Reference meaning
What does this code mean?
The wording below belongs to the named make and communication. Match the complete code, reporting module, model year and engine before applying it.
A code identifies a detected condition, not a part that must automatically be replaced.
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A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
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Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Scan worksheet →Manufacturer wording
Source wording can vary by vehicle and suffix. It is shown as written, not as a universal diagnosis.
B21DD-84System Voltage-Signal Below Allowable Range
B21DD-85System Voltage-Signal Above Allowable Range
B21DD-84System Voltage-signal Below Allowable Range
Manufacturer communications
11Original wording in English
JEEP
If the Power Liftgate (PLG) does not operate following battery drainage or when DTCs B2199-16 or B21DD-16 are active, perform the following steps: 1. Verify Battery Voltage: Ensure battery voltage is at nominal value (minimum 12.5 V). Charge the battery, if necessary before proceeding. 2. Confirm Low Voltage DTCs: After charging…
RAM
Unable To Start Vehicle - Shifter Inoperable Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● B2199-16 - Battery Voltage-circuit Voltage Below Threshold. ● B21DD-84 - System Voltage-signal Below Allowable Ran…
RAM
Unable To Start Vehicle - Shifter Inoperable Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● B2199-16 - Battery Voltage-circuit Voltage Below Threshold. ● B21DD-84 - System Voltage-signal Below Allowable Ran…
JEEP
Flash: Radio Frequency Hub Module (RFHM) Updates Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician may find one or more of the following Diagnostic Trouble Code (DTCs) have been set: ? B21DD-84 - System Voltage-Signal Below Allowable Range. ? B21DD-85 - System Vol…
Check vehicle applicability
11A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
| Make | Model | Model year |
|---|---|---|
| Jeep | GRAND CHEROKEE ↗ | 2021 |
| Jeep | GRAND CHEROKEE 4XE ↗ | 2022 |
| Jeep | GRAND WAGONEER ↗ | 2026 |
| Jeep | GRAND WAGONEER ↗ | 2025 |
| Jeep | GRAND WAGONEER ↗ | 2024 |
| Jeep | WAGONEER ↗ | 2026 |
| Jeep | WAGONEER ↗ | 2025 |
| Jeep | WAGONEER ↗ | 2024 |
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.