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 Ac: U0140:00
- Refer to Wiring Diagrams MANUAL CLIMATE CONTROL SYSTEM
for schematic and connector information.
Normal Operation and Fault Conditions
The ACCM and the HVAC control module communicate with the BCM over the CAN. If messages are missing or not received from the BCM, the climate control system may not operate not operate correctly. REFER to: Climate Control System - Vehicles With: Electronic Manual Temperature Control (EMTC) - System Operation and Component Description .
Inspect for loose or corroded ACCM, BCM and HVAC control module connections.
DTC Fault Trigger Conditions
DTC Description Fault Trigger Condition ACCM U0140:00 Lost Communication With Body Control Module: No Sub Type Information Sets in continuous memory when the ACCM detects network messages are missing from the BCM for more than 5 seconds. HVAC U0140:00 Lost Communication With Body Control Module: No Sub Type Information Sets in continuous memory when the HVAC control module detects network messages are missing from the BCM for more than 5 seconds. Possible Sources
- Network communication concern
- Wiring, terminals or connectors
- Over or undervoltage concerns
- ACCM
- HVAC control module
- BCM
- AC1 VERIFY THE CONCERN
- Ignition ON.
- Verify there is an observable symptom present.
Is an observable symptom present?
Yes GO to AC2 No CLEAR the DTC. The system is operating correctly at this time. The DTC may have been set due to high network traffic or an intermittent fault condition. - AC2 CHECK THE NETWORK COMMUNICATION
- Using a diagnostic scan tool, carry out the network test.
Does the BCM pass the network test?
Yes GO to AC3 No REFER to: Controller Area Network (CAN) Module Communications Network . - AC3 CHECK FOR NON-NETWORK DIAGNOSTIC TROUBLE CODES (DTCS)
- Using a diagnostic scan tool, carry out the self-test for the module in question (ACCM or HVAC control module) setting the DTC.
Are any non-network Diagnostic Trouble Codes (DTCs) present?
Yes DIAGNOSE all non-network Diagnostic Trouble Codes (DTCs) first. REFER to the appropriate DTC Chart in this information. No GO to AC4 - AC4 CHECK FOR NON-NETWORK BCM (BODY CONTROL MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)
- Using a diagnostic scan tool, carry out the BCM self-test.
Are any non-network Diagnostic Trouble Codes (DTCs) present?
Yes REFER to: Body Control Module (BCM) . No GO to AC5 - AC5 RECHECK FOR DTC (DIAGNOSTIC TROUBLE CODE) U0140:00
- Using a diagnostic scan tool, clear the Diagnostic Trouble Codes (DTCs) for the module in question (ACCM, or HVAC control module) setting the DTC.
- Ignition OFF.
- Ignition ON.
- Wait 10 seconds.
- Using a diagnostic scan tool, carry out the self-test for the module in question (ACCM or HVAC control module) setting the DTC.
Is DTC U0140:00 still present?
Yes GO to AC6 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. - AC6 CHECK FOR OTHER CAUSES OF NETWORK COMMUNICATION CONCERNNOTE: If new modules were installed prior to the Diagnostic Trouble Code (DTC) being set, the module configuration can be incorrectly set during the Programmable Module Installation (PMI) or the Programmable Module Installation (PMI) may not have been carried out.
- Check the vehicle service history for recent service actions related to the BCM and the module in question (ACCM or HVAC control module) setting the DTC. If recent service history is found:
- verify correct replacement module was installed
- vehicle parts build list 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 vehicle with concern
- return the swapped module to source vehicle and obtain new replacement module
- 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 AC7 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 BCM and the module in question (ACCM or HVAC control module) setting the DTC. If recent service history is found:
- AC7 CHECK FOR CORRECT BCM (BODY CONTROL MODULE) OPERATION
- Ignition OFF.
- Disconnect and inspect all BCM electrical connectors (if not previously disconnected).
- Repair:
- corrosion (install new connector or terminal - clean module pins)
- damaged or bent pins - install new terminals or pins
- pushed-out pins - install new pins as necessary
- Connect all BCM electrical 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 BCM. REFER to: Body Control Module (BCM) . No The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. 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.