Diagnostic Test

WARNING: This page is about a different car, the 2024 Jeep Grand Wagoneer L and 2024 Jeep Grand Wagoneer. However, it is still accessible from the selected car via links, so may be relevant.

READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR THE DTC TO RETURN
1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
2. For future reference, with the scan tool, run and save a vehicle Scan Report and all related recorded data.
3. With the scan tool, erase all DTCs.
4. Turn the ignition off for a minimum of 10.0 seconds.
5. Turn the ignition on.
6. Using the When Monitored and Set Conditions above and recorded data, operate the vehicle in the conditions that set the DTC.
7. With the scan tool, read DTCs.
  Did the DTC return?
  
  Yes
  - Go To 2
  No
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
CHECK FOR OTHER DTCS
1. Refer to the recorded DTCs.
  Are there any other O2 Sensor Heater circuit DTCs active or pending?
  
  Yes
  - Perform the applicable diagnostic procedure(s). Refer to DIAGNOSTIC CODE INDEX .
  No
  - Go To 3

CHECK THE O2 SENSOR 2/1 HEATER ELEMENT RESISTANCE

Turn the ignition off.
NOTE:
Allow the O2 Sensor heater a few minutes to cool down from the heater test performed with the scan tool.
Disconnect the O2 Sensor 2/1 harness connector.

Measure the resistance of the O2 Sensor 2/1 Heater Element across the O2 Sensor, between the O2 Heater Control terminal and the Heater ground terminal (component side).

NOTE:

If possible, it's best to measure the O2 Sensor 2/1 Heater Element resistance value at approximately 20°C (68°F). The resistance value will vary with different temperature values. If the O2 Sensor is obviously warmer or cooler than the recommended temperature, use the table below to estimate what the resistance range should be. The MAXIMUM allowable resistance would be 12.5 Ohms at 1000°C.

Celsius	Fahrenheit	Resistance Range
0°C	32°F	3.1 - 4.2 Ohms
20°C	68°F	3.3 - 4.4 Ohms
100°C	212°F	3.85 - 5.1 Ohms

Is the O2 Sensor resistance within the acceptable range?

Yes

Go To 4

Verify that there is good pin to terminal contact in the Sensor and Control Module connectors. If no problems are found, replace the O2 Sensor in accordance with the Service Information. Refer to OXYGEN SENSOR(S) .
Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

CHECK THE (F344) ASD RELAY OUTPUT CIRCUIT FOR AN OPEN OR HIGH RESISTANCE
1. Turn the ignition on.
2. Measure the voltage on the (F344) ASD Relay Output circuit at the O2 Sensor 2/1 harness connector.
  Is the voltage equal to Battery voltage?
  
  Yes
  - Go To 5
  No
  - Repair the (F344) ASD Relay Output circuit for an open circuit. If the fuse for the (F344) ASD Relay Output circuit in the Power Distribution Center is open, repair the circuit for a short to ground.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK FOR HIGH RESISTANCE IN THE O2 SENSOR 2/1 (K199) HEATER CONTROL CIRCUIT
1. Disconnect the PCM C2 harness connector.
2. Measure the resistance of the O2 Sensor 2/1 (K199) Heater Control circuit between the Oxygen Sensor 2/1 harness connector and the PCM C2 harness connector.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Go To 6
  No
  - Repair the O2 Sensor 2/1 (K199) Heater Control circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK RELATED PCM AND COMPONENT CONNECTIONS
1. Perform any Service Bulletins that apply.
2. Disconnect all PCM harness connectors.
3. Disconnect all related in-line harness connections (if equipped).
4. Disconnect the related component harness connectors.
5. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
  - Proper connector installation.
  - Damaged connector locks.
  - Corrosion.
  - Other signs of water intrusion.
  - Weather seal damage (if equipped).
  - Bent terminals.
  - Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
  - Terminals that have been pushed back into the connector cavity.
  - Check for spread terminals and verify proper terminal tension.
  Repair any conditions that are found.
6. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
9. With the scan tool, erase DTCs.
10. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
11. With the scan tool, read DTCs.
  Did the DTC return?
  
  Yes
  - Replace and program the Powertrain Control Module (PCM) in accordance with the Service information. Refer to MODULE, POWERTRAIN CONTROL (PCM), REMOVAL AND INSTALLATION .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  - Test complete.