DSTC won't disengage

[Dirtbag454]

I have a 2000 S-80. Last smog check (California) I had to find a shop that would "except" the car and test it off the dyno as the DSTC would not disengage. Car was totally confused by the spinning front wheels and the stationary rear wheels. Smog tech wasn't too happy either. The ABS system seems to be working correctly. I simply cannot get the switch to operate and disengage the system. I'm baffled how to remove that lower switch panel below the climate controls. It has been my experience that these sorts of things are very simple, once you know the "secret". Does anybody know the secret handshake that releases the lower switch panel? I'm a fairly competent mechanic, but this is like trying to find the missing numbers on a "hard" sudoko puzzle.
I have a hunch that the switch is dirty. My daughter had been driving the car for a while, and had spilled soft drinks on the center console many times...enough so that the shifter quit working. I suspect that I will find drink debris in the switch. A good cleaning may restore function. I just have to get TO the switch. Any and all help/advice will be greatly appreciated

[jimmy57]

the trim piece that surrounds those switches pries out easily. The trim is roughly 1 inch tall and the width of the panel. The switch pulls out easily and those switches can be put wherever you want them. Their position is irrelevant. The switch produces a pulse when depressed and the pulse is unique to each type of switch. The switches are plugged into a buss. Since the buss is common to all switch locations the signal from switch determines what happens when it is depressed, not its position.

[Dirtbag454]

Thanks Jimmy57. I'll attack the center console later today and update my progress.

[Dirtbag454]

well, not exactly "later today", but the switch is exposed. I was hoping to find all kinds of muck on and around it, but not so. Once again, the Volvo "secret handshake" has revealed itself. While looking for a likely spot to start prying, I noticed a tiny hole at the seam of the switch panel and plastic fascia. It is on the top edge, between the right-most switch (or blank) and the cigarette lighter. A 90° 1/16" bend in the end of straightened paper clip makes a great tool for pulling the panel. no visible damage!
It is now time to CAREFULLY pry the switch apart. Maybe I'll find a bit of crud.

[Dirtbag454]

Just checking in on this topic. Dismantled the switch. Sadly, it was clean, no crud. I scrubbed the contact surface with a pencil eraser just for grins and reassembled the console. I turned on the ignition switch and pressed the button to see if the DSTC would disengage, but it did not. I'm wondering if the engine has to be running for this feature to be enabled. I cannot start it because I have dismantled a bunch of stuff to replace the two heater hoses and the O-rings on the core. The timing belt is next, when the heater hose portion of this project is done. Then, the ball joints...and then the crankcase vent system. Each repair in turn...don't want too many unfinished projects co-mingling parts on the bench.

[jimmy57]

The CCM would need to be scanned to see if it is registering the input from switch. The fault may be in the CCM.

[yuckuJackD]

Just to ensure the proper operating with the DSTC switch:

Engine ON
Press and hold for 1-2 seconds the button.
On the dashboard (DIM) the light stays ON, that means DSTC is OFF.

to totally desingage DSTS switch it on and off 5 times.
Good Luck

[Dirtbag454]

Thanks yuckuJackD and Jimmy57. I'll try the switch operation as soon as I restore the car to running condition (finish the heater hose project and refill the coolant). If the button operates, Hooray! If not, off to have the CCM (computer control module?) scanned. Spent a lot of time and money having the problem diagnosed about a year ago, and am no closer to solution, or maybe I am. We'll see.

[yuckuJackD]

CCM = Climate Control Module
DIM = Drivers Information Module
CEM - Central Electronic Modulet (the main brain in the car)
and so on ...

p.s. Here are listed, I belive, all modules compaired by high and low speed comunications

HIGH SPEED

Electronic Throttle Module (ETM) -- Controls engine power

Transmission Control Module (TCM) -- Senses driver's style -- how fast the accelerator is depressed, for example -- and adjusts the gear-change sensitivity of the electronically controlled automatic transmission.

Engine Control Module (ECM) -- Controls engine functions like electronic fuel injection, increasing or reducing torque as commanded by other computers in car

Antilock Braking System (ABS) -- Works with Dynamic Stability and Traction Control (DSTC) to prevent skids

Steering Wheel Module (SWM) -- Controls electrical functions on the steering wheel, including radio and climate control

Central Electronic Module (CEM) -- The network toaster computer, it coordinates the diagnostics functions

LOW SPEED

Upper Electronic Module (UEM) -- Controls electrical functions like map lights and rear-view mirror

Supplemental Restraint System (SRS) -- Controls the car's safety system, including driver and passenger air bags, two side-impact air bags, two inflatable curtains, and seat belt tensioners

Climate Control Module (CCM)

Audio Module

Driver's Door Module (DDM) -- Controls the power windows and door locks on the driver's door

Driver Information Module (DIM) -- Controls the instrument panel

Phone Module

Passenger Door Module (PDM) -- Controls passenger-door locks and windows

Rear Electronic Module (REM) -- Controls electrical functions like rear window defroster

Power Seat Module (PSM) -- Controls the driver's seat functions including heating and automatic adjustments.

Good luck

[Dirtbag454]

yuckuJackD, Thanks for the module designation information. I'll print and save that.