P2550: Torque Management Request Input Signal B Low

What it means

Torque management request input signal B is below the expected limit. The code does not identify the cause or control response.

At a glance

• Usually lights the check-engine light

How it works

Torque management request input signal B carries a request for the powertrain control module to reduce or adjust engine torque. P2550 sets when signal B is below the expected limit, which can result from a short to ground, damaged wiring, a poor connector, or a fault in the module sending the request.

Common causes

Most likely first.

1. Signal wire shorted to ground
2. Open or damaged wiring
3. Loose or corroded connector
4. Fault in the module sending the request

Symptoms

• Check-engine light
• Reduced or inconsistent engine power
• Altered transmission shifting

How to diagnose it

1. Record freeze-frame data and check live torque request signal B to confirm whether it stays low or changes with operating conditions.
2. Scan for related codes in the powertrain and requesting modules that may identify a shared wiring or sender problem.
3. Inspect signal B wiring and connectors for chafing, an open, corrosion, or loose terminals.
4. Use the wiring diagram to test signal B for a short to ground and check circuit continuity against the manufacturer's specification.
5. If the circuit passes, test the request switch or sensor and verify the sending module's reported output.

Common fixes

• Repair signal B wiring shorted to ground or damaged by chafing.
• Clean and secure a loose or corroded signal B connector.
• Replace a faulty request switch or sensor if its output is below specification.
• Address the sending module fault only after its power, grounds, and signal path are verified.

Can I keep driving?

Drive cautiously only if engine power and shifting remain predictable; avoid towing and hard acceleration while signal B is reading low. Stop if power becomes inconsistent or shifts interfere with safe control.