Pinpoint Test D: DTC U0100

Smart Junction Box (SJB)

Pinpoint Tests

Pinpoint Test D: DTC U0100

Refer to Wiring Diagram Set 14, Module Communications Network for schematic and connector information. Diagrams By Number

Normal Operation

The Smart Junction Box (SJB) and the PCM communicate using the High Speed Controller Area Network (HS-CAN) between the Instrument Cluster (IC) and the Medium Speed Controller Area Network (MS-CAN) between the IC and the PCM. Messages are exchanged between the modules on the 2 networks for the purposes of determining what functions are being carried out.

- DTC U0100 (Lost Communication With ECM/PCM) - set by the SJB if the ignition is in RUN, the SJB supply voltage is greater than 10.5 volts, less than 15 volts and if the engine rpm, vehicle speed or throttle position messages are missing.

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 Information Bus.

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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/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/U0100:00 set in the 4X4 control module, ABS module, IC, SJB or RCM?

Yes
INSTALL a new PCM. REFER to Computers and Control Systems.

No
INSTALL a new SJB. REFER to Smart Junction Box (SJB) Service and Repair.

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