DDEC III/IV Single ECM Troubleshooting – Section 81.3 Troubleshooting Flash Code 81

Section 81.3
Troubleshooting Flash Code 81

The following procedure will troubleshoot Flash Code 81. For code s 155 or 411, refer to "81.3.1 Check for Open" ; for code s 154 or 412, refer to "81.3.3 Check for Open" .‪

For troubleshooting code 98/3, refer to "81.4.1 Multiple Code Check" .‪

For troubleshooting code p 173/3, exhaust gas temperature circuit failed high, refer to "81.5.1 Check for Open" .‪

Section 81.3.1
Check for Open

Perform the following steps to check for an open. ‪

1. Unplug the engine sensor harness 30–pin connector.
2. Unplug the EGR Delta-Pressure sensor.
3. Install a jumper wire between cavities Y2 and M2 at the EGR  Delta-Pressure sensor. See Figure "EGR  Delta-Pressure Sensor Wiring" .
   

   Figure 1. EGR  Delta-Pressure Sensor Wiring

4. Measure resistance between P/N: 23527349, Series 60 or Series 50 – cavity 1 and 2. Measure resistance between P/N: 23531964, – cavity 2 and 3. See Figure "EGR  Delta-Pressure Sensor Wiring" .
   1. If the resistance measurement is less than or equal to 5 Ω, Refer to "81.3.2 Check for Short" .
   2. If the resistance measurement is greater than 5 Ω, circuit #452 is open. Repair and verify. Refer to "81.3.5 Verify Repair" .

Section 81.3.2
Check for Short

Perform the following steps to check for short: ‪

1. Remove the jumper wire.
2. Measure resistance between P/N: 23531964 or Series 50 – cavity 1 and 3. Measure resistance between P/N: 23527349 – cavity 2 and 3. See Figure "EGR  Delta-Pressure Sensor Wiring" .
   1. If the resistance measurement is less than 1.5 k Ω, circuit #416 is shorted to #958. Repair and verify. Refer to "81.3.5 Verify Repair" .
   2. If the resistance measurement is equal to 1.5 k Ω, replace the EGR sensor and go to "81.3.5 Verify Repair" .

Section 81.3.3
Check for Open

Perform the following steps to check for an open. ‪

1. Disconnect the EGR temperature sensor.
2. Install a jumper wire between cavities A and B. See Figure "EGR Temperature Sensor Wiring" .
   

   Figure 2. EGR Temperature Sensor Wiring

3. Disconnect the engine sensor harness 30–pin connector.
4. Measure resistance between R1 and Y2. See Figure "EGR Temperature Sensor Wiring" .
   1. If the resistance measurement is less than or equal to 5 Ω, Refer to "81.3.4 Check for Short" .
   2. If the resistance measurement is greater than 5 Ω, circuit #907 or #452 is open. Repair and verify. Refer to "81.3.5 Verify Repair" .

Section 81.3.4
Check for Short

Perform the following steps to check for short:‪

1. Remove jumper wire.
2. Measure resistance between W1 and R1. See Figure "EGR Temperature Sensor Wiring" .
   1. If the resistance measurement is less than 1.5 k Ω, circuit #416 is shorted to #907. Repair and verify. Refer to "81.3.5 Verify Repair" .
   2. If the resistance measurement is greater than 1.5 k Ω, the resistor has failed. Repair and verify. Refer to "81.3.5 Verify Repair" .
   3. If the resistance measurement is equal to 1.5 k Ω, replace the EGR temperature sensor.

Section 81.3.5
Verify Repair

Perform the following steps to verify repairs.‪

1. Connect all connectors.
2. Start and run the engine.
3. Road test the engine.
   1. If code 81 was not logged, no further troubleshooting is required.
   2. If code 81 was logged, please review this section from the first step to find the error. Refer to "81.3.1 Check for Open" . If this is the second time through the procedure, call Detroit Diesel Technical Service, or try a test ECM.