Rear Audio and Temperature Control (RATC) Module

Rear Audio and Temperature Control (RATC) Module

Pinpoint Tests

Pinpoint Test F: DTC U1178

Normal Operation
- DTC U1178 (SCP (J1850) Invalid or Missing Data for Climate Control (HVAC)) - sets when the Rear Audio and Temperature Control (RATC) module is missing messages from the HVAC module.

This pinpoint test is intended to diagnose the following:

- Module communication
- RATC module
- HVAC module


PINPOINT TEST F: DTC U1178

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F1 VERIFY CUSTOMER CONCERN


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

Yes
GO to F2.

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

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F2 CHECK THE COMMUNICATION NETWORK


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

Yes
GO to F3.

No
REFER to Module Communications Network Testing and Inspection.

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F3 RECHECK THE RATC MODULE 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 the PMI may not have been carried out.

- Clear the DTCs. Repeat the RATC module self-test.
- Is DTC U1178 still present?

Yes
INSTALL a new RATC module. REFER to Rear Audio and Temperature Control (RATC) Module Rear Audio and Temperature Control (RATC) Module. TEST the system for normal operation.

If DTC U1178 is still present, INSTALL a new HVAC module. REFER to Climate Control Service and Repair.

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

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