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C1236 Mercury Code - Left Rear Wheel Speed Sensor Input Signal Missing

- Code Popularity: 7,506 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
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What are the Possible Causes of the DTC C1236 Mercury?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Mismatched Tire Size
  • Damage Wheel Speed Sensor Ring
  • Faulty Left Rear Wheel Speed Sensor
  • Left Rear Wheel Speed Sensor harness is open or shorted
  • Left Rear Wheel Speed Sensor circuit poor electrical connection
  • Faulty Anti-Lock Brake System (ABS) Module
⚠ Does your Mercury have Safety Recalls? → Check here

How to Fix the DTC C1236 Mercury?

Review the 'Possible Causes' mentioned above and visually examine the corresponding wiring harness and connectors. Ensure to check for any damaged components and inspect the connector pins for signs of being broken, bent, pushed out, or corroded.

Code Tech Notes

There is a Factory Service Bulletin for the 2002-2004 Mercury Mountaineer:
2002-2004 Mercury Mountaineer Factory Service Bulletin OBDII Code C1236

Search for C1236 Mercury Questions and Answers: Search here →

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the C1236 Mercury code, it typically requires 1.0 hour of labor. The specific diagnosis time and labor rates at auto repair shops can differ based on factors such as the location, make and model of the vehicle, and even the engine type. It is common for most auto repair shops to charge between $75 and $150 per hour.

What are Code Possible Symptoms?

  • Anti-Lock Brake System (ABS) Warning Light ON
  • Engine Light ON (or Service Engine Soon Warning Light)

Code C1236 Mercury Description

The Anti-Lock Brake System (ABS) Module receives wheel speed readings from each wheel speed sensor and processes this information to determine if an ABS event is necessary. The wheel speed sensor detects the magnetic field of the sensor ring as it passes the face of the active wheel speed sensor.
The active wheel speed sensor generates a signal that is sent to the ABS module. The wheel speed sensor circuitry connects to the ABS module through 2 wires and a connector at each wheel speed sensor. When the ignition is turned to the RUN position, the ABS module carries out a self-test by sending a reference voltage to all of the wheel speed sensors through their circuitry to determine if they are functional.
The ABS module continuously monitors and compares the rotational speed of each wheel and when it detects an impending wheel lock, modulates the brake pressure to the appropriate brake caliper. This is accomplished by triggering the hydraulic control unit (HCU) to open and close the appropriate solenoid valves. Once the affected wheel returns to normal speed, the ABS module returns the solenoid valves to their normal position and normal (base) braking resumes.

OBDII Code C1236 Mercury - Left Rear Wheel Speed Sensor Input Signal Missing - AutoCodes.com
C1236 Mercury Code - Left Rear Wheel Speed Sensor Input Signal Missing

Need More Information on the Code?

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