[Sinfonian]

Greetings to all from sunny Florida --

This is my first post (although I have read the site regularly since acquiring my Saab in March), so I apologize if I'm not following protocol in any way.

I have a 2000 9-3 SE turbo convertible, manual transmission, 76K miles (when I got it in March, it only had 58K!). I have used only premium gasoline and changed the oil (Mobil 1 full synthetic) regularly. I love my Saab and want everything to work ... it has its quirks but I'm learning how to repair things myself as much as possible.

The other day on the highway, traveling about 78 MPH with cruise control on, the cruise spontaneously quit. Unlike the other failed cruise control threads I've read here, though, the CRUISE light went out at the time and it DOES NOT come back on at all when I move the switch on the wand. That seems to rule out the brake pedal switch at least...

What might be the cause of cruise control failure where the light is off? Thank you all in advance for your help!

 

['97 Saab SE Turbo]

Just make sure that the brake pedal and clutch pedal are at their upper most positions (using your toe to move the pedals uP) before engaging the cruise control.

If that doesn't help, use a multimeter set on resistance to verify the continuity (normally closed) of the brake and/or clutch pedals... Ron

 

[Ld_rider]

The other day on the highway, traveling about 78 MPH with cruise control on, the cruise spontaneously quit. Unlike the other failed cruise control threads I've read here, though, the CRUISE light went out at the time and it DOES NOT come back on at all when I move the switch on the wand.

My 900s w/auto does the same thing. It will work perfectly for a week or so, and then spontaneously quit. Like yours, mine also drops the cruise light and no matter how many times I tap the stalk to turn it back on it....won't. It always works after being shut off for awhile...

Don't think it has anything to do with the pedals, since when the cruise is disengaged with the brake, the light still stays on (waiting for the resume). Believe it or not, I think my issue is related to a battery that might be a little weak.....

 

[BobSaabit]

I'd be suspicious of the switch itself or the connection. On a T7, the cruise is all handled by the ECU electronically: You push the switch, a signal goes to the ECU, it handles the throttle position to give you the MPH you requested. No cables, no other control units, etc. Just a quick signal on the bus.

The cruise will not refuse to turn on if the brake or clutch is being pressed at the time you push the switch, so it's likely not one of those switches. You can't set a speed, but you can turn it on and get the dash light. (I've only tested that in the driveway - start car, step on brake, engage cruise, should light up ... you can do the same test).

Just to verify... your speed began to drop, correct ? i.e. it wasn't just the bulb burning out?

Do all your other features still work: speedometer, TCS, ABS, etc? Anything at all not working?

You could probably source a used stalk for short money on Ebay or here in the For Sale / Parting Out section. You need one from a 9-3. Easy swap, but disconnect the battery first. Pull the steering wheel out as far as it goes. Take out the screws holding the shroud on the column. Switch just unclips on the top and bottom, diconnect connector, and it's out.

I can't recall if you have to take the lower dash plastic off to get to the screws on the column shroud. Off the top of my head, that's two screws in the front, one to the center console rear edge, two for the ODBII connector, One 10mm bolt on the door jamb, two screws in the fusebox area. You will have to pull the rubber door trim off in the fusebox area for a short distance.

EDIT: You could also test your switch once you get it out, but for the price, I'd just buy one and swap to save labor. Also, I've never heard of one of these going bad, but I can't think of anything else aside from a connection between the switch and the ECU.

 

[BobSaabit]

One more thought... maybe a better one: If you have a Diagnostic Trouble Code (DTC) stored that's related to the throttle position process then the cruise would refuse to engage. The only way to find out would be to engage the services of a Dealer or Indy that has a Tech II device to read out the codes. The throttle bodies on these can have problems, although yours is a little light in the miles for it, it's possible.

From the WIS:
Diagnostics
•
The diagnostic tool contains a menu that indicates the condition that has not been
fulfilled if cruise control cannot be engaged. Another menu indicates the reason why
cruise control was disengaged when it was last used.
• If the input from the brake light switch is continuously B+, diagnostic trouble code
P1576 will be generated. If the input from the brake light switch is continuously 0V,
diagnostic trouble code P1577 will be generated.

System reaction to a fault

• Cruise control will be blocked if a fault occurs on the input from the brake light
switch.

 

[Sinfonian]

Update: figured it out and fixed it

Sorry for not replying sooner -- I thought I had. Anyway, turns out the throttle body was bad. The car began to conk out while driving; although it could be restarted right away (after stopping), it was annoying and potentially dangerous!

I found a used throttle body at a u-pick-em junkyard and, thanks to instructions elsewhere on this forum, I replaced the throttle body myself. It wasn't the structural part but the electronic part that was the problem -- it was reading the wrong fuel/air mixture. No problems (with that) since!