DDEC III/IV Single ECM Troubleshooting – Section 37.3 Troubleshooting Flash Code 37

Section 37.3
Troubleshooting Flash Code 37

The following procedure will troubleshoot Flash Code 37. ‪

Section 37.3.1
Multiple Code Check

Perform the following steps to check for multiple codes.‪

1. Turn ignition ON.
2. Plug the diagnostic data reader (DDR) into the diagnostic data link (DDL).
3. Read active codes.
   1. If active code 94/3 or 95/3 were logged, and no other codes were logged, refer to "37.3.2 Sensor Check" .
   2. If active codes 94/3 or 94/5 and any or all of the following codes were logged, 110/3 or 4, 174/3 or 4, 175/3 or 4, 101/3 or 4, 102/3 or 4, 100/3 or 4, 94/4, 73/3 or 4, refer to "90.1 Description of Engine Sensor Harness" .

Section 37.3.2
Sensor Check

Perform the following steps to check the sensor.‪

1. Turn ignition switch OFF.
2. Disconnect FPS/FRS connector. See Figure "Engine Harness Connector to Fuel Pressure Sensor" .
3. Turn ignition ON.
4. Start and run engine.
5. Select Engine Temperature (COOLANT TEMP & OIL) on DDR.
6. Warm up engine until engine temperature reading is greater than 60°C (140°F).
7. Leave engine running at idle after warm-up. Run for five minutes.
8. Read active codes.
   1. If active codes 94/3 or 95/3 and any other codes were logged, refer to "37.3.5 Check for Short" .
   2. If active code 94/4 and any other codes except 94/3 or 95/3 were logged, refer to "37.3.3 Return Circuit Check" .
   

   Figure 1. Engine Harness Connector to Fuel Pressure Sensor

Section 37.3.3
Return Circuit Check

Perform the following steps to check the return circuit.‪

1. Turn vehicle ignition OFF.
2. Disconnect the engine harness connector at the ECM.
3. Install a jumper wire between pins A and B of the FPS/FRS harness connector.
4. Measure resistance between sockets M1 and Y2 on the engine harness connectors.
   1. If resistance measurement is less than or equal to 5 Ω, refer to "37.3.4 Check Fuel Pressure Sensor Connectors" .
   2. If resistance measurement is greater than 5 Ω, or open, the return line (#452) is open. Repair the open and refer to "37.3.9 Verify Repairs" .

Section 37.3.4
Check Fuel Pressure Sensor Connectors

Perform the following steps to check the FPS/FRS connectors.‪

1. Inspect terminals at the FPS/FRS connectors (both the sensor and harness side) for damage: bent, corroded, and unseated pins or sockets.
   1. If the terminals and connectors are damaged, repair them and refer to "37.3.9 Verify Repairs" .
   2. If the terminals and connectors are not damaged, replace the FPS/FRS and refer to "37.3.9 Verify Repairs" .

Section 37.3.5
Check for Short

Perform the following steps to check for a short.‪

1. Turn ignition OFF.
2. Disconnect the engine harness connectors at the ECM.
3. Measure resistance between sockets W1 and M1 on the engine harness connector. See Figure "Engine Harness Connector to Fuel Pressure Sensor" .
   1. If the resistance measurement is greater than 100 Ω or open, refer to "37.3.6 Check for Short to Battery +" .
   2. If the resistance measurement is less than or equal to 100 Ω, the signal line (#905) is shorted to the engine +5 volt line (#416). Repair the short and refer to "37.3.9 Verify Repairs" .

Section 37.3.6
Check for Short to Battery +

Perform the following steps to check for a short to battery.‪

1. Remove both fuses to the ECM.
2. Disconnect the vehicle harness and 5-way power connectors at the ECM. See Figure "ECM Vehicle Harness Connector" .
3. Measure resistance between socket M1 on the engine harness connector and socket B3 of the vehicle harness connector, and between M1 and the 5-way power harness sockets A and C.
   1. If the resistance measurement is greater than 1,000 Ω or open, refer to "37.3.8 Check ECM Connector" .
   2. If the resistance measurement is less than or equal to 1,000 Ω, a short exists between sockets where less than 1,000 Ω was measured. Repair short and reinsert fuses. Refer to "37.3.9 Verify Repairs" .
   

   Figure 2. ECM Vehicle Harness Connector

Section 37.3.7
Final Check

Perform the following steps to do a final check.‪

1. Reconnect all connectors.
2. Turn vehicle ignition ON.
3. Clear codes.
4. Start and run the engine for one minute.
5. Stop engine.
6. Check DDR for codes.
   1. If no codes are logged, troubleshooting is complete.
   2. If active codes 94/3 or 95/3 are logged, reprogram the ECM. Refer to "37.3.9 Verify Repairs" .
   3. If any codes except codes 94/3 or 95/3 are logged, refer to "9.1 First Step for Diagnosing a Fault Within the DDEC System" .

Section 37.3.8
Check ECM Connector

Perform the following steps to check the ECM connector.‪

1. Inspect terminals at the ECM connector (both the ECM and harness side) for damage: bent, corroded, and unseated pins or sockets.
   1. If terminals and connectors are damaged, repair them. Refer to "37.3.9 Verify Repairs" .
   2. If terminals and connectors are not damaged, replace the FPS/FRS. Refer to "37.3.7 Final Check" . see Figure "Fuel Restriction Sensor Installation" .
      

      Figure 3. Fuel Restriction Sensor Installation

Section 37.3.9
Verify Repairs

Perform the following steps to verify repairs.‪

1. Turn ignition switch OFF.
2. Reconnect all connectors.
3. Turn ignition ON.
4. Clear codes.
5. Start and run the engine for one minute.
6. Stop engine.
7. Check DDR for codes.
   1. If no codes are logged, no further troubleshooting is required.
   2. If codes 94/3 or 95/3 are not logged, and other codes are logged, refer to "9.1 First Step for Diagnosing a Fault Within the DDEC System" .
   3. If codes 94/3 or 95/3 are logged, and other codes are logged, all system diagnostics are complete. Please review this section from the first step to find the error. Refer to "37.3.1 Multiple Code Check" .