Pinpoint Test I: Excessive Air Compressor Noise
Vehicle Dynamic Suspension
Pinpoint Tests
Pinpoint Test I: Excessive Air Compressor Noise
Normal Operation
The air compressor is isolated from the rest of the vehicle and other components by 3 rubber isolators and a bracket. The bracket is mounted to the vehicle using 3 rubber isolators with metal inserts. The air compressor should not be in contact with the vehicle or other components.
This pinpoint test is intended to diagnose the following:
- Compressor bracket
- Bracket isolators
- Compressor mounts
- Component routing
- Wire harness routing
PINPOINT TEST I: EXCESSIVE AIR COMPRESSOR NOISE
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I1 CHECK FOR THE AIR COMPRESSOR AND/OR THE AIR COMPRESSOR WIRING CONTACTING OTHER COMPONENTS
- Check the air compressor wiring to see if it is contacting other components inside the engine compartment at any place other than the mounting points.
- Check for anything contacting the air compressor (other wire harnesses, air tubes, hoses, loose fasteners, stones or other foreign material).
- Check for any contact between the wire harness and other compressor components.
- Is any portion of the wire harness contacting the compressor motor components or is anything contacting the compressor assembly other than the mounts?
Yes
REMOVE the air compressor assembly, REFER to Air Suspension Compressor Service and Repair. ADJUST the air compressor wiring harness so that it does not contact the compressor motor or FASTEN/REMOVE objects so they no longer contact the air compressor assembly.
INSTALL the air compressor assembly, REFER to Air Suspension Compressor Service and Repair. TEST the system for normal operation.
No
GO to I2.
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I2 CHECK FOR A BENT AIR COMPRESSOR BRACKET
- Check the air compressor bracket for any damage/bends that may contact other components within the engine compartment.
- Check the bracket rubber isolators and inserts for any excessive wear or damage.
- Is the air compressor bracket making contact with other components or are the bracket isolators damaged?
Yes
INSTALL a new air compressor assembly or REPAIR other components as necessary. REFER to Air Suspension Compressor Service and Repair. TEST the system for normal operation.
No
GO to I3.
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I3 CHECK THE AIR COMPRESSOR MOUNTS FOR DAMAGE
- Check the air compressor mounts for signs of cracks or tearing away from the inner sleeve.
- Is damage present in the mounts?
Yes
INSTALL a new air compressor assembly. REFER to Air Suspension Compressor Service and Repair. TEST the system for normal operation.
No
GO to I4.
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I4 CHECK THE AIR COMPRESSOR FOR NOISE
NOTICE: Do not run the air compressor for more than 3 minutes. The air compressor can overheat and stop operating due to an internal temperature sensitive thermal breaker. The Vehicle Dynamics Module (VDM) will limit run time to protect the air compressor. When DTC C1964 is present, the compressor will not operate for approximately 10 minutes.
- Remove the air compressor assembly, but leave it connected electrically. Refer to Air Suspension Compressor Service and Repair.
- Connect the scan tool.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: DataLogger VDM.
- Toggle the VDM air compressor (COMPRESSR) active command ON.
- Is the air compressor exhibiting any unusual noise?
Yes
TOGGLE the COMPRESSR active command OFF. INSTALL a new air compressor. REFER to Air Suspension Compressor Service and Repair. TEST the system for normal operation.
No
TOGGLE the COMPRESSR active command OFF. RECHECK the mountings and bracket for damage. If damaged, INSTALL a new air compressor bracket. REFER to Air Suspension Compressor Service and Repair. TEST the system for normal operation.
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