P2524: A/C Request B Circuit High

What it means

The A/C request B circuit signal is above the expected limit. The code does not establish how the vehicle responds to the fault.

At a glance

• Usually lights the check-engine light

How it works

The A/C request B circuit carries a designated air-conditioning request signal between vehicle modules. The control module monitors request B and sets P2524 when its signal rises above the expected limit; the code does not establish how the vehicle responds to that signal.

Common causes

Most likely first.

1. Request wire shorted to battery voltage
2. Connector pins corroded - high contact resistance
3. Supply wire pinched against B+ source

Symptoms

• A/C operation may be unavailable or inconsistent
• A/C request B may not be recognized

How to diagnose it

1. Record freeze-frame data and check for related HVAC or module codes to identify when the request B high-signal fault appeared.
2. Compare scan-tool request B status with the available A/C controls while changing those settings.
3. Inspect the request B wire and connectors for damage, corrosion, loose pins, or contact with a battery-voltage source.
4. Using the wiring diagram, check for a short to battery voltage and test request B wire continuity with the circuit isolated as specified by the manufacturer.
5. If the wiring passes, check the HVAC module output and receiving-module input using the manufacturer's diagnostic procedure.

Common fixes

• Repair request B wiring pinched against a battery-voltage source.
• Clean or repair corroded or loose request B connector terminals.
• Repair or replace damaged request B circuit wiring.
• Repair a faulty HVAC control or module only after circuit tests identify it.

Can I keep driving?

You can generally drive if the vehicle otherwise operates normally, but A/C may be unavailable or inconsistent and request B may not be recognized. The code alone does not indicate an engine or brake fault.