C1236 Mercury Code - Left 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 Left 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
- C1236 Mercury indicates Left Rear Wheel Speed Sensor Input Signal Missing.
- Common causes
- Common causes include Mismatched Tire Size, Damage Wheel Speed Sensor Ring, Faulty Left 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 C1236 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 C1236 Mercury?
- 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
How to Fix the DTC C1236 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 C1236
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. 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 C1236 Mercury Code
1. What does the OBDII code C1236 mean for a Mercury vehicle?
C1236 indicates that the left rear wheel speed sensor is not sending a signal to the ABS module, which affects the vehicle's anti-lock braking system.
2. What are the common symptoms of the C1236 code in a Mercury?
Common symptoms include the ABS warning light being illuminated, reduced ABS functionality, or the vehicle's traction control system not working properly.
3. What causes the C1236 code to appear?
The most common causes are a faulty left rear wheel speed sensor, damaged wiring or connectors, debris blocking the sensor, or a malfunctioning ABS module.
4. Can I drive my Mercury with the C1236 code?
While the vehicle may still be drivable, the ABS and traction control systems will likely be compromised, increasing the risk of wheel lockup during hard braking.
5. How do I diagnose the C1236 code in my Mercury?
Start by inspecting the left rear wheel speed sensor, its wiring, and related connectors for damage or debris. Use a scan tool to monitor live data from the sensor to confirm if it’s sending a signal.
6. How can I fix the C1236 code on a Mercury?
Repair or replace the left rear wheel speed sensor if it’s faulty, clean any debris near the sensor, and repair any damaged wiring or connectors. If the issue persists, the ABS module may need attention.
7. How much does it cost to repair a C1236 code on a Mercury?
Replacing a wheel speed sensor typically costs between $100 and $300, including parts and labor. Wiring repairs or ABS module replacement can be more expensive.
8. Can a dirty wheel hub cause the C1236 code?
Yes, dirt, debris, or rust around the wheel hub can interfere with the speed sensor's ability to detect the wheel's rotation, triggering the code.
9. Will resetting the code fix the problem permanently?
No, clearing the code without addressing the underlying issue will only temporarily remove the warning. The code will return if the problem persists.
10. Can a bad ABS module cause the C1236 code?
Yes, while less common, a malfunctioning ABS module can fail to process the wheel speed sensor's signal, leading to this code.
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