DDEC III/IV Single ECM Troubleshooting – Section 82.5 Troubleshoot Exhaust Gas Temperature

Section 82.5
Troubleshoot Exhaust Gas Temperature

Follow these procedures to troubleshoot exhaust gas temperature: ‪

Section 82.5.1
Check for Open

Typically, the exhaust gas temperature circuit failed high is caused by an open signal or short to battery+. Perform the following steps to troubleshoot code p 173/3:‪

1. For low volt code (82) disconnect the ETS connector.
2. Install a jumper wire between the two pins at the ETS.See Figure "Exhaust Temperature and Pressure Sensor Wiring Schematic" .
3. Unplug both 30–pin connectors at the ECM. See Figure "Exhaust Temperature and Pressure Sensor Wiring Schematic" .
4. Measure resistance between D3 of the VIH connector and W1 of the ESH connector. See Figure "Exhaust Temperature and Pressure Sensor Wiring Schematic" .
   1. If resistance measures < 5 Ω, refer to "82.5.2 Check for Short" .
   2. If resistance is > 5 Ω, either the circuit #416 is opened, or #749 is opened. Repair the open or replace the wire and test. Refer to "82.5.4 Test" .

Figure 1. Exhaust Temperature and Pressure Sensor Wiring Schematic

Section 82.5.2
Check for Short

Perform the following steps to check for a short: ‪

1. Remove the jumper.
2. Measure resistance again between D3 and W1. See Figure "Exhaust Temperature and Pressure Sensor Wiring Schematic" .
   1. If the reading is > 400 Ω, the resistor between circuit #416 and #749 has failed. Replace the resistor or replace the harness.
   2. If the reading is < 400 Ω, replace the ETS, and refer to "82.5.3 Check for Short to Ground" .

Section 82.5.3
Check for Short to Ground

Perform the following steps to check for short to ground:‪

1. Measure the resistance between cavity #D3 and ground (battery and block). See Figure "Exhaust Temperature and Pressure Sensor Wiring Schematic" .
2. Measure the resistance between cavity #W1 and ground (battery and block).
   1. If any readings are less than 5 Ω, that wire is shorted to ground. Repair or replace the wire and test. Refer to "82.5.4 Test" .
   2. If both readings are greater than 5 Ω, replace ETS and test. Refer to "82.5.4 Test" .

Section 82.5.4
Test

Perform the following steps to test the repair:‪

1. Connect all removed connectors.
2. Start and run the engine.
3. Perform road test.
4. Plug in DDR and read active codes.
   1. If no codes display, repairs are complete.
   2. If code 81 displays, review the procedure for checking exhaust gas temperature circuit failed high; refer to "82.5.1 Check for Open" . If this is the second time through the procedure, call DDC Technical Service, or try a test ECM.