C0090 & C0095: Right Rear ABS Solenoid #1&#2 Circuit Malfunction

DTC codes C0090 and C0095 are diagnostic trouble codes that are stored in the ABS system of a vehicle when there is a problem with the right rear ABS solenoid circuit. These codes are also known as ABS solenoid circuit malfunction codes or right rear wheel speed sensor circuit codes.

• C0090 - Right Rear ABS Solenoid #1 Circuit Malfunction
• C0095 - Right Rear ABS Solenoid #2 Circuit Malfunction

These codes mean that the ABS system has detected an electrical or mechanical fault in the circuit that controls the ABS solenoid for the right rear wheel. The ABS solenoid is a device that regulates the brake fluid pressure to the wheel and prevents it from locking up during hard braking. The circuit consists of wires, connectors, and the solenoid itself. If there is a short circuit, an open circuit, a poor connection, or a damaged solenoid, the ABS system will not be able to modulate the brake fluid pressure properly and the ABS function will be compromised.

What are the potential causes of these codes?

The potential causes of these codes include:

• Faulty wiring or connectors
• Corrosion or contamination
• Short circuit or open circuit
• Mechanical damage or wear
• Internal leakage or blockage

What are ABS solenoids?

ABS solenoids are electro-hydraulic valves that are located in the ABS hydraulic control unit (HCU) or the ABS modulator. They are controlled by the ABS electronic control unit (ECU) or the ABS module. They have two functions: isolation and dump. The isolation function prevents the brake fluid pressure from increasing when the ABS is activated. The dump function releases the brake fluid pressure when the wheel speed sensor detects that the wheel is about to lock up. By alternating between these two functions, the ABS solenoids modulate the brake fluid pressure to each wheel and maintain the optimal braking performance and stability.

How do ABS solenoids work?

ABS solenoids work by using electrical signals from the ABS ECU or module to open or close the valves that regulate the brake fluid pressure. When the ABS is not activated, the solenoids are normally closed and the brake fluid pressure is determined by the brake pedal input. When the ABS is activated, the solenoids are either opened or closed depending on the wheel speed sensor input. When the solenoid is opened, the brake fluid pressure is isolated and prevented from increasing. When the solenoid is closed, the brake fluid pressure is dumped and released. By doing this, the ABS solenoids prevent the wheels from locking up and skidding.

What are the different types of ABS solenoids?

There are two main types of ABS solenoids: normally closed and normally open. Normally closed solenoids are closed when there is no current and open when there is current. Normally open solenoids are open when there is no current and closed when there is current. The type of solenoid depends on the design and configuration of the ABS system. Some ABS systems use both types of solenoids, while others use only one type.

What are the common problems with ABS solenoids?

ABS solenoids can fail or malfunction due to various reasons such as:

• Faulty wiring or connectors
• Corrosion or contamination
• Short circuit or open circuit
• Mechanical damage or wear
• Internal leakage or blockage

When the ABS solenoids fail or malfunction, they can cause various problems such as:

• ABS warning light on
• ABS not working properly or not working at all
• Reduced braking performance or stability
• Increased stopping distance or skidding
• Unusual noises or vibrations

How to test ABS solenoids?

To test ABS solenoids, you will need some tools and equipment such as:

1. A scan tool
2. A multimeter
3. A test light
4. A jumper wire
5. A repair manual

The steps to test ABS solenoids are as follows:

• Check the ABS warning light. If the ABS warning light is on, scan the ABS system for codes. If you find codes C0090 and C0095, it means that there is a problem with the right rear ABS solenoid circuit.
• Perform a visual inspection of the ABS system. Look for any signs of damage, corrosion, or loose connections on the wiring, connectors, or solenoids. Repair or replace any faulty parts as needed.
• Test the ABS solenoids. Disconnect the electrical connectors from the solenoids and measure the resistance of each solenoid with a multimeter. Compare the readings with the specifications in the repair manual. If the readings are out of range, replace the solenoid. If the readings are within range, proceed to the next step.
• Test the ABS solenoid circuit. Connect a test light or a jumper wire between the positive terminal of the battery and the solenoid connector. Connect a multimeter between the negative terminal of the battery and the solenoid connector. Turn on the ignition and observe the test light or the multimeter. If the test light does not light up or the multimeter does not show any voltage, there is an open circuit in the wiring or the connector. Repair or replace the wiring or the connector as needed. If the test light lights up or the multimeter shows voltage, there is a short circuit in the wiring or the connector. Repair or replace the wiring or the connector as needed.

How to replace ABS solenoids?

To replace ABS solenoids, you will need some tools and equipment such as:

• A wrench or a socket set
• A screwdriver
• A brake bleeder kit
• A new ABS solenoid
• A repair manual

The steps to replace ABS solenoids are as follows:

• Bleed the ABS system. Follow the instructions in the repair manual to bleed the brake fluid from the ABS system. Use a brake bleeder kit to collect the brake fluid and prevent air from entering the system.
• Remove the old ABS solenoid. Locate the ABS solenoid that you want to replace and disconnect the electrical connector from it. Remove the mounting bolts or screws that secure the solenoid to the HCU or the modulator. Pull out the solenoid from the HCU or the modulator and discard it.
• Install the new ABS solenoid. Insert the new solenoid into the HCU or the modulator and align it with the mounting holes. Secure the solenoid with the mounting bolts or screws and tighten them to the specified torque. Connect the electrical connector to the solenoid and make sure it is firmly attached.
• Bleed the ABS system again. Follow the instructions in the repair manual to bleed the brake fluid from the ABS system again. Use a brake bleeder kit to collect the brake fluid and prevent air from entering the system.
• Test the ABS system. Start the engine and check the ABS warning light. If the ABS warning light is off, the ABS system is working properly. If the ABS warning light is still on, scan the ABS system for codes and troubleshoot the problem.

Conclusion

DTC codes C0090 and C0095 are related to the right rear ABS solenoid circuit malfunctions. These codes indicate that there is a problem with the electrical or mechanical operation of the ABS solenoid that controls the brake fluid pressure to the right rear wheel. The symptoms of these codes include ABS warning light on, ABS not working properly or not working at all, reduced braking performance or stability, increased stopping distance or skidding, unusual noises or vibrations. The potential causes of these codes include faulty wiring or connectors, corrosion or contamination, short circuit or open circuit, mechanical damage or wear, internal leakage or blockage. To diagnose and repair these codes, you need to check the ABS warning light, scan the ABS system for codes, perform a visual inspection of the ABS system, test the ABS solenoids, test the ABS solenoid circuit, and replace the faulty ABS solenoid. You also need to bleed the ABS system before and after replacing the ABS solenoid. To prevent ABS solenoid problems, you should maintain the ABS system regularly, use the correct brake fluid, and avoid driving on rough or wet roads. If you are not confident or experienced in diagnosing and repairing ABS solenoid problems, you should see a mechanic for professional help.

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