P242C

P242C-EXHAUST GAS TEMPERATURE SENSOR CIRCUIT LOW- BANK 1 SENSOR 3





For a complete wiring diagram Refer to Diagrams/Electrical.

Theory of Operation


The Exhaust Temperature Sensors are used by the electronic control module (ECM) to monitor the engine exhaust temperatures in the aftertreatment system. The Exhaust Temperature Sensors are thermistors and change resistance based on the temperature being measured. The ECM provides a 5-volt reference voltage to the sensor. The ECM monitors the change in signal voltage and converts this to a temperature value. When the exhaust gas temperature is cold, the sensor or thermistor resistance is high. The ECM signal voltage only pulls down a small amount through the sensor to ground. Therefore, the ECM senses a high signal voltage or low temperature. When the exhaust gas temperature is hot, the sensor resistance is low. The signal voltage pulls down a large amount. Therefore, the ECM senses a low signal voltage, or a high temperature. The ECM will set the fault code if it detects that the Exhaust Temperature Sensor 1/1 Signal voltage is less than a calibrated voltage for longer than a calibrated period. The ECM illuminates the MIL lamp immediately when the diagnostic runs and fails. A default value for the Exhaust Temperature Sensor 1/1 reading will be used and active regeneration of the diesel particulate filter will be disabled. The ECM will turn off the MIL lamp immediately after the diagnostic runs and passes.

- When Monitored:
Ignition ON

- Set Condition:
The ECM will set the fault if it detects that the diesel oxidation catalyst inlet exhaust gas temperature sensor signal voltage is greater than a calibrated voltage for more than a calibrated time.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview


Diagnostic Test


1. TEMPERATURE SENSOR
Disconnect the Exhaust Temperature Sensor 1/3.

NOTE: Check connectors - Clean/repair as necessary.

Using an ohmmeter check the resistance of the sensor.

NOTE: The sensor's resistance value increases with decreasing temperature @ 50° C (122° F) resistance ranges from 82k to 137k ohms.

Is the resistance between 82k and 300k ohms at ambient temperature?

Yes


- Go To 2


No


- Replace the sensor
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



2. (K372) EXHAUST GAS TEMPERATURE 1/3 SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT
Reconnect the Temperature sensor.
Disconnect the ECM harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between the (K372) Exhaust Gas Temperature 1/3 Signal circuit and the (K900) Sensor ground circuit at the ECM harness connector.
Is the resistance between 82k and 300k ohms at ambient temperature?

Yes


- Go To5


No


- Go To 3



3. (K372) EXHAUST GAS TEMPERATURE 1/3 SIGNAL CIRCUIT SHORTED TO GROUND
Disconnect the Exhaust Gas Temperature Sensor 1/3.
Measure the resistance between ground and the (K372) Exhaust Gas Temperature 1/3 Signal circuit.
Is the resistance below 100 Ohms?

Yes


- Repair the short to ground in the (K372) Exhaust Gas Temperature 1/3 Signal circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test


No


- Go To 4



4. (K900) SENSOR GROUND CIRCUIT OPEN
Measure the resistance of the (K900) Sensor ground circuit between the sensor harness connector and the ECM harness connector.
Is the resistance less than 10 Ohms?

Yes


- Go To


No


- Repair the open in the (K900) Sensor ground circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



5. (K372) EXHAUST GAS TEMPERATURE 1/3 SIGNAL CIRCUIT SHORTED TO ANOTHER CIRCUIT
Measure resistance between the (K372) Exhaust Gas Temperature 1/3 Signal circuit and other circuits at the ECM harness connector.
Is the resistance more than 100 k ohms?

Yes


- Go to 6


No


- Repair the circuits that are shorted together.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



6. ECM
Reconnect the ECM harness connector.
While monitoring the Exhaust Gas Temperature Sensor 1/3 with scan tool, use a jumper wire and connect the (K372) Exhaust Gas Temperature 1/3 Signal circuit and the (K900) Sensor ground circuit at the sensor connector.
Did the DTC for voltage high go inactive and the DTC for voltage low become active?

Yes


- Refer to the INTERMITTENT CONDITION - DIESEL Symptom. Intermittent Condition


No


- Replace the ECM.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test