Description Adn Operation (page 3 of 4)

SPEED CONTROL 

The speed control system is integrated with the engine management system and uses fuelling intervention to 
automatically maintain a set vehicle speed. Once engaged, the system can also be used to accelerate the vehicle without 
using the accelerator pedal. The speed control system comprises the following components: 
 

On/Off/Suspend switch  
'+' and '–' (set/accelerate and decelerate)  
Resume switch  
Clock spring  
Speed control warning lamp (in the instrument pack)  

The speed control system also uses inputs from the brake pedal switch, the APP sensor, the ECM and the ABS ECU.  
 
The speed control is operated by the driver using only the steering wheel switches. When speed is active, the ECM 
regulates the engine torque to maintain the set speed. 
 

CONTROL SWITCHES 

 
The speed control switches are located on the LH side of the steering wheel. The switches are connected via fly leads 
directly to the clock spring. All of the speed control switches are non-latching momentary rocker switches. The minimum 
set speed for speed control is 18 mph (30 (km/h). Speed control is automatically suspended if the vehicle speed falls 
below 15 mph (24 km/h). 
 
The speed control switches are resistive ladder type switches. There are three switches associated with speed control, 
two of which are for active speed control (where specified). The switches vary the resistance of a signal voltage sent to 
the ECM. The switches receive a 5 volt reference supply which is varied in response to which switches are pressed. 
 
Suspend/Resume Switch  
 
The suspend/resume switch controls the selection of speed control. When the ignition is in position II, a press of the 
suspend switch will activate the suspend mode which temporarily switches off the speed control system, but retains the 
previously set speed in the ECM memory. 
 
Resume Switch  
 
The resume switch re-activates the previously set speed after the speed control has been suspended by pressing the 
suspend switch or by depressing the brake pedal.  

11

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EAT control module

Item  Part Number 

Description 

1

 -

Suspend/Resume switch 

2

 -

Accelerate/Decelerate (+/–) Switches

3

 -

Active cruise control time gap switches

4

 -

Clock spring

5

 -

Wiper control column switch