Pinpoint Tests BK: DTC U0121:00

Instrumentation, Message Center and Warning Chimes

Pinpoint Test BK: DTC U0121:00

Normal Operation
- DTC U0121:00 (Lost Communication With Anti-Lock Brake System [ABS] Control Module: No Sub-Type Information) - sets in the Instrument Panel Cluster (IPC) if data messages received from the ABS module over the High Speed Controller Area Network (HS-CAN) are missing. For a complete list of all network messages, refer to Module Communications Network Testing and Inspection.

This pinpoint test is intended to diagnose the following:

- ABS module
- IPC


PINPOINT TEST BK: DTC U0121:00

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BK1 VERIFY THE CUSTOMER CONCERN

- Ignition ON.
- Verify that there is an observable symptom present.
- Is an observable symptom present?

Yes
GO to BK2.

No
The system is operating normally at this time. The DTC may have been set due to high network traffic or an intermittent fault condition.

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BK2 CHECK THE COMMUNICATION NETWORK

- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Network Test .
- Carry out the network test.
- Does the ABS module pass the network test?

Yes
GO to BK3.

No
REFER to Module Communications Network Testing and Inspection.

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BK3 RETRIEVE THE RECORDED DTCs FROM THE IPC SELF-TEST

- Check for recorded DTCs from the IPC self-test.
- Is DTC U3003:16 or DTC U3003:17 recorded?

Yes
GO to Pinpoint Test BX (U3003:16) or GO to Pinpoint Test BY (U3003:17). Pinpoint Tests BX: DTC U3003:16 Pinpoint Tests BY: DTC U3003:17

No
GO to BK4.

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BK4 RECHECK THE IPC DTCs

- Clear the DTCs. Repeat the IPC self-test.
- Is DTC U0121:00 still present?

Yes
INSTALL a new ABS module. REFER to Vehicle Dynamic Systems Service and Repair. CLEAR the DTCs. REPEAT the IPC self-test.

If DTC U0121:00 is still present, INSTALL a new IPC. REFER to Instrument Panel Cluster (IPC) Instrument Panel Cluster (IPC). TEST the system for normal operation.

No
The system is operating correctly at this time. The DTC may have been set due to high network traffic or an intermittent fault condition.

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