Suspension Control Module: Description and Operation

DESCRIPTION
The control module has the following features:
^ Control module power is provided through control module harness Pins 1 and 21, Circuit 418 (DG/Y) and is protected by Fuse 4 (15A) in power distribution box and harness. Module ground is provided through control module wire harness Pin 32, Circuit 430 (GY) to the RH inner cowl panel sheet metal near the control module.
^ The connectors are keyed so that they cannot be installed incorrectly.

OPERATION
The air suspension/EVO control module has the following characteristics:
^ The air suspension system microprocessor and support hardware are contained in the control module. The control module constantly determines the height position of the vehicle body relative to the vehicle wheels. The system maintains a predetermined trim height regardless of road conditions or vehicle load.
^ The control module also uses vehicle speed to determine the proper trim height of the air suspension system. At approximately 105 km/h (65 mph), the suspension system lowers the vehicle trim for a more stable high speed profile.
^ The control module also controls the amount of power steering assist provided. This power steering assist is determined by the amount of change in the steering wheel rotation rate and vehicle speed.
^ The wiring harness connects to the control module using two separate push button release connectors.
^ The connectors are keyed so they cannot be installed incorrectly.
^ In general, the control module uses a 30-second averaging interval to determine when compress and vent operations are needed.
^ However, lamp switch inputs can override the 30-second averaging interval so compress and vent operations can begin immediately, if needed, after the doors are closed.
^ There are more restrictions on vent operations than there are on compress operations:
^ To eliminate the chance of catching a door on a curb as the vehicle vents down, the control module will not allow any venting to occur when a door is open.
^ The control module does not allow any vent operations for the first 30 seconds after the ignition switch has been turned to RUN. Even if a vehicle is extremely high at one corner, DO NOT expect it to vent until the ignition switch has been in RUN for 30 seconds.