Pinpoint Tests AV: DTC U0121:00

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

Pinpoint Test AV: DTC U0121:00

Normal Operation
- DTC U0121:00 (Lost Communication With Anti-Lock Brake System (ABS) Control Module: No Sub-Type Information) - sets in continuous memory 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 5 seconds or longer. 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 AV: DTC U0121:00

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AV1 VERIFY THE CUSTOMER CONCERN

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

Yes
GO to AV2.

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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AV2 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 AV3.

No
REFER to Module Communications Network Testing and Inspection.

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AV3 RETRIEVE THE RECORDED DTCs FROM THE ABS MODULE SELF-TEST

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

Yes
REFER to Vehicle Dynamic Systems Testing and Inspection.

No
GO to AV4.

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AV4 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
For DTC U3003:16, GO to Pinpoint Test BD Pinpoint Tests BD: DTC U3003:16. For DTC U3003:17, GO to Pinpoint Test BE Pinpoint Tests BE: DTC U3003:17.

No
GO to AV5.

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AV5 RECHECK THE IPC DTCs

NOTE: If new modules were installed prior to the DTC being set, the module configuration may be incorrectly set during the Programmable Module Installation (PMI) or the PMI may not have been carried out.

- Clear the DTCs.
- Wait 10 seconds.
- 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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