Diagnostic Test

WARNING: This page is about a different car, the 2025 Jeep Grand Cherokee. 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 DTC TO RETURN
WARNING:
On vehicles equipped with the high voltage system, you must thoroughly read and follow all High Voltage Safety procedures. In addition, before performing any diagnostic or service procedure near a high voltage component, you must perform the High Voltage Power Down. Failure to follow these instructions may result in possible serious or fatal injury.

Read the HIGH-VOLTAGE SAFETY PROCEDURES. Refer to HIGH VOLTAGE SAFETY PROCEDURES .

When the HIGH-VOLTAGE POWER-DOWN PROCEDURE is necessary. Refer to HIGH VOLTAGE POWER DOWN .
1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
  NOTE:
  Verify that there are no High Temp Cooling Loop leaks or restrictions in the loop. Repair as necessary and retest.
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 Next Step
  No
  - Perform the appropriate INTERMITTENT CONDITION diagnostic procedure. Refer to TESTING FOR AN INTERMITTENT CONDITION .
CHECK THE (ECH) / HIGH VOLTAGE COOLANT HEATER STATUS
1. With the scan tool under the HCP Data tab, check the ECH / High Voltage Coolant Heater Status.
  Perform the following for the status found under the ECH / High Voltage Coolant Heater Status?
  
  OFF
  - Normal Operation
  - Perform the appropriate INTERMITTENT CONDITION diagnostic procedure. Refer to TESTING FOR AN INTERMITTENT CONDITION .
  Locked Until Next Start
  - The heater has detected an out-of-range low voltage, out to range high voltage, loss of communication, or internal concern. Perform the related service diagnostics.
  - The heater will re-attempt operation after a power-cycle
  - Perform the Hybrid Control Processor (HCP) VERIFICATION TEST. Refer to HYBRID CONTROL PROCESSOR (HCP) VERIFICATION TEST .
  Locked Until Next Service
  - The ECH has detected heating coolant difference for inlet and outlet temperatures. Visually inspect for coolant leaks, and air in the system.
  - Perform an ECH unlock under the HCP Misc Functions Tab. Select the Cabin Overheat Lock Reset and then follow the diagnostic scan tool prompts.
  - Perform the Hybrid Control Processor (HCP) VERIFICATION TEST. Refer to HYBRID CONTROL PROCESSOR (HCP) VERIFICATION TEST .
  Locked Permanent
  - The High Voltage (HV) Coolant Heater cannot be recovered or reset
  - Replace the High Voltage (HV) Coolant Heater in accordance with the Service Information. Refer to HEATER, COOLANT, REMOVAL AND INSTALLATION .
  - Perform the Hybrid Control Processor (HCP) VERIFICATION TEST. Refer to HYBRID CONTROL PROCESSOR (HCP) VERIFICATION TEST .