What Does P056A Mean?
The ECM has detected a malfunction in the cruise control 'Increase Distance' signal circuit, used on vehicles equipped with adaptive cruise control (ACC). This signal commands the ACC system to increase the following distance to the vehicle ahead. The ECM is not receiving a valid signal when the driver presses the distance increase button, preventing adjustment of the ACC gap setting.
Common Causes
40%
Faulty distance increase button in the steering wheel cruise control switch module with worn or damaged contacts
25%
Open or corroded wiring in the distance increase signal circuit between the steering wheel switch and ACC/ECM module
25%
Clock spring failure affecting the distance increase signal trace while other ACC functions remain operational
10%
ACC control module or ECM input circuit fault preventing recognition of the distance increase command
Diagnostic Steps
1
Step 1: With ACC engaged and following a vehicle, press the distance increase button. The gap indicator on the instrument cluster should increase by one step. If no change occurs, the signal is not reaching the control module.
2
Step 2: Monitor the ACC distance input voltage at the ECM while pressing the increase button. The voltage should change to the expected level for the increase command.
3
Step 3: Disconnect the steering wheel switch assembly and measure resistance at the distance increase contact. Compare to the manufacturer's specified resistance for this function in the resistive-ladder network.
4
Step 4: Test clock spring continuity on the distance increase signal circuit while rotating the steering wheel through its full range.
5
Step 5: If the switch and wiring test good, check the ACC module connector pins for corrosion. Verify the ACC module software is current, as some distance setting issues can be resolved with a module reprogram.
Estimated Repair Cost
$50 - $400
Parts + labor, varies by vehicle and location
The ECM has detected a malfunction in the cruise control 'Increase Distance' signal circuit, used on vehicles equipped with adaptive cruise control (ACC). This signal commands the ACC system to increase the following distance to the vehicle ahead. The ECM is not receiving a valid signal when the dri...
The most common cause of P056A (Cruise Control "Increase Distance" Signal) is: Faulty distance increase button in the steering wheel cruise control switch module with worn or damaged contacts
Typical repair costs for P056A range from $50 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The driver cannot increase the ACC following distance via the button, but the current distance setting remains active. The driver can still use the brake pedal to create additional space. ACC engagement and cancellation remain fully functional.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P056A to identify the root cause.
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Quick Info
Category
Powertrain
System
Adaptive Cruise Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
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