Fix U0155: Mechanic’s solutions that WORKED

Code U0155: Lost Communication With Instrument Panel Cluster (IPC) Control Module indicates a communication breakdown between the vehicle’s main computer systems and the Instrument Panel Cluster (IPC). This fault often arises due to issues within the vehicle’s internal network, such as wiring problems, module failures, or software glitches.

U0155 quick overview

Meaning	U0155: Lost Communication With Instrument Panel Cluster (IPC) Control Module
Is it serious?	Yes, it can be serious as it affects the communication with the vehicle’s instrument panel, potentially impacting the display of critical vehicle information.
Possible causes	– Faulty Instrument Cluster (IPC) – Instrument Cluster harness is open or shorted – Poor electrical connection in the Instrument Cluster circuit – Faulty Body Control Module (BCM) – Issues in the CAN bus communication network
How to diagnose?	Check for Additional Codes: Look for other related diagnostic trouble codes. Inspect Wiring and Connectors: Examine the IPC and BCM for loose connections or damaged wiring. Test Power and Ground: Verify proper power and ground supply to the IPC and BCM. CAN Bus Inspection: Evaluate the CAN bus network for resistance and continuity issues. Module Testing: Test the functionality of the Instrument Cluster and BCM. Software Update: Check for and install any software updates available for the IPC or BCM.

How to fix U0155 – learn from mechanics

I looked into U0155 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Jeep

Vehicle Information

• 2008 Jeep Wrangler Unlimited X, 3.8L Engine

Issue + Repair History

• Inoperative instrument cluster since battery replacement
• Code U0155 present (communication error with cluster)

Other OBD2 Codes + Test Results

• No additional OBD2 codes or test results mentioned

Suggestions to Fix Issue

• Scope interior bus wires running to the cluster to check for issues
• Check if the radio also goes dead or if it’s just a loss of communication with the Cluster Control Node (CCN)
• Double-check power and ground connections to the cluster with a headlight test
• Determine if the CCN is active on the bus and if other modules are logging DTCs against the CCN

Final Fix

• Replaced the instrument cluster with a new one from Chrysler, which resolved the issue. Suspected that the customer may have attempted to jump-start the car with reverse polarity, causing the cluster to short out.

Case #2: Cadillac

Vehicle Information

• 2008 Cadillac CTS, 3.6L Engine

Issue + Repair History

• Radio, navigation, and lights in the center dash not working
• Initially resolved by pulling and reinstalling all fuses
• Issue recurred; fuses checked but did not resolve the problem
• Code U0155 (lost communication with the Instrument Panel Cluster module) pulled

Other OBD2 Codes + Test Results

• No additional test results mentioned

Suggestions to Fix Issue

• Check the fuse box in the trunk for loose connections
• For non-navigation models, there might be a software update for the radio
• Possible Instrument Panel Cluster (IPC) module failure
• Complete capacitor discharge by disconnecting the battery and touching battery cables together
• Voltage drop test on the ignition switch
• Check connector at the IPC
• Check for poor/chaffed connections or wires behind the radio

Final Fix

• Removed and reinstalled all fuses one by one, which made everything work again. The customer reported that everything continued to work normally thereafter. The exact cause of the issue was not definitively identified.

Case #3: Mazda

Vehicle Information

• 2005 Mazda 6 i, 2.3L Engine

Issue + Repair History

• Vehicle stuck in 3rd gear
• Codes U0101 (loss of communication with TCM) and U0155 (loss of communication with instrument cluster) present
• Transmission starts in first gear when codes are cleared but jumps to third gear upon throttle engagement
• Fluid level correct and in good condition

Other OBD2 Codes + Test Results

• No additional test results mentioned

Suggestions to Fix Issue

• Check power to the transaxle; possible ignition switch issues
• Focus on U codes before condemning the transmission
• Check for potential CAN bus wire or TCM issues
• Determine if communication with TCM is possible; if not, issue might be inside TCM
• Consider possible internal module failure

Final Fix

• No specific repairs made to fix the transmission problem
• After changing the battery, the problem did not reoccur. Test drove for many miles without any codes or problems returning.

Case #4: Ford

Vehicle Information

• 2009 Ford F-150 XLT, 5.4L Engine

Issue + Repair History

• Various warning lights on (TPMS, brake light, SES light)
• No turn signals, AC inoperative
• Communication errors (CAN) and numerous codes in ECM and BCM
• SJB testing suggests issues; possible problem with SJB (Smart Junction Box) but uncertain
• IPC (Instrument Panel Cluster) checked with no apparent concerns
• Resistance readings (CAN network) higher than expected (120 ohms or open vs. expected 60 ohms)

Other OBD2 Codes + Test Results

• Multiple U0155 codes indicating communication issues with various modules
• P1260 theft detected in PCM
• Codes indicating invalid data or loss of communication from IPCM
• All modules seem to be affected by communication errors

Suggestions to Fix Issue

• Compare DTCs to wiring diagram to isolate network faults
• Check for broken wires in the driver’s door harness
• Assess whether the issue is with the high-speed or medium-speed CAN bus
• Check Fuse 27 in the battery junction box
• Consider possibility of IPC being the ‘gateway’ for communication issues

Final Fix

• Replaced the IPC (Instrument Panel Cluster) which restored function to most systems
• Found and repaired an open wire affecting the HVAC system
• After these repairs, the MS CAN was communicating properly with all systems
• Learned valuable lessons from troubleshooting the extensive communication issues

Case #5: Chevrolet

Vehicle Information

• 2007 Chevrolet Suburban 1500 LT, 5.3L Engine

Issue + Repair History

• TPMS light on dash and remote entry not working
• Multiple codes present: U0214, B0121, U0155, U0140, etc.
• No previous relevant repair history

Other OBD2 Codes + Test Results

• Various ‘U’ and ‘B’ codes indicating communication and body system errors

Suggestions to Fix Issue

• Consult repair databases like Mitchell or Alldata for diagnostic procedures
• Reference TSB # 06-08-52-002G for potential reprogramming of the door lock receiver module and key fob replacement
• Consider replacing the RCDLR (Remote Control Door Lock Receiver), known for “Logic Lock” issues, causing TPMS and remote keyless entry problems
• RCDLR is located under the driver side upper garnish molding in the hatch area and requires programming when replaced

Final Fix

• Initially installed a new remote control module which failed to program with Tech 2
• Attempted flashing the BCM (Body Control Module) with an available update, but it didn’t resolve the issue
• Reinstalled the old remote control module, after which everything started working correctly
• The exact cause of the fix remains uncertain, possibly related to the BCM update or reinstallation of the old module

Advice	Diagnostic Step
Check Power and Grounds	Ensure proper power and ground connections to the affected modules.
Scan for Additional Codes	Look for other related diagnostic trouble codes that could indicate a broader issue.
Inspect Wiring and Connectors	Check for damaged wires or loose connectors in the communication network.
Reset/Reprogram Modules	Consider resetting or reprogramming modules like the Body Control Module (BCM).
Replace Faulty Module	If diagnostics point to a specific module failure (like the Instrument Cluster or BCM), consider replacement.
Perform Network Resistance Check	Measure resistance across the network to identify open circuits or resistance issues.
Inspect for Physical Damage	Look for any physical damage to modules or wiring that might affect communication.
Update Module Software	Check for and apply software updates to relevant modules as they can resolve communication issues.