Torque Management Feedback Signal B High
The P2643 code means the vehicle's onboard diagnostic system has detected: Torque Management Feedback Signal B High. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $100 - $800 (parts and labor)
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Common Symptoms
- Torque B signal reads higher than expected
- Redundancy check failure between A and B
- Possible harsh shifting
- Check engine light on
Probable Causes (Ranked by Likelihood)
- Short to voltage in torque B circuit Very High
- ECM B output driver stuck high High
- Electromagnetic interference on CAN bus Moderate
- Software mismatch after module replacement Low
Step-by-Step Diagnostic Procedure
-
Compare B signal to A signal for discrepancy
-
Check B circuit wiring for voltage shorts
-
Verify CAN bus shielding integrity
-
Confirm ECM and TCM software match after any replacements
Frequently Asked Questions
Why would signal B be high when signal A is normal?
They may use different circuit paths or calculation methods. A wiring fault or ECM output driver issue can affect one without the other.
Do I need a factory scan tool for P2643?
A factory or advanced aftermarket scan tool is recommended to view both torque signal values simultaneously for comparison.
Can module replacement cause P2643?
Yes. If an ECM or TCM is replaced without proper programming, the torque management calibrations may not match, causing signal discrepancies.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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