P0237 MAP SENSOR VOLTAGE TOO LOW

When Monitored and Set Condition:

When Monitored: With the ignition on and battery voltage greater than 10.4 volts.
Set Condition: The circuit voltage to the ECM falls below a calibrated threshold for a certain period of time.

POSSIBLE CAUSES

• OTHER DTC'S
• (K68) SIGNAL CIRCUIT SHORTED TO (Y502) SENSOR RETURN CIRCUIT
• (Y501) 5-VOLT SUPPLY CIRCUIT SHORTED TO (Y502) SENSOR RETURN CIRCUIT
• MAP SENSOR
• (K68) SIGNAL CIRCUIT OPEN
• (Y501) 5-VOLT SUPPLY CIRCUIT OPEN
• MAP SENSOR (K68) SIGNAL CIRCUIT SHORT TO GROUND
• ECM

DIAGNOSTIC PROCEDURE

NOTE: Refer to VERIFICATION TESTS for appropriate verification test procedures.

1. Turn the ignition on. With the DRBIII®, read the Engine DTC's. Is there a 5-volt Supply DTC set?
   Yes --> Refer to symptom list for problems related to the 5-volt Supply DTC. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 2
2. Turn the ignition off. Disconnect the Map sensor harness connector. Check connectors - Clean/repair as necessary. Turn the ignition on. Measure the voltage between the (Y501) 5-volt supply circuit and sensor (Y502) return circuit of the Map sensor harness connector. Is the voltage between 4.5 and 5.5 volts?
   Yes --> Go To 3
   No --> Go To 4
3. While monitoring the DRBIII®, jumper the (Y501) 5-volt supply circuit to the (K68) signal circuit in the Map sensor harness connector. Did the P0238-MAP SENSOR VOLTAGE TOO HIGH, DTC set?
   Yes --> Replace the MAP sensor. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 4
4. Turn the ignition off. Disconnect the ECM harness 60 pin connector. Check connectors - Clean/repair as necessary. Measure the resistance between the (K68) signal circuit and (Y502) sensor return circuit in the MAP sensor harness connector. Is the resistance greater than 100 K Ohms?
   Yes --> Repair (K68) signal circuit shorted to (Y502) sensor return circuit or replace harness. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 5
5. Measure the resistance between the (Y501) 5-volt supply circuit and (Y502) sensor return circuit in the MAP sensor harness connector. Is the resistance greater than 100 K Ohms?
   Yes --> Repair (Y501) 5-volt supply circuit shorted to (Y502) sensor return circuit or replace harness. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 6
6. Measure the resistance between the signal (K68) circuit in the Map sensor harness connector with the (K68) signal circuit in the ECM harness connector. Is the resistance less than 10 Ohms?
   Yes --> Go To 7
   No --> Repair or replace the engine harness. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
7. Measure the resistance between the (Y501) 5-volt supply circuit in the Map sensor harness connector with the (Y501) 5-volt supply circuit in the ECM harness connector. Is the resistance less than 10 Ohms?
   Yes --> Go To 8
   No --> Repair or replace the engine harness. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
8. Measure the resistance between the MAP Sensor Signal (K68) circuit and the Battery negative terminal. Is the resistance above 100k ohms?
   Yes --> Go To 9
   No --> Repair the MAP Sensor (K68) Signal circuit for a short to ground. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
9. Measure the resistance between the (Y501) 5-volt supply circuit in the sensor harness connector and battery negative. Is the resistance above 100k ohms?
   Yes --> Go To 10
   No --> Test Complete.
10. While monitoring the DRBIII®, jumper the (Y501) 5-volt supply circuit to the (K68) signal circuit in the map sensor harness connector. Did the P0238-MAP SENSOR VOLTAGE TOO HIGH, DTC set?
    Yes --> Test Complete.
    No --> Replace and program the ECM in accordance with the Service Information. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).