DDEC III/IV Single ECM Troubleshooting – Section 18.3 Troubleshooting Flash Code 18, Throttle Valve Plate Input Voltage

Section 18.3
Troubleshooting Flash Code 18, Throttle Valve Plate Input Voltage

The following procedure will troubleshoot Flash Code 18.‪

Section 18.3.1
Check Actuator

Perform the following steps to check the actuator.‪

1. Unplug throttle actuator harness connector.
2. Install a jumper wire between cavity F and C. See Figure "Gas Engine Sensor Harness" .
3. Turn ignition ON.
4. Plug in DDR. Read the codes.
   1. If code p 051/3 and any other codes are logged, refer to "18.3.2 Check Connectors" .
   2. If code p 051/4 is logged, refer to "18.3.3 Check for Open" .

Figure 1. Gas Engine Sensor Harness

Section 18.3.2
Check Connectors

Perform the following steps to check the connectors.‪

1. Turn ignition OFF.
2. Remove jumper wire.
3. Check connectors, both ECM and throttle actuator side, for bent, broken, or loose connections.
   1. If the connectors are not damaged, replace the actuator and refer to "18.3.6 Verify Repairs" .
   2. If the connectors are damaged, bent or have broken pins, repair or replace them. Refer to "18.3.6 Verify Repairs" .

Section 18.3.3
Check for Open

Perform the following steps to check for open.‪

1. Turn ignition OFF.
2. Move jumper wire from cavity F and C to cavity F and D. See Figure "Gas Engine Sensor Harness" .
3. Remove engine harness connector.
4. Measure resistance between Y2 (#452) and R1 (#907). See Figure "Gas Engine Sensor Harness" .
   1. If the measured resistance is greater than 1,000 Ω, wire #907 is open. Repair the open or replace the harness and refer to "18.3.6 Verify Repairs" .
   2. If the measured resistance is less than 1,000 Ω, refer to "18.3.4 Check for Short to Return" .

Section 18.3.4
Check for Short to Return

Perform the following steps to check for a short to the return line.‪

1. Remove jumper.
2. Measure resistance between Y2 (#452) and R1 (#907), and Y2 (#452) and W1 (#416). See Figure "Gas Engine Sensor Harness" .
   1. If either measured resistance is less than 1,000 Ω, those wires are shorted to each other. Replace the harness and refer to "18.3.6 Verify Repairs" .
   2. If both measured resistance are greater than 1,000 Ω, refer to "18.3.5 Check for Short to Battery (-)" .

Section 18.3.5
Check for Short to Battery (-)

Perform the following steps to check for a short to the battery (-).‪

1. Measure resistance between R1 (#907) and battery ground, and W1 (#416) and battery ground. See Figure "Gas Engine Sensor Harness" .
   1. If either measured resistance is less than 1,000 Ω, then that wire is shorted to the battery (-). Replace the harness and refer to "18.3.6 Verify Repairs" .
   2. If the measured resistance is greater than 1,000 Ω, refer to "18.3.7 Check for 5–Volt Open" .

Section 18.3.6
Verify Repairs

Perform the following steps to verify repairs.‪

1. Plug all connectors in.
2. Start and run the engine.
3. Plug in the DDR and read the codes.
   1. If no codes are logged, troubleshooting is complete.
   2. If code p 051/4 is logged, please review this section from the first step to find the error. Refer to "18.3.1 Check Actuator" . Then, contact Detroit Diesel Technical Services.

Section 18.3.7
Check for 5–Volt Open

Perform the following steps to check for a 5–volt open.‪

1. Plug in the 30-pin connector for the engine sensor harness.
2. Turn ignition ON.
3. Measure voltage between cavity D (#452) and C (#416) of the actuator connector. See Figure "Gas Engine Sensor Harness" .
   1. If the measurement is less than 4.5 volts, wire #416 is open. Repair the open or replace the harness. Refer to "18.3.6 Verify Repairs" .
   2. If the measurement is between 4.5 and 5.5 volts, refer to "18.3.2 Check Connectors" .