Pinpoint Test U: The Tire Pressure Monitoring System (TPMS) Warning Indicator Is Never/Always On

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

Pinpoint Test U: The Tire Pressure Monitoring System (TPMS) Warning Indicator is Never/Always On

Normal Operation

Each road tire is equipped with a tire pressure sensor fastened to the inside rim of the wheel. The tire-mounted pressure sensors transmit signals to the Smart Junction Box (SJB) by using the valve stem as an antenna. These signals are sent approximately every 60 seconds when the vehicle speed exceeds 32 km/h (20 mph). The SJB compares each tire pressure sensor signal against low and high pressure limits. If the SJB determines that the tire pressure has exceeded the limit, the SJB communicates over the Medium Speed Controller Area Network (MS-CAN) to the Instrument Cluster (IC), which then illuminates the Tire Pressure Monitoring System (TPMS) warning indicator. If the TPMS status message is missing for more than 5 seconds, the IC sets DTC U0140 and flashes the TPMS indicator for approximately 70 seconds then turns on the TPMS indicator.

This pinpoint test is intended to diagnose the following:

- TPMS concern
- SJB
- IC



PINPOINT TEST U: THE TPMS WARNING INDICATOR IS NEVER/ALWAYS ON

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U1 CHECK THE TIRE PRESSURE


- Verify that the tire pressure in all tires meets the recommended tire pressures on the vehicle certification label. Refer to Vehicle Identification Codes.
- Do all the tires meet the recommended tire pressures?

Yes
GO to U2.

No
CORRECT the tire pressures. TEST the system for normal operation.

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U2 CHECK FOR MESSAGE CENTER TPMS WARNING MESSAGES


- Ignition ON.
- Monitor the message center for TPMS related warning messages.
- Are any TPMS warning messages displayed in the message center?

Yes
REFER to Wheels and Tires.

No
GO to U3.

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U3 RETRIEVE THE RECORDED DTCs FROM THE SJB SELF-TEST


- Check for recorded SJB DTCs from the self-test.
- Are any TPMS related SJB DTCs recorded?

Yes
REFER to Body Control Systems.

No
GO to U4.

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U4 CARRY OUT THE IC INDICATOR LAMP ACTIVE COMMAND USING THE SCAN TOOL


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger.
- Select the IC TPMS warning indicator (TIRE_PRES) active command. Command the TPMS warning indicator on and off. Observe the low tire pressure warning indicator.
- Does the TPMS warning indicator illuminate when commanded on, and turn off when commanded off?

Yes
INSTALL a new SJB. REFER to Body Control Systems. TEST the system for normal operation.

No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.

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