APPENDIX H -- INPUT/OUTPUT FUNCTIONS - TM-9-2320-303-24-10349

WTEC III ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL

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

WARNING!

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

(COMPRESSION BRAKE)

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.

VOCATIONS: Various

SWITCHED

ENGINE THROTTLE

POWER

SWITCH

ENGINE

V-3

COM

BRAKE

DASH

BRAKE

WIRE 132

LIGHT

OPTIONAL

ENGINE BRAKE

CUSTOMER-FURNISHED ENABLE OUPUT

VIM

ECU

VIW CONNECTOR(S)

Relay shown de-energized

WIRE 143H

NOTE: This switch is part of the engine brake system and

S-32

SIGNAL RETURN

provides an indication when the engine is at closed throttle.

This switch, or an equivalent control feature, is REQUIRED

ENGINE BRAKE

S S-26

for all installations.

DASH SWITCH

NOTE: The engine brake must provide a low engine speed

WIRE 169

shutoff feature, set to disable the brake at a speed slightly

ENGINE BRAKE AND

higher than idle rpm.

PRESELECT REQUEST

NOTE: If the engine brake is an inductive load, it must

be diode suppressed.

V04865

Figure H5. Engine Brake/Preselect Request and Engine Brake Enable (Compression Brake)

0021 00177