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Code 12 - Loss Of Hydraulic Fluid For One Second Or More During Anti-Lock Stop

NOTE: This test should not be attempted until after base brake system operation has been properly verified. Red BRAKE light should not be on.
  1. Turn ignition off. Release parking brake. Disconnect diagnostic connector (Black/Orange wire) from its mating half (Red wire). Reconnect diagnostic connector. Turn ignition on. Observe Red and Yellow lights after 2 second self-check. If Red and Yellow lights are off, leave ignition on and go to next step.
  2. If Red light is off, Yellow light is on, and Code 12 is falsely set, problem may be caused by brakes having been serviced recently or brake fluid having been added to system recently. If vehicle was not recently serviced, go to INTERMITTENT DIAGNOSIS  . If Yellow RABS light is on and Code 12 is still present (not a false code), check for open circuit on terminal No. 2 (Tan/Light Green wire).
  3. Turn ignition off. Check brake fluid in master cylinder reservoir. If fluid level is okay, go to next step. If fluid level is low, check for leaks in brake system and repair as necessary. Fill master cylinder reservoir to required level and go to step 10).
  4. Remove master cylinder filler cap. Attempt to push down float. Allow float back up. If float goes down and floats back up, go to next step. If float goes down and does not float back up, replace master cylinder reservoir. Bleed brake system and go to step 10).
  5. Disconnect ignition switch harness connector. Disengage parking brake. Check for short to ground on Dark Green/Yellow wire at brake fluid level switch harness connector. If circuit is shorted to ground, repair Dark Green/Yellow wire and go to step 10). If circuit is okay, go to next step.
  6. Engage parking brake and check for a short to ground on Dark Green/Yellow wire at brake fluid level switch harness connector. If wire is shorted to ground, replace resistor/diode element. Reconnect all components and go to step 10). If circuit is okay, go to next step.
  7. Disconnect battery ground cable, fluid level switch, ignition switch, and control module. Check for short to ground on terminal No. 2 (Tan/Light Green wire) of control module harness connector. If circuit is shorted to ground, repair Tan/Light Green wire. Reconnect all components and go to step 10). If circuit is okay, go to next step.
  8. Reconnect ignition switch. Check for short to ground on terminal No. 2 (Tan/Light Green wire) of control module harness connector. If circuit is shorted to ground, replace ignition switch. Reconnect all components and go to step 10). If circuits are okay, go to next step.
  9. Reconnect brake fluid level switch. Check for short to ground on terminal No. 2 (Tan/Light Green wire) of control module harness connector. If circuit is shorted to ground, replace brake fluid level switch. Reconnect all components and go to step 10). If circuits are okay, replace control module and go to next step.
  10. Ensure ignition is off. Reconnect negative battery cable. Ensure all connectors are connected and secure. Retrieve trouble codes. See RETRIEVING TROUBLE CODES  . If Code 12 is present and all steps are complete, go to INTERMITTENT DIAGNOSIS  . If all steps are not complete, return to last step completed and continue. If Code 16 is present, go to CODE 16 under TEST DRIVE  . If any other trouble code is present, go to corresponding test for appropriate trouble code.
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