Pinpoint Test B: U0121:00
- Refer to MODULE COMMUNICATION NETWORK
for schematic and connector information.
Normal Operation and Fault Conditions
Refer to: Controller Area Network (CAN) Module Communications Network - System Operation and Component Description .
DTC Fault Trigger Conditions
DTC Description Fault Trigger Condition SIMA U0121:00 Lost Communication With Anti-Lock Brake System (ABS) Control Module 'A': No Sub Type Information A continuous monitoring DTC that sets in the SIMA if the ABS module did not respond to SIMA requests. Possible Sources
- FD-CAN concern
- Battery voltage concern
- ABS module
- B1 CHECK THE COMMUNICATION NETWORK
- Connect the diagnostic tool.
- Ignition ON.
- Using a diagnostic scan tool, perform a network test.
Does the ABS module pass the network test?
Yes GO to B2 No Refer to: Controller Area Network (CAN) Module Communications Network . - B2 RECHECK THE SIMA (SWITCH INPUT MODULE A) DIAGNOSTIC TROUBLE CODES (DTCS)
- Using a diagnostic scan tool, clear the DTCs.
- Wait 10 seconds.
- Using a diagnostic scan tool, check for SIMA DTCs.
Is DTC U0121:00 retrieved again?
Yes GO to B3 No The system is operating correctly at this time. The DTC may have been set due to high network traffic or an intermittent voltage condition. - B3 RETRIEVE THE ABS (ANTI-LOCK BRAKE SYSTEM) MODULE DTCS
- Using a diagnostic scan tool, perform the ABS module self-test.
Are any ABS module DTCs present?
Yes Refer to: Anti-Lock Brake System (ABS) and Stability Control . No GO to B4 - B4 CHECK FOR DTC (DIAGNOSTIC TROUBLE CODE) U0121:00 OR U0121:87 SET IN OTHER MODULES
- Using a diagnostic scan tool, clear the DTCs.
- Ignition OFF.
- Wait 10 seconds.
- Ignition ON.
- Using a diagnostic scan tool, retrieve all DTCs.
Is DTC U0121:00 or U0121:87 set in other modules?
Yes GO to B5 No GO to B6 - B5 CHECK FOR CORRECT ABS (ANTI-LOCK BRAKE SYSTEM) MODULE OPERATION
- Ignition OFF.
- Disconnect and inspect the ABS module connector.
- Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary
- Reconnect the ABS module connector. Make sure it seats and latches correctly.
- Operate the system and determine if the concern is still present.
Is the concern still present?
Yes CHECK OASIS for any applicable service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new ABS module. Refer to: Anti-Lock Brake System (ABS) Module - Vehicles With: Vacuum Brake Booster . No The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues. - B6 CHECK FOR CORRECT SIMA (SWITCH INPUT MODULE A) OPERATION
- Disconnect and inspect all SIMA connectors.
- Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary
- Reconnect all SIMA connectors. Make sure they seat and latch correctly.
- Operate the system and determine if the concern is still present.
Is the concern still present?
Yes CHECK OASIS for any applicable service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new SIMA. Refer to: Switch Input Module A (SIMA) . No The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.