TM 9-2320-363-20-1
Section 3
TESTING THE DDEC III SYSTEM (Cont'd.)
For more information on how to change these features, refer to the DDR Instruction Manual..
F. CONNECTOR CHECKOUT
All system connections are environmentally protected These connectors protect the terminations form the harsh corrosive
engine compartment environment. This is important since most system signals are low voltage and corrosion could make
them inoperative.
Before repairing or replacing any system component (i e., harness, sensor, ECM, etc.) as indicated by the diagnostic
charts, you should:
1.
Disconnect the appropriate connector(s) associated with the suspected defective component and check for bent,
broken, or dirty terminals or mating tabs. Clean, straighten, or replace as required.
2.
If a problem was found, reconnect all connectors previously disconnected. Then recheck the system to see if the
problem has been corrected.,
NOTE:
Don't probe the back of a connector or pierce the DDEC III wiring for purposes of
taking measurement. This can cause intermittent faults or system failures and
may affect the engine warranty.
G. DIGITAL INPUT/OUTPUT FUNCTIONS
DDEC 3 provides twelve discrete input pins on the vehicle harness which may be customized to the customer application.
A discrete input function is selected by its "function number" and assigned to a pin number on the 30-pin vehicle harness
connector. When battery ground is supplied to the pin number, the ECM performs the function defined by the discrete
input selected. No function should be assigned to more than one pin (except FUNCTION #0 -- No Function).
Examples:
1.
Pin H2 of the ECM's 30-pin vehicle harness connector has FUNCTION #9 (Throttle Inhibit) assigned it. When
battery ground is supplied to pin H2, the foot pedal input is disabled preventing engine operation above idle
speed.
2.
Pin K3 and K2 of the ECM's 30-pin vehicle harness connector have FUNCTION #1 (Engine Brake Low) and
FUNCTION #2 (Engine Brake Medium), respectively, assigned to them. When battery ground is supplied to pin
K3, the low setting of the engine brake is achieved. When battery ground is supplied to pin K2, the medium
setting is achieved. If both pins are grounded simultaneously, the high setting for engine braking is achieved.
(Note: In this example, Engine brakes must have been configured when the engine was ordered)
DIGITAL OUTPUTS
DDEC3 provides three discrete output pins on the vehicle harness which may be customized to the customer application.
These outputs provide a ground (less than 0.8 volts with respect to DDEC ground) capable of sinking up to 1 ampere of
DC current when the output Is active.
Change 3 3-345.17
