C1235 Mercury Code - Right Rear Wheel Speed Sensor Input Signal Missing
Quick Answer
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. Common causes include Mismatched Tire Size, Damage Wheel Speed Sensor Ring, Faulty Right Rear Wheel Speed Sensor. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- C1235 Mercury indicates Right Rear Wheel Speed Sensor Input Signal Missing.
- Common causes
- Common causes include Mismatched Tire Size, Damage Wheel Speed Sensor Ring, Faulty Right Rear Wheel Speed Sensor.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code C1235 Mercury Description
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.
What are the Possible Causes of the DTC C1235 Mercury?
- Mismatched Tire Size
- Damage Wheel Speed Sensor Ring
- Faulty Right Rear Wheel Speed Sensor
- Right Rear Wheel Speed Sensor harness is open or shorted
- Right Rear Wheel Speed Sensor circuit poor electrical connection
- Faulty Anti-Lock Brake System (ABS) Module
How to Fix the DTC C1235 Mercury?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
Code Tech Notes
2002-2004 Mercury Mountaineer Factory Service Bulletin OBDII Code C1235
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the C1235 Mercury code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about C1235 Mercury Code
1. What does the OBDII code C1235 mean for a Mercury vehicle?
C1235 indicates that the right rear wheel speed sensor is not sending a proper signal to the ABS module, which may affect the vehicle's braking system performance.
2. What are the common symptoms of the C1235 code?
Symptoms include the ABS warning light illuminating, loss of ABS functionality, reduced traction control performance, and possible erratic speedometer readings.
3. What causes the C1235 code to appear?
The most common causes are a faulty right rear wheel speed sensor, damaged wiring or connectors, a dirty or corroded tone ring, or a malfunctioning ABS module.
4. Can I drive my Mercury with the C1235 code?
While the vehicle is still drivable, the ABS and traction control systems may not function properly, which could increase the risk of skidding or loss of control in slippery conditions.
5. How do you diagnose the C1235 code?
Diagnosis involves scanning for stored ABS codes, inspecting the right rear wheel speed sensor and its wiring for damage, and testing the sensor's output with a multimeter or oscilloscope.
6. How can I fix the C1235 code on my Mercury?
Repairs may include replacing the right rear wheel speed sensor, repairing or replacing damaged wiring, cleaning or replacing the tone ring, or addressing issues in the ABS module if necessary.
7. How much does it cost to repair a C1235 code?
The cost for repairs can vary, but replacing a wheel speed sensor typically costs $100-$300, including parts and labor. Additional wiring or ABS module repairs may increase the cost.
8. Can a dirty tone ring cause the C1235 code?
Yes, dirt, debris, or corrosion on the tone ring can interfere with the sensor's ability to read wheel speed, leading to the C1235 code.
9. How can I prevent the C1235 code from recurring?
Regularly inspect and clean the wheel speed sensors and tone rings, ensure wiring is secure and undamaged, and address ABS warning lights promptly.
10. Will clearing the code fix the issue?
Clearing the code without addressing the root cause will not fix the issue, and the code will likely return once the vehicle is driven.
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