Copyright © 1998 General Motors Corp.
P–9
W T E C I I E L E C T RO N I C C O N T RO L S T RO U B L E S H O OT I N G M A N UA L
APPENDIX P — INPUT/OUTPUT FUNCTIONS
WARNING!
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
(STANDARD)
USES:
Used with engine 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 second range for exhaust style brakes and fourth
range for compression style brakes.
VOCATIONS:
Various
Figure P–9. Engine Brake/Preselect Request and Engine Brake Enable (Standard)
E2
NC
COM
VIM
ENGINE BRAKE
DASH SWITCH
DASH
LIGHT
ENGINE THROTTLE
ENABLE SWITCH
Relay shown de-energized
SWITCHED
POWER
ENGINE
BRAKE
NO
D2
V05014
BRAKE
ON
NOTE: This switch is part of the engine brake system and
provides an indication when the engine is at closed throttle.
This switch, or an equivalent control feature, is REQUIRED
for all installations.
NOTE: The engine brake must provide a low engine speed
shutoff feature, set to disable the brake at a speed slightly
higher than idle rpm.
WIRE 119
ENGINE BRAKE AND
PRESELECT REQUEST
WIRE 132
ENGINE BRAKE ENABLE OUPUT
3
VIW
CONNECTOR
ECU
