2021 Jeep Wrangler PIM Software Update TSB 08-059-25

Owners of 2021 Jeep Wrangler vehicles equipped with the 2.0L I4 DOHC DI Turbo PHEV Engine (Sales Code ECX) may experience a Jeep Wrangler PIM fault leading to a Malfunction Indicator Lamp (MIL) illumination. This condition is detailed in Technical Service Bulletin (TSB) 08-059-25, issued on March 7, 2025.

This TSB specifically addresses issues related to the Power Inverter Module (PIM) software, which can cause significant operational problems for the hybrid system.

Symptoms

Customers may observe a Malfunction Indicator Lamp (MIL) illuminating on the dashboard. Beyond the MIL, the Jeep Wrangler PIM fault can manifest in several ways:

• The Electric Vehicle (EV) system may shut down unexpectedly when the vehicle attempts to transition to Internal Combustion Engine (ICE) motive power.
• The Engine Stop Start (ESS) function will not operate as intended.

Fault Codes / DTCs

Upon investigation, a technician using a diagnostic scan tool will likely find one or more of the following Diagnostic Trouble Codes (DTCs) stored in the vehicle's system:

Diagnosis / Trigger Conditions

To diagnose this Jeep Wrangler PIM fault, a technician will use a scan tool, such as wiTECH, to verify that all related systems are functioning correctly. The presence of the specific DTCs (P0C19-00 or P1B03-00) or the described symptoms will confirm the need for this bulletin's repair procedure. Any other DTCs or symptom conditions should be addressed before proceeding with the PIM software update.

Important Warnings

Several critical precautions must be observed during the repair process to ensure safety and proper execution:

• CAUTION: Before performing any software reprogramming, it is essential to make the vehicle safe. Technicians must ensure the power supply of the high-voltage system is disconnected throughout any operation involving or implying contact with high voltage components/systems.
• CAUTION: Only specifically trained technicians, qualified to perform repairs on vehicles with high voltage systems under current national laws and regulations, are authorized to work on the vehicle.
• CAUTION: Before performing any diagnostic repair work on a hybrid/electric vehicle, technicians must carefully read and comply with general instructions for working safely and use suitable general equipment and Personal Protective Equipment (PPE).
• NOTE: A battery charger must be installed to ensure sufficient battery voltage is maintained during the flash process.
• NOTE: If the flash process is interrupted or aborted for any reason, it must be restarted from the beginning.
• NOTE: The vehicle must not be connected to a high voltage charger while software updates are being performed.

Repair Procedure Summary

The resolution for this Jeep Wrangler PIM fault involves reprogramming the Auxiliary Hybrid Control Processor (AHCP), also known as the Power Inverter Module (PIM), with the latest available software. The general steps for the repair, as outlined in TSB 08-059-25, are:

1. Disable HV Battery Contactors: Using the wiTECH diagnostic tool, navigate to the Misc Functions tab and select