APPENDIX H -- INPUT/OUTPUT FUNCTIONS - TM-9-2320-303-24-10350

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

(EXHAUST BRAKE -- SPECIAL)

USES: Used with engine brakes to provide a signal to 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.

VOCATIONS: Various

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

provides an indication when the engine is at closed throttle.

SWITCHED

This switch, or an equivalent control feature, is REQUIRED

POWER

for all installations.

NOTE: The engine brake must provide a low engine speed

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

WIRE 132

higher than idle rpm.

V-3

ENGINE BRAKE

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

ENGINE BRAKE

ENABLE OUPUT

suppressed.

DASH SWITCH

OPTIONAL

ENGINE THROTTLE

CUSTOMER-FURNISHED

ECU

SWITCH

VIW CONNECTOR(S)

WIRE 119

S-11

ENGINE BRAKE AND

COM

ENGINE

DASH

BRAKE

PRESELECT REQUEST

BRAKE

LIGHT

VIM

Relay shown de-energized

V04867

Figure H6. Engine Brake/Preselect Request and Engine Brake Enable (Exhaust Brake -- Special)

0021 00178