Rear Audio and Temperature Control (RATC) Module

Rear Audio and Temperature Control (RATC) Module

Pinpoint Tests


Pinpoint Test J: DTC U1178

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

This pinpoint test is intended to diagnose the following:


- Module communication
- RATC module
- HVAC module



PINPOINT TEST J: DTC U1178

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J1 VERIFY CUSTOMER CONCERN


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

Yes
GO to J2.

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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J2 CHECK THE COMMUNICATION NETWORK


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

Yes
GO to J3.

No
REFER to Information Bus.

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J3 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 Service and Repair. TEST the system for normal operation. REPEAT the RATC module self-test.

If DTC U1178 is still present, INSTALL a new HVAC module. REFER to Heating and Air Conditioning.

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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