C0121

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Part 2 Of 2:

CIRCUIT DESCRIPTION
The solenoid valve relay supplies power to the solenoid valve coils in the Electronic Brake (and Traction) Control Module (EBCM/EBTCM). The solenoid valve relay, located in the EBCM/EBTCM, is activated whenever the ignition switch is in the RUN position and no faults are present. The solenoid valve relay remains engaged until the ignition is turned OFF or a failure is detected.

CONDITIONS FOR SETTING THE DTC
^ Diagnostic Trouble Code (DTC) C0121 will set anytime the solenoid valve relay is commanded on and the Electronic Brake (and Traction) Control Module (EBCM/EBTCM) does not see battery voltage at the solenoid valves.
^ DTC C0121 will set anytime the EBCM/EBTCM commands the solenoid valve relay off and battery voltage is still present at the solenoid valves.

ACTION TAKEN WHEN THE DTC SETS
^ A malfunction Diagnostic Trouble Code (DTC) stores.
^ The Antilock Brake System/Traction Control System (ABS/TCS) disables.
^ The amber ABS/TCS indicator(s) turn on.
^ The Red BRAKE Warning indicator turns on.

CONDITIONS FOR CLEARING THE DTC
^ The condition responsible for setting the Diagnostic Trouble Code (DTC) no longer exists and the Scan tool Clear DTCs function is used.
^ 100 ignition cycles pass with no DTCs detected.

DIAGNOSTIC AIDS
^ It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
^ Thoroughly inspect any circuitry that may be causing the complaint for the following conditions:
- Backed out terminals
- Improper mating
- Broken locks
- Improperly formed or damaged terminals
- Poor terminal-to-wiring connections
- Physical damage to the wiring harness

^ The following conditions may cause an intermittent malfunction:
- A poor connection
- Rubbed-through wire insulation
- A broken wire inside the insulation

^ If an intermittent malfunction exists refer to Troubleshooting Procedures Cell 4 in Diagnostic Aids for further diagnosis.
^ The solenoid valve relay is an integral part of the Electronic Brake (and Traction) Control Module (EBCM/EBTCM) and is not serviced separately.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
6. This step checks for a short to ground in CKT 440.
13. This step checks for an open in CKT 440.