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.
Exhaust Back Pressure Failed High
Follow these steps to troubleshoot exhaust back pressure failed high:
- Disconnect Exhaust Back Pressure Sensor.
- Start and run the engine.
- Check codes displayed.
Check for Short to +5 Line
Follow these steps to check for a short to the +5 volt line:
- Unplug the ECM/ECU vehicle connector.
- Measure resistance between cavities B and C.
Check for Open
Perform the following steps to check for open:
- Install jumper between cavities V–60 and V–11.
- Measure resistance between cavities A and B of the EBP Sensor connector.
Perform the following steps to check the connectors:
- If connectors are not damaged, replace the Exhaust Back Pressure Sensor. Refer to "188.8.131.52 Verify Repairs" .
- If the connectors are corroded, bent, or damaged, repair or replace them. Refer to "184.108.40.206 Verify Repairs" .
Perform the following steps to verify repairs.
- Turn ignition switch OFF and reconnect all connectors.
- Turn ignition ON and clear codes.
- Start and run the engine for one minute.
- Stop the engine and check diagnostic tool for codes.
- If no codes are logged, no further troubleshooting is required.
- 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" .
- If code p 81/3 and other codes are logged, review this section from the first step to find the error. .
|Series 60 DDEC V Troubleshooting Guide - 6SE570|
|Generated on 10-13-2008|