ABS and brakes

C0085 — Left Rear ABS Solenoid #2 Circuit Malfunction

Severity: medium Drive with care, to a shop

What C0085 means

The ABS control module constantly monitors the circuits of the solenoid valves in the hydraulic unit, which hold and release brake pressure at each wheel. C0085 means it found an electrical fault in the left rear solenoid #2 circuit, such as an open, a short, or out-of-range resistance. The module usually disables ABS and traction control, either for that circuit or entirely.

Symptoms

  • ABS warning light is on
  • Traction or stability control light is on or flashing
  • Traction control barely responds on slippery roads
  • Wheels may lock up under hard braking
  • Longer stopping distance on wet or icy surfaces

Possible causes

  1. Damaged or corroded wiring or connector in the left rear solenoid circuit
  2. Failed solenoid coil (valve #2) in the ABS hydraulic unit
  3. Low or unstable power to the ABS module: weak battery, bad ground, blown fuse
  4. Internal fault in the ABS module or hydraulic unit
  5. CAN bus communication fault between the ABS and traction control modules
  6. Software error in the module (uncommon)

How to diagnose

  1. Scan all modules for codes and freeze frame data, noting any power or CAN codes
  2. Test the battery, charging voltage, fuses and the ABS module ground
  3. Inspect the harness and hydraulic unit connector for corrosion, moisture, chafing and damage
  4. Unplug the connector and measure solenoid coil resistance against the factory spec
  5. Check the wiring for opens and shorts to ground or power between the module and connector
  6. Run the scan tool actuator test and listen for the valve to operate
  7. Check for software updates and communication errors on the CAN bus
  8. Clear the code and see whether it returns after a test drive

Common fixes

  • Repair damaged wires and clean or replace the connector
  • Fix power problems: charge or replace the battery, restore the ground
  • Replace the hydraulic unit or its valve body if the coil has failed
  • Replace or repair the ABS control module
  • Update or reflash the module software

Questions and answers

Can I drive with a C0085 code?

Yes, but carefully and not for long. The standard brakes still work, but ABS and traction control are off, so stopping distances increase on slippery roads.

What most often causes C0085?

Most often it's damaged wiring or a corroded connector near the left rear wheel or the hydraulic unit. Power supply problems and a failed solenoid coil come next.

Can I just clear the C0085 code?

You can, but if the fault is real the code and warning light will return. Find the cause first, whether wiring, power or the module itself.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.