Series 60 DDEC V Troubleshooting – Section 72.2 Troubleshooting Flash Code 77, PID 81, FMI 3

Section 72.2
Troubleshooting Flash Code 77, PID 81, FMI 3

Flash Code 77, p 81/3 is exhaust back pressure failed high. ‪

• The code is used to determine if high fuel temperature may be a cause of reduced power levels.
• High fuel temperature will reduce available horsepower.
• Refer to the recommendations of the vehicle manufacturer regarding the possible need for additional fuel cooling.

Section 72.2.1
Exhaust Back Pressure Failed High

Follow these steps to troubleshoot exhaust back pressure failed high:‪

1. Disconnect Exhaust Back Pressure Sensor.
2. Start and run the engine.
3. Check codes displayed.
   1. If code p 81/3 displays, refer to "72.2.2 Check for Short to +5 Line" .
   2. If code p 81/4 displays, refer to "72.2.4 Check Connectors" .

Section 72.2.2
Check for Short to +5 Line

Follow these steps to check for a short to the +5 volt line:‪

1. Unplug the ECM/ECU vehicle connector.
2. Measure resistance between cavities B and C.
   1. If the resistance measures greater than 5 Ω, refer to "72.2.3 Check for Open" .
   2. If the resistance measures less than 5 Ω, wire #916 is shorted to #510. Repair the short and refer to "72.2.4.1 Verify Repairs" .

Section 72.2.3
Check for Open

Perform the following steps to check for open: ‪

1. Install jumper between cavities V–60 and V–11.
2. Measure resistance between cavities A and B of the EBP Sensor connector.
   1. If measured resistance is less than 50 Ω, refer to "72.2.4 Check Connectors" .
   2. If measured resistance is greater than 50 Ω, wire V-60 is open. Repair the open and refer to "72.2.4.1 Verify Repairs" .

Section 72.2.4
Check Connectors

Perform the following steps to check the connectors: ‪

1. If connectors are not damaged, replace the Exhaust Back Pressure Sensor. Refer to "72.2.4.1 Verify Repairs" .
2. If the connectors are corroded, bent, or damaged, repair or replace them. Refer to "72.2.4.1 Verify Repairs" .

Section 72.2.4.1
Verify Repairs

Perform the following steps to verify repairs.‪

1. Turn ignition switch OFF and reconnect all connectors.
2. Turn ignition ON and clear codes.
3. Start and run the engine for one minute.
4. Stop the engine and check diagnostic tool for codes.
   1. If no codes are logged, no further troubleshooting is required.
   2. If codes p 81/3 was not logged, and other codes are logged, refer to "18.3 First Step for Diagnosing a Fault Within the DDEC System" .
   3. If code p 81/3 and other codes are logged, review this section from the first step to find the error. .