2021 Jeep Wrangler PCM Enhancements TSB 18-022-24 REV. A

Symptoms

Owners of affected 2021 Jeep Wrangler vehicles may experience a Malfunction Indicator Lamp (MIL) illumination. This often accompanies specific diagnostic trouble codes (DTCs). Additionally, customers might notice issues with oil life degradation when the fuel and oil refresh mode is active.

Some vehicles may also be unable to enter electric mode driving while the Fuel Oil Refresh Mode (FORM) is active, or experience FORM staying on for an extended period. Other software enhancements included in this update relate to On Board Fuel Consumption Monitoring (for China Only markets).

Fault Codes / DTCs

If your 2021 Jeep Wrangler is experiencing these symptoms, a scan tool may reveal one or more of the following Diagnostic Trouble Codes:

Code	Description
U0402-00	Implausible Data Received From TCM
U145D	Implausible Data Received From TCM On D-PT

Diagnosis / Trigger Conditions

To diagnose the issue, a technician will use a scan tool, such as wiTECH, along with the diagnostic procedures available in DealerCONNECT/Service Library. They will verify that all related systems are functioning as designed. If other DTCs or symptom conditions are present beyond those listed in this bulletin, they must be addressed first before proceeding with the TSB repair.

Repair Procedure Summary

This TSB, 18-022-24 REV. A, involves reprogramming the Powertrain Control Module (PCM) with the latest available software. For this update to be effective, several additional modules must also be flashed with their latest software versions. These include the Battery Pack Control Module (BPCM), Transmission Control Module (TCM), Integrated Dual Charging Control Module (IDCM), and the Hybrid Control Processor (HCP) / Auxiliary Hybrid Control Processor (AHCP), also known as the Power Inverter Module (PIM).

During the repair, a battery charger must be connected to maintain a 12-volt system voltage. After the PCM is reprogrammed, all DTCs that may have been set during the process will be cleared using the wiTECH application. Finally, the technician will verify that the IDCM, BPCM, HCP / AHCP, and TCM are also updated to their latest software.

Required Tools or Parts

The primary tool required for this repair is a wiTECH diagnostic system or an equivalent scan tool capable of performing module reprogramming.

Important Warnings

Owners and technicians should be aware of critical warnings related to this procedure:

• WARNING!! "Failure to update the IDCM, BPCM, HCP / AHCP and TCM module following a PCM software update may result in vehicle malfunctions."
• CAUTION!! Before performing any software reprogramming, it is essential to make the vehicle safe. This includes ensuring the power supply of the high-voltage system is disconnected when working with high-voltage components.
• Only specifically trained technicians qualified to perform repairs on vehicles with high-voltage systems are authorized to work on the vehicle.
• Always follow general instructions for working safely on hybrid/electric vehicles and use appropriate general equipment and Personal Protective Equipment (PPE).
• If the flash process is interrupted or aborted, it should be restarted.
• Technicians must also follow the 04B Recall Instructions and utilize the Labor Operation Codes (LOPs) contained within that Recall.

Owner Action

If your 2021 Jeep Wrangler is exhibiting a Malfunction Indicator Lamp (MIL) illumination, displaying DTCs U0402-00 or U145D, or experiencing any of the described symptoms related to oil life degradation or electric mode, you should contact your authorized Jeep dealer. They will perform the necessary software updates under TSB 18-022-24 REV. A. This repair is reimbursable under warranty provisions.

This bulletin supersedes Technical Service Bulletin (TSB) 18-022-24, issued on March 14, 2024. It was also released as Rapid Service Update (RSU) 21-124 on August 26, 2021, which expired 18 months after its issue date.

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Source: NHTSA ID: 11001250