Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Pinpoint Test BD: U0424-86
- Normal Operation and Fault Conditions
REFER to: Lane Keeping System - System Operation and Component Description .
DTC Fault Trigger Conditions
DTC Description Fault Trigger Condition IPMA U0424:86 Invalid Data Received From HVAC Control Module: Signal Invalid This continuous memory DTC sets in the IPMA when invalid data received from HVAC module through GWM. Possible Sources
- Communication concern
- GWM
- HVAC module
- BD1 VERIFY THE CUSTOMER CONCERN
- Ignition ON.
- Verify there is an observable symptom present.
Is an observable symptom present?
Yes GO to BD2 No CLEAR the DTC. The system is operating normally at this time. The DTC may have been set due to high network traffic or an intermittent fault condition. - BD2 CHECK THE COMMUNICATION NETWORK
- Using a diagnostic scan tool, carry out the network test.
Does the HVAC module pass the network test?
Yes GO to BD3 No REFER to: Controller Area Network (CAN) Module Communications Network . REFER to: Ethernet Module Communications Network . - BD3 CARRY OUT THE IPMA (IMAGE PROCESSING MODULE A) SELF-TEST
- Using a diagnostic scan tool, carry out the IPMA self-test.
Are any network Diagnostic Trouble Codes (DTCs) present?
Yes DIAGNOSE all non-network Diagnostic Trouble Codes (DTCs). REFER to the IPMA DTC Chart. No GO to BD4 - BD4 CHECK THE GWM (GATEWAY MODULE A) DIAGNOSTIC TROUBLE CODES (DTCS)
- Using a diagnostic scan tool, check the GWM Continuous Memory Diagnostic Trouble Codes (CMDTCs).
Are any Diagnostic Trouble Codes (DTCs) recorded?
Yes REFER to: Controller Area Network (CAN) Module Communications Network . REFER to: Ethernet Module Communications Network . No GO to BD5 - BD5 CARRY OUT THE HVAC (HEATING, VENTILATION AND AIR CONDITIONING) MODULE SELF-TEST
- Using a diagnostic scan tool, carry out the HVAC module self-test.
Are any network Diagnostic Trouble Codes (DTCs) present?
Yes REFER to: Climate Control System - Vehicles With: Dual Automatic Temperature Control (DATC) . REFER to: Climate Control System - Vehicles With: Electronic Manual Temperature Control (EMTC) . No GO to BD6 - BD6 RECHECK THE IPMA (IMAGE PROCESSING MODULE A) DIAGNOSTIC TROUBLE CODES (DTCS)
- Using a diagnostic scan tool, clear the IPMA Diagnostic Trouble Codes (DTCs).
- Ignition OFF.
- Ignition ON.
- Wait 10 seconds.
- Using a diagnostic scan tool, carry out the continuous memory self-test.
- Check the IPMA Diagnostic Trouble Codes (DTCs).
Is DTC U0424:86 '
Yes GO to BD7 No The system is operating correctly at this time. The DTC may have been set due to high network traffic, or an intermittent fault condition. - BD7 CHECK FOR OTHER CAUSES OF COMMUNICATION NETWORK CONCERN
- CHECK the vehicle service history for recent service actions related to the HVAC module or IPMA. If recent service history is found:
- verify correct replacement module was installed
- vehicle parts build may be used to verify correct part fitment
- verify the configuration of replacement module was correct
- re-configure module using as-built data if prior configuration is suspect
- verify the module was not obtained from a like vehicle and installed into customer vehicle
- return the swapped module to source vehicle and obtain new replacement module
- if a new replacement module is installed, CARRY OUT PMI using as-built data
- verify correct replacement module was installed
- Operate the system and determine if the observable symptom is still present.
Is the observable symptom still present?
Yes GO to BD8 No The system is operating correctly at this time. The concern may have been due to incorrect parts replacement procedures or incorrect module configuration. - CHECK the vehicle service history for recent service actions related to the HVAC module or IPMA. If recent service history is found:
- BD8 CHECK FOR CORRECT HVAC (HEATING, VENTILATION AND AIR CONDITIONING) MODULE OPERATION
- Ignition OFF.
- Disconnect and inspect the HVAC module connectors.
- Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary
- Reconnect the HVAC module connectors. Make sure they seat and latch correctly.
- Operate the system and determine if the concern is still present.
Is the concern still present?
Yes CHECK OASIS for any applicable service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new HVAC module. REFER to: Heating, Ventilation and Air Conditioning (HVAC) Control Module . No The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.