Differential lock questions

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <4D230EF0.1299@mailgw.sanders.lmco.com> kirby.a.smith@lmco.com writes:

> Certain models of Audi, such as my 1988 90q, release the differential 
> lock when the speed exceeds about 15 mph.  The signal for this comes 
> from the speedometer and goes to a control module under the rear seat. 

On the MB ur-quattro, it comes from the speedo and fans out to the idle 
stabiliser controller and the differential lock controller.
 
The idle stabiliser controller needs to know road speed so that it can maintain 
a high idle (for brake and steering assist) if the vehicle is still moving but 
out of gear and with the throttle closed.

-- 
 Phil Payne
 Committee Member, UK Audi [ur-]quattro Owners Club