cavalier/Sunfire, for instance. The manual shows a multi-step procedure involving a special tool -- however, the real tool is a broomstick (yes, a broomstick). If you have a broomstick and you know just where to lever it (once someone shows you you can't possibly un-see it) it actually takes longer to read the factory manual instructions than it does to change the belt.

Point is the manuals are definitely useful but the normal cautions you already know are definitely applicable: (1) don't check your brains at the door, so to speak - make sure what you see in the manual comports with common mechanical sense and (2) don't be shy about asking someone who's actually done the more complicated jobs, as long as they truly have a clue (some mechanics do, some don't).

thanks albertj

messed with c.c. but didn't get to work yet,i had a friend use his power probe to test 1st with ignition off then on he said that it was getting power(not sure what voltage or ohms he read but said it was fine) and when I removed the vacuum line behind the servo It gave a good strong hisss,no noticeable dry rot or cracks in hoses.also albertj when you say it might be the control unit do you mean cruise control servo? 2marrow im gonna peek at the column for the brake switch

note: this is repetitive.

the cruise on my 1995 riv failed.
a pull-a-part cruise unit fixed it.
next time i was there i bought another ($35) and installed it in the parking lot.
it worked so now i had the pull-a-part unit which was formerly screwed to the firewall bracket as as a spare.
it lived in the trunk until i sold the car.

the cruise on my 1997 riv failed.
the extra cruise unit from the 1995 riv fixed it.
next time i was trolling the junkyard i bought another cruise module (again, $35) and installed it in the parking lot.
it worked fine so now i had the one which was formerly screwed to the firewall bracket as as a spare
which still lives in the trunk.

the cruise on my [back-up road-driver] 1997 buick century failed.
a pull-a-part cruise unit fixed it. [it is a slightly different part than the riv cruise unit]
next time i was at the junkyard i bought another (cost $35) and installed it on the century in the parking lot.
it worked so now i had the one which was formerly screwed to the firewall bracket as as a known working
spare which still lives in the trunk of the elderly century.

as an aside,
the bracket on which the cruise module is mounted has elongated slots for the bolts
which ease removal. save the extra rubber mounting grommets.

also:
the throttle cable is pulled by a fabric-like ribbon located inside the cruise unit.
it's necc to disconnect the cruise cable at the throttle body so as to get sufficient slack
to disengage the pull-cable.

the rock auto website lists what cars use the same cruise unit as our 8gen rivieras.

Rivieraz wrote:

messed with c.c. but didn't get to work yet,i had a friend use his power probe to test 1st with ignition off then on he said that it was getting power(not sure what voltage or ohms he read but said it was fine) and when I removed the vacuum line behind the servo It gave a good strong hisss,no noticeable dry rot or cracks in hoses.also albertj  when you say it might be the control unit do you mean cruise control servo? 2marrow im gonna peek at the column for the brake switch

My unit is an electronic servo. If yours is a vac servo, since it seems to be working I'd check the brake switches with a meter. One controls the lights and the other is for cruise. Lights are easy... do the light up? The other one, you can check it with a meter.

ordered brake switch from rock auto, it came to 10 dollars and change.

Rivieraz wrote:

ordered brake switch from rock auto, it came to 10 dollars and change.

Was your obviously broken? I remember when mine quit, it was seriously annoying. I had stopped to get gas at the Marathon on Greentree Hill and when I finished, restarted the car, the idiot light on the instrument cluster stayed on and the gong started ringing. It took a while to figure out how to rig it so I could drive and it was a long drive back to NY without cruise.

no i didn't even get to check the brake switch yet,it was 7dollars and some change plus tax and postage, so I bought it just in case. 2marrow or the next day im gonna check it.i have a silly question about the c.c. when I turn the key half way, all the dash lights lights up even the c.c. light, but when im driving the car and engage the c.c. the light does not come on at all. so my silly question is when the c.c isn't working properly but when I try to engage it should I see the c.c light at all?visually the engine vacuum source looks fine also the the vacuum check valve so is there anyway to check them to see if they are working properly. I believe the servo to vacuum source hose is what gave the hisss? I'm kinda new at this so please let me know if I miss label something thank again everone

albertj wrote:

I have not done this and I don't expect my CC servo to ever break, it's electronic.

Hi Albert,
I grabbed this quote from your Aug. 2020 conversation with Larry about cruise control issues and am wondering about the electronic replacement you use for the servo unit.
I should have prefaced this with he fact that I have a non-functioning CC in my '98 Riv.
It's the next thing on the list to fix, and I want to gather the parts I may need, even if I haven't yet diagnosed the problem.
Please tell me about the unit, and where I might find.
I'd like to do this fix once and for always, eh?
TY,
Sean

Yeah,
I also found this quote, later:

albertj wrote:

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

Since I have a '98, my question is moot.

Thanks anyway

denim wrote:

Yeah,
I also found this quote, later:

albertj wrote:

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

Since I have a '98, my question is moot.

Thanks anyway

It is worth the time to diagnose the problem.


The brake switch is actually several switches in one housing. GM has been using a brake light switch of generally this style since Methusela was a toddler. When they went to an electronic CC servo they replaced the vacuum side of the brake light switch with a reed switch, but the general shape and the brake light side of the switch is still the same. It's a clever gadget, and if you put it in per the instructions, it self-adjusts (such adjustment is needed only once).

My guess is your headache is the brake switch or maybe the servo but no kidding do the diagnosis. And if you smell a rat, maybe it's the one that chewed on your wires...

I'm having a friend, with a more advanced scanner, help soon, so I can follow the manual. Particularly the Fault Isolation Test.
There is no power whatsoever now. Zip. Checked fuse. Replaced, no change.
Also, curiously, my steering wheel has a bit of front-to-back movement. Hoping that's not built in so I can hand the wheel to Moe when he asks to take the wheel.
Maybe someone was messing with it.
Further investigation needed.

denim wrote:

Also, curiously, my steering wheel has a bit of front-to-back movement. Hoping that's not built in so I can hand the wheel to Moe when he asks to take the wheel.
Maybe someone was messing with it.
Further investigation needed.

That's a VERY COMMON problem with the Riviera. The Column tilt mechanism, pivots on two bushings/pins. The pins work themselves out over time and the whole column rocks back and forth. There is actually an entire thread dedicated to it. Surprised you never saw it, you have been here awhile.

Here it is,

https://rivperformance.editboard.com/t6471-faq-steering-column-slop-problems-replacement?highlight=steerining+column


Read through the whole thread.  I fixed mine about 90%.  I tapped an exiting hole in the column and used a metal strap and bolt/screw to hold the pin in.

Page10.

https://2img.net/h/i172.photobucket.com/albums/w20/SLD1624/SteeringFix_zpsvcwxymsy.jpg

Thanks much, Larry.
I may have come across this thread myself if the issue was on the short list of problems, most of which have been solved by now.
I looked briefly and saw a lot of grrring about the problem, along with the PITA acronym, so I'm sure it will be a valuable read.
If it comes down to it, do you know if a '95 steering column can replace a '98 column?
My older Riv, which has a great engine/tranny combo, and will be sold for such this summer, could be a donor if so.
This is assuming I can't fix the existing hardware.
Anyway, I'll let you know how it works out.