2021 Jeep Grand Cherokee
Mileage
71,792
Service Date
6/25/2025
Services Performed
- Scanned for codes before inspection: -Engine P00FD
- Battery "B" State of Charge Performance -Transmission P0562-00
- System Voltage Low – – Stored. -Antilock Brakes C212A-16
- System Voltage – Circuit Voltage Below Threshold – Stored. U0403-00
- Implausible Data Received From Transfer Case – – Stored. Most other modules had some sort of low voltage related faults as well. P00FD is a concern with the auxiliary battery. Connected draw monitor tool to the OBD2 connector and disconnected BOTH negative battery cables. Noted the auxiliary battery was hot. After waiting one hour the drain was measured at a variable 66-158mA. Typical maximum allowable is 50mA or less. Traced the excessive drain to an aftermarket GPS/Tracker unit that is tapped into the OBD2 power wire under the dash. Unplugged unit and drain measured at 10-20 mA after full system shut down again. Draw from GPS is excessive, advise leave disconnected or remove all together. Drain increases over 1000mA when the aux battery is connected. Battery has an internal fault like a shorted cell that is also draining the main battery, which is reason for hot battery and the P00FD code. Also note the main (new) battery is incorrect. Vehicle charging and BMS system is designed for AGM batteries. The main battery is a standard lead acid MTP-48/H6, and the aux is the correct AGM-14. Mixing battery architecture can cause drain and charging issues. Need to replace aux battery AND advise to change main battery to the correct type, MTX-48/H6 then reset the BMS for new batteries.
- Replace main and aux batteries under the passenger seat.
Ricardo S. gave our service a 5 star review on 6/26/2025
