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TM 9-2320-360-20-3
Section 3
TESTING THE DDEC iii SYSTEM (Cont’d)
D. CLEARING CODES
This can only be done using the Diagnostic Data Reader (DDR). Refer to the DDR Instruction Manual for details.
Note that removing the battery cables will not clear codes.
E. CONNECTOR CHECKOUT
All system connections are environmentally protected. These connectors protect the terminations from the harsh corrosive
engine compartment environment. This is important since mostsystem 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 Ill wiring for purposes of taking measurement. This can cause
intermittent faults or system failures and may affect the engine warranty.
F. DIGITAL INPUT/OUTPUT FUNCTIONS
DIGITAL OUTPUTS
DDEC Ill 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.
The function may be selected by its “function number” found in the list below. No function should be assigned to more than one
pin (except FUNCTION #0 - No Function).
Examples:
1. Pin J3 of the ECM’s 30-pin vehicle harness connector has the transmission modulator function assigned to it. This
function causes the DDEC ECM to provide a ground to activate the transmission modulator relay (R30) whenever the
transmission modulator should be activated. This function turns on whenever the TPS value exceeds 80%, and turns
off when the TPS value drops below 60%.
2. Pin Al of the ECM’s 30-pin vehicle harness connector has the engine brake function assigned to it. This function
causes the DDEC ECM to provide a ground to activate the engine brake relay (R15) under those conditions when the
engine brakes can be used. This function occurs under no-fuel conditions (TPS value = 0%) and when the engine
speed is greater than 1000 RPM.
H-13/(H-14blank)
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