W T E C I I I E L E C T R O N I C C O N T R O L S T R O U B L E S H O O T I N G M A N U A L
APPENDIX H INPUT/OUTPUT FUNCTIONS
These schematics show the intended use of the specified controls features which
have been validated in the configuration shown. Any miswiring or use of these
features which differs from that shown could result in damage to equipment or
property, personal injury, or loss of life. ALLISON TRANSMISSION IS NOT
LIABLE FOR THE CONSEQUENCES ASSOCIATED WITH MISWIRING
OR UNINTENDED USE OF THESE FEATURES.
ENGINE BRAKE/PRESELECT REQUEST AND ENGINE BRAKE ENABLE
USES: Used with single-level compression brakes to signal the ECU that the brake is active and to provide
increased braking by preselecting a lower range. Also prevents engagement of engine brake with
throttle > 0 or lockup OFF.
VARIABLES TO SPECIFY:
Preselect range. Standard value is fourth range.
Figure H5. Engine Brake/Preselect Request and Engine Brake Enable (Compression Brake)