Series 60 DDEC V Troubleshooting – Section 79.1 Troubleshooting the Engine Harness

Section 79.1
Troubleshooting the Engine Harness

Referral to this section indicates a fault within the Engine Harness (see the Figure 45699 on the previous page) affecting signals of various sensors used by the DDEC system.‪

The following procedure will troubleshoot the Engine Harness.‪

Section 79.1.1
Check for Low Battery Voltage

Perform the following steps to check for low battery voltage.‪

1. Plug in the diagnostic tool.
2. Check for codes.
   1. If Flash Code p 168/1 is logged, refer to "49.2 Troubleshooting Flash Code 46, PID 168/FMI 1" .
   2. If code p 168/1 is not logged, refer to "79.1.2 Check for +5 Volts" .

Section 79.1.2
Check for +5 Volts

Perform the following steps to check for +5 volts.‪

1. Turn vehicle ignition switch OFF.
2. Disconnect the Oil Pressure Sensor/Engine Oil Pressure Sensor (OPS/EOP Sensor) and Turbo Boost Sensor/Intake Manifold Pressure Sensor (TBS/IMP Sensor) connectors.
3. Turn vehicle ignition switch ON.
4. At each sensor harness connector, measure voltage between socket E–12 (red lead-socket 3) and socket E–15 (black lead-socket 1).
   1. If the voltage measurement is between 4.7 and 5.2 volts, the voltage reading is correct. Check voltage at the next connector. If all connector voltage readings are correct, refer to "79.1.3 Check ECM/ECU Connectors" .
   2. If the voltage measurement is less than 4.7 volts at any or all connectors, refer to "79.1.4 Check for +5 volts or Return Open" .
   3. If the voltage measurement is greater than 5.2 volts at all connectors, refer to "79.1.6 Check for Short to Battery" .

Section 79.1.3
Check ECM/ECU Connectors

Perform the following steps to check the ECM/ECU connectors.‪

1. Check terminals at the ECM/ECU engine harness connector (both the ECM/ECU and harness side) for damaged, bent, corroded and unseated pins or sockets.
   1. If the terminals and connectors are not damaged, go to step 2 .
   2. If the terminals and connectors are damaged, repair them. Refer to "79.1.6.1 Verify Repairs" .
2. Check all sensors, especially OPS/EOP Sensor, TBS/IMP Sensor, and TPS/AP Sensor (on vehicle system), this indicates that there is no problem on the Engine Harness. Refer to "80 Vehicle Interface Harness" .

Section 79.1.4
Check for +5 volts or Return Open

Perform the following steps to check for +5 volts or return open.‪

1. Turn vehicle ignition switch OFF.
2. Disconnect the engine harness connector at the ECM/ECU.
3. Install a jumper wire between sockets 1 and 3 of any sensor connector that reads less than 4.7 volts. Refer to "79.1.2 Check for +5 Volts" .
4. Measure resistance between sockets E-12 and E-15 of the engine harness connector.
   1. If the resistance measurement is less than or equal to 5 Ω, refer to "79.1.5 Check for Short to Ground" .
   2. If the resistance measurement is greater than 5 Ω or open, either the engine +5 volt line (E-12) or the return line (E-15) is open. Repair the open and refer to "79.1.6.1 Verify Repairs" .

Section 79.1.5
Check for Short to Ground

Perform the following steps to check for short to ground.‪

1. Turn vehicle ignition switch OFF.
2. Remove jumper wire.
3. Measure resistance between sockets 1 and 3 of the sensor connector.
4. Measure resistance between socket C of the sensor connector and a good ground.
   1. If the resistance measurement for both readings is greater than 1,000 Ω, or open, refer to "79.1.3 Check ECM/ECU Connectors" .
   2. If either resistance measurement is less than or equal to 1,000 Ω, the engine +5 volt line (E-12) is shorted to either the sensor return line (E-15) or to chassis ground. Repair the short and refer to "79.1.6.1 Verify Repairs" .

Section 79.1.6
Check for Short to Battery

Perform the following steps to check for a short to battery.‪

1. Turn vehicle ignition switch OFF.
2. Remove both fuses to the ECM/ECU.
3. Disconnect both connectors at the ECM/ECU.
4. Measure resistance between socket E-12 on the engine harness connector and V-15 on the vehicle harness connector.
5. Measure resistance between socket E-12 on the engine harness connector and the battery (+).
   1. If the resistance measurement for both readings is greater than 1,000 Ω, or open, refer to "79.1.3 Check ECM/ECU Connectors" .
   2. If either resistance measurement is less than or equal to 1,000 Ω, a short exists between sockets where reading was taken. Repair the short and refer to "79.1.6.1 Verify Repairs" .

Section 79.1.6.1
Verify Repairs

Perform the following steps to verify repairs.‪

1. Turn vehicle ignition switch OFF.
2. Reconnect all connectors.
3. Reconnect fuses (or circuit breakers) if previously disconnected.
4. Turn ignition ON.
5. Clear codes.
6. If Amber Warning Lamp (CEL/AWL) does not stay on, start engine and run for one minute.
7. Stop engine.
8. Read inactive codes with the diagnostic tool.
   1. If no codes are logged, troubleshooting is complete.
   2. If codes that brought you to this section are still logged, all system diagnostics are complete. Review this section from the first step to find the error. Refer to "79.1.1 Check for Low Battery Voltage" .
   3. If codes except those which brought you to this section are logged, refer to "18.3 First Step for Diagnosing a Fault Within the DDEC System" .