Section 5.4
Fuel-Related Electronic Fault Codes
Below are common flash codes related to the unit injector and fuel system:
Section 5.4.1
FLASH CODE 37 - FUEL PRESSURE SENSOR/FUEL RESTRICTION SENSOR VOLTAGE HIGH
Flash Code 37 indicates that the engine Fuel Pressure Sensor, or Fuel Restriction Sensor input to the ECM has exceeded 95% (normally > 4.75 volts) of the sensor supply voltage. The SAE J1587 equivalent code for Flash Code 37 is PID 94-FMI 3, Fuel Pressure Sensor, and PID 95-FMI 3, Fuel Restriction Sensor. Refer to MBE 900 service manual (6SE414) or MBE 4000 service manual (6SE412) for complete testing procedures.
This diagnostic condition is typically:
- Open sensor return circuit
- Sensor signal circuit is shorted to the sensor +5 volt supply
Section 5.4.2
FLASH CODE 38 - FUEL PRESSURE SENSOR/FUEL RESTRICTION SENSOR VOLTAGE LOW
Flash Code 38 indicates that the Engine Fuel Pressure Sensor, and/or, Fuel Restriction Sensor input to the ECM has dropped below 5% (normally < 0.25 volts) of the sensor supply voltage. The SAE J1587 equivalent code for Flash Code 38 is PID 94-FMI 4, Fuel Pressure Sensor, and PID 95-FMI 4, Fuel Restriction Sensor. Refer to MBE 900 service manual (6SE414) or MBE 4000 service manual (6SE412) for complete testing procedures.
This diagnostic condition is typically:
- Open sensor signal circuit
- Open sensor +5 volt supply circuit
- Sensor signal is shorted to sensor return circuit or to ground
- Sensor +5 volt supply is shorted to the sensor return circuit
Section 5.4.3
FLASH CODE 47 - AIR/FUEL PRESSURE HIGH
Flash Code 47 indicates that the ECM has detected that the turbo boost pressure has exceeded a programmed operating range. This normally occurs due to a mechanical fault in the air system or fuel system of the engine. The SAE J1587 equivalent code for Flash Code 47 is PID 94-FMI 0, fuel pressure high, PID102-FMI 0, turbo boost pressure high, PID 106-FMI 0, air inlet pressure high, and PID 164-FMI 0, injection control pressure high. This code indicates a mechanical fault. Check for reasons for high turbo boost pressure, e.g. Variable Nozzle Turbocharger (VNT) stuck. Refer to MBE 900 service manual (6SE414) or MBE 4000 service manual (6SE412) for complete testing procedures.
Section 5.4.4
FLASH CODE 48 - AIR/FUEL PRESSURE LOW
Flash Code 48 indicates that the ECM has detected that the fuel pressure has dropped below a programmed limit. This condition is normally associated with a restriction in the fuel supply system. The SAE J1587 equivalent code for Flash Code 48 is PID 094-FMI 1, fuel pressure low, PID 106-FMI 1, air inlet pressure low, and PID 164-FMI 1, injection control pressure low. Refer to MBE 900 service manual (6SE414) or MBE 4000 service manual (6SE412) for complete testing procedures.
This diagnostic condition is typically:
- Plugged fuel filter
- Low fuel supply
Section 5.4.5
FLASH CODE 61 - INJECTOR RESPONSE TIME LONG
Flash Code 61 indicates that the time it takes from when the DDEC ECM requests an injector to be turned on to when the injector solenoid valve actually closes is longer than the high limit of the expected range. Engine oil temperature must be greater than 87°F (30°C). The SAE J1587 equivalent code for Flash Code 61 is SID 001/0, or SID 002/0, or SID 003/0, or SID 004/0, or SID 005/0, or SID 006/0.
This diagnostic condition is typically:
- Bad injector harness and or connection (high resistance)
- Poor vehicle grounds
- Sticky solenoid valve
- Injector failure
- Bad stator
Note: The injector diagnostic SID (Subsystem Identifier) indicates which cylinder number has an injector with a long response time. The injector number describes the cylinder and or bank, which has the injector with a long response time.
Injector response times generally increase with low battery supply voltage and decrease with high battery supply voltage. Although injector response times vary from injector to injector at a given rpm, each individual injector response time should remain relatively consistent from one firing to the next. Wide variations in response time (typically ± 0.2 msec) for one injector at a steady engine rpm may indicate an electrical problem (faulty alternator or voltage regulator, poor or broken ground cables, etc.).
Section 5.4.6
FLASH CODE 71 - INJECTOR RESPONSE TIME SHORT
Flash Code 71 indicates that the time it takes from when the DDEC ECU requests an injector be turned on, to when the injector valve actually closes, is shorter than the lower limit of the expected range. The SAE J1587 equivalent code for Flash Code 71 is SID 001/1, or SID 002/1, or SID 003/1, or SID 004/1, or SID 005/1, or SID 006/1.
This diagnostic condition is typically:
- Aerated fuel system
- High system battery (+) supply voltage
- Injector failure
- Failed solenoid
Section 5.4.7
Flash Code 77 - ISOLATED FUEL
Flash Code 77 is used for several DDEC information codes. The fuel related code descriptions are listed below:
- PID 95-FMI 1 is a fuel filter differential pressure below range. Fuel filter differential pressure sensor signal fell below calibrated limit. Not likely to show up on any DDEC IV on-highway engines.
- PID 174-FMI 0 is a fuel temperature above range. Indicates fuel temperature exceeded DDC limits for that particular engine. No DDEC troubleshooting is suggested. High fuel temperature should be reviewed with the OEM to determine if any additional fuel coolers need to be considered.
- PID 174-FMI 1 is a fuel temperature below range. Indicates the fuel temperature fell below a calibrated range. No troubleshooting is suggested.
| Unit Fuel Injectors and Unit Pumps Technician's Guide - 7SE500 |
| Generated on 10-13-2008 |