DDEC III/IV Single ECM Troubleshooting – Section 10.11 Miscellaneous Digital Input Fault

Section 10.11
Miscellaneous Digital Input Fault

The following procedure will cover miscellaneous input switch faults. All faults function in the same manner, allowing the same troubleshooting process to be used regardless of the function.‪

There are 12 digital input cavities, listed in Table "Input Cavities" , available on a DDEC ECM. Any available function can be assigned (programmed with the Programming Station) to any of the available cavities. ‪

When a digital input wire is switched to battery ground (usually #953), it is a request to the ECM to activate the function assigned to that wire. Additional conditions may need to be met for the feature to activate. Refer to the appropriate Application and Installation manual for these conditions.‪

Input Cavities ‪	Input Cavities ‪
E1 #451‪	G2 #543‪
F1 #542‪	H2 #524‪
G1 #528‪	J2 #531‪
H1 #523‪	K2 #583‪
J1 #541‪	G3 #545‪
F2 #544‪	K3 #979‪

Available functions are listed in Table "Available Input Functions" .‪

Functions ‪	Functions ‪	Functions ‪
None‪	Limiting Torque Curve‪	Trans Retarder Status‪
Engine Brake Low‪	Diagnostic Request‪	Dual Throttle (LSG)‪
Engine Brake Med‪	Alt Min VSG/Fast Idle‪	A/C Fan Status‪
Aux Shutdown #1‪	Service Brake Release‪	Aux CLS‪
Aux Shutdown #2‪	Clutch Released‪	Fan Control Override‪
Park Brake / ISD‪	Set Coast OFF DDEC II‪	VSG Station Change‪
Idle Validation‪	Set / Coast ON‪	VSG Station Complement‪
Pressure / RPM Mode‪	Resume/Accel OFF DDEC II‪	Air Load Switch‪
Throttle Inhibit‪	Resume / Accel ON‪	In Neutral Switch‪
RPM Sync (Marine)‪	Cruise Enable‪	In Gear Switch‪
RPM Freeze (Marine)‪	PSG System Enable‪	KD Brake‪
Rating Switch #1‪	SEO / DIAG Request‪	Gas Valve Diagnostic‪
Rating Switch #2‪	Engine Brake Disable‪	-‪

Section 10.11.1
Verify Switch Status

Follow these steps to verify the switch status.‪

1. Turn ignition ON.
2. Plug in DDR.
3. Select switch light status.
4. Operate the engine or vehicle that would allow the feature to activate (e.g. activate switch, set brake, etc.).
5. Observe the status when the feature is active (or supposed to be active). See Figure "ECM Vehicle Harness Connector" .
   1. The feature always reads OFF. Refer to "10.11.2 Check for Open" .
   2. The feature switches from OFF to ON. Refer to "10.11.3 Review the Operation of the Feature" .
   3. The feature always reads ON. This indicates the input wire is shorted to ground or the switch is faulty. Repair wire or replace switch. Refer to "10.11.4 Verify Repairs" .
   

   Figure 1. ECM Vehicle Harness Connector

Section 10.11.2
Check for Open

Perform the following steps to check for an open circuit:‪

1. Turn ignition OFF.
2. Unplug the vehicle interface harness connector at the ECM.
3. Operate switch. Enable the feature.
4. Measure the resistance between the input cavity affected and the battery ground.
   1. If the measured resistance is greater than 10,000 Ω, the input wire or ground wire is open, or the switch is bad. Repair the break or replace the switch. Refer to "10.11.4 Verify Repairs" .
   2. If the measured resistance is less than 10,000 Ω, refer to "10.11.3 Review the Operation of the Feature" .

Section 10.11.3
Review the Operation of the Feature

Perform the following steps to check the operation of the feature:‪

1. The step that led you here indicates the input, wire, and switch, are operating correctly. Review the intended operation of the feature to determine if any other conditions need to be met for the feature to operate. (e.g. appropriate Application and Installation manual for the engine). Refer to "2.3 DDEC Related Publications" , for a list of related troubleshooting publications.
2. To verify the repairs to the feature, refer to "10.11.4 Verify Repairs" .

Section 10.11.4
Verify Repairs

Perform the following steps to verify repairs.‪

1. Hook up all connectors that were previously removed.
2. Operate the engine or vehicle.
3. Activate the feature.
   1. If the input feature operates correctly, troubleshooting is complete.
   2. If the input feature is not operating, contact Detroit Diesel Technical Service.