Pinpoint Test D: DTC U0100

Smart Junction Box (SJB)

Pinpoint Tests

Pinpoint Test D: DTC U0100

Normal Operation
- DTC U0100 (Lost Communication With ECM/PCM) - sets when the SJB if detects the engine rpm, vehicle speed or throttle position messages are missing from the PCM.

This pinpoint test is intended to diagnose the following:


- Module communication
- SJB
- PCM

PINPOINT TEST D: DTC U0100

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D1 VERIFY CUSTOMER CONCERN

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

Yes
GO to D2.

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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D2 CHECK THE COMMUNICATION NETWORK

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

Yes
GO to D3.

No
REFER to Module Communications Network Testing and Inspection.

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D3 RETRIEVE THE RECORDED DTCs FROM THE SELF-TEST

- Check for recorded SJB DTCs from the self-test.
- Is DTC B1317 or DTC B1318 recorded?

Yes
For DTC B1317, GO to Pinpoint Test B Pinpoint Test B: DTC B1317. For DTC B1318, GO to Pinpoint Test C. Pinpoint Test C: DTC B1318

No
GO to D4.

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D4 RECHECK THE SJB DTCs

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

- Clear the DTCs. Repeat the SJB self-test.
- Is DTC U0100 still present?

Yes
GO to D5.

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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D5 CHECK FOR DTC U0100 OR DTC U0100:00 SET IN OTHER MODULES

- Clear all DTCs.
- Ignition OFF.
- Ignition ON.
- Wait 10 seconds.
- Enter the following diagnostic mode on the scan tool: Self-Test.
- Retrieve the continuous memory DTCs from all modules.
- Is DTC U0100 or DTC U0100:00 set in any other module?

Yes
INSTALL a new PCM. REFER to Electronic Engine Controls Service and Repair. TEST the system for normal operation.

No
INSTALL a new SJB. REFER to Smart Junction Box (SJB) Service and Repair. TEST the system for normal operation.

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