Pinpoint Test B: DTC C1724
Vehicle Dynamic Suspension
Pinpoint Tests
Pinpoint Test B: DTC C1724
Refer to Wiring Diagram Set 41, Vehicle Dynamic Suspension for schematic and connector information. Diagrams By Number
Normal Operation
The 2 rear height sensors receive a 5-volt reference voltage from the Vehicle Dynamics Module (VDM) along circuit LCL12 (VT/OG), both sensors share a common return path along circuit RCL12 (GN/WH). The RR sensor sends the suspension height voltage back to the VDM along circuit VCL12 (WH/VT) and the LR sensor sends the suspension height voltage back to the module along circuit VCL13 (BN/BU). The VDM monitors the 2 height sensors and makes adjustments to the rear suspension based on sensor input.
- DTC C1724 (Air Suspension Height Sensor Power Circuit Failure) - This DTC can be set during normal operation and during the VDM on-demand self test. DTC C1724 will set during normal operation if the ignition key is in the RUN position and the height sensor supply voltage is not at the expected level for more than 2 minutes. DTC C1724 will set during the on-demand self test if the height sensor voltage is not detected after being enabled during the test.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Height sensor(s)
- VDM
PINPOINT TEST B: DTC C1724
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.
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B1 CHECK THE AIR SUSPENSION HEIGHT SENSOR VOLTAGE PIDs
- Disable the air suspension system. Refer to Air Suspension System Disable/Enable Air Suspension System Disable/Enable.
- Connect the scan tool.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: DataLogger VDM.
- Disconnect the sensor arm linkage from both rear air suspension height sensors.
- NOTE: The voltage will increase as the suspension is compressed.
- Slowly move the height sensors through their full range of travel up and down while monitoring the following PIDs:
- Left Rear Height Sensor Voltage (LR_HEIGHT)
- Right Rear Height Sensor Voltage (RR_HEIGHT)
- Do the voltages vary from approximately 0.50 volt and 4.50 volts?
Yes
INSPECT the height sensor electrical connectors for corrosion and damage, REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.
No
CONNECT the sensor arm linkages to the height sensors.
For the LR height sensor, GO to B2.
For the RR height sensor, GO to B3.
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B2 CHECK FOR VDM OUTPUT (LR HEIGHT SENSOR VOLTAGE)
- Ignition OFF.
- Disconnect: LR Height Sensor C4092.
- Ignition ON.
- Measure the voltage between LR height sensor C4092-3, circuit LCL12 (VT/OG), harness side and ground.
- Are 5 volts present?
Yes
GO to B3.
No
If less than 5 volts are present, GO to B4. If more than 5 volts are present, GO to B6.
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B3 CHECK FOR VDM OUTPUT (RR HEIGHT SENSOR VOLTAGE)
- Ignition OFF.
- Disconnect: RR Height Sensor C4093.
- Ignition ON.
- Measure the voltage between RR height sensor C4093-3, circuit LCL12 (VT/OG), harness side and ground.
- Are 5 volts present?
Yes
GO to B7.
No
If less than 5 volts are present, GO to B4. If more than 5 volts are present, GO to B6.
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B4 CHECK CIRCUIT LCL12 (VT/OG) FOR AN OPEN
- Ignition OFF.
- Disconnect: VDM C2131b.
- For the RR height sensor, measure the resistance between VDM C2131b-4, circuit LCL12 (VT/OG), harness side and RR height sensor C4093-3, circuit LCL12 (VT/OG), harness side.
- For the LR height sensor, measure the resistance between VDM C2131b-4, circuit LCL12 (VT/OG), harness side and LR height sensor C4092-3, circuit LCL12 (VT/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to B5.
No
REPAIR circuit LCL12 (VT/OG). CLEAR the DTCs. REPEAT the self-test.
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B5 CHECK CIRCUIT LCL12 (VT/OG) FOR A SHORT TO GROUND
- For the RR height sensor, measure the resistance between RR height sensor C4093-3, circuit LCL12 (VT/OG), harness side and ground.
- For the LR height sensor, measure the resistance between LR height sensor C4092-3, circuit LCL12 (VT/OG), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to B7.
No
REPAIR circuit LCL12 (VT/OG). CLEAR the DTCs. REPEAT the self-test.
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B6 CHECK CIRCUIT LCL12 (VT/OG) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: VDM C2131b.
- Ignition ON.
- For the LR height sensor, measure the voltage between LR height sensor C4092-3, circuit LCL12 (VT/OG), harness side and ground.
- For the RR height sensor, measure the voltage between RR height sensor C4093-3, circuit LCL12 (VT/OG), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit LCL12 (VT/OG). CLEAR the DTCs. REPEAT the self-test.
No
GO to B7.
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B7 CHECK THE VDM CONNECTOR
- Ignition OFF.
- Disconnect: VDM C2131b.
- Check the VDM connector for:
- corrosion.
- pushed-out pins.
- spread terminals.
- Connect: VDM C2131b.
- Make sure the connector is seated correctly, then operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new VDM. REFER to Vehicle Dynamics Module (VDM) Service and Repair. CLEAR the DTCs. REPEAT the self-test.
No
The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector.
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