Cruise control diagnosis and repair

[Randy McCall <randym@schiller.com>]

I'm a new list member, but have kept up with archives for a while now.  I've had a non-functioning CC on my '90 200TQ since its purchase last year and have started into the diagnostics (Bentley) to fix what ails it.  

The Bentley suggests that the diagnosis be done using the connector from the Cruise control brain under the dashboard and above the glove box for all tests, and I am reluctant to dig into that without some additional info.  Bentley is once again not real clear as to the steps for this removal process.  Anyone care to shed some light on removing the dash to access the controller?  Do I need to start with the center console, or can that stay in place?  What kind of nightmares result from trying to reinstall the dash and assorted A/C sensors, HVAC ducting, and other items?  

Then again, can I access all of the current tracks without taking the dash out?  Thanks to a post earlier by Huw I was able to remove and repair the vacum vent switches on the clutch and brake pedals (the brake switch had > 150 ohm resistance, and the clutch was always an open circuit - now total resistance is less than 1 ohm when switches are closed).  I was also able to verify that the vacum pump works when energized outside of the CC circuitry (the Bentley procedure to test using a ground connection to the number 4 terminal resulted in no pump working - Bentley suggests replacing pump at this point).  

My suspicions now are that it is a bad combo switch, and I can continue to test for this after removing the air bag system and steering wheel to access the switch connectors. However, I am wondering if there is a better way to do things.  TIA for any advice.

Thanks,

-Randy McCall

'90 200TQ 	82k mi