U1108 — SCP (J1850) Invalid or Missing Data for Electric Traction Drive (Inverter) #

Note: The exact wording of this code may vary by manufacturer. Always refer to your vehicle’s service manual for the OEM-specific description.

• U1108 — Electric Traction Drive Inverter Data Invalid/Missing (Chrysler)
• U1108 — Missing Data for Inverter (Fiat/Jeep)
• U1108 — Traction Drive Communication Loss (Dodge)

Summary of DTC U1108 #

The U1108 diagnostic trouble code (DTC) signals that the vehicle’s control module has not received valid data from the Electric Traction Drive Inverter. The inverter is a crucial component in hybrid and electric vehicles, converting DC battery power to AC for the electric motor. The communication protocol involved, SCP (Standard Corporate Protocol) J1850, manages data transmission between modules. When the inverter data is missing or invalid, it can trigger performance issues, warning lights, and limit the vehicle’s ability to operate in electric mode. This code can be intermittent or persistent, depending on the underlying electrical or communication problem.

Common Symptoms for DTC U1108 #

When code U1108 is stored, you may notice several performance changes or alerts. The most common symptom is the illumination of the Check Engine Light or a hybrid system warning indicator. In some cases, the vehicle may restrict power or enter a “limp” mode to protect the drivetrain. Below are frequent symptoms:

• Check Engine or Service Hybrid System light on
• Reduced electric drive performance
• Loss of regenerative braking
• Limited or no electric mode operation
• Delayed or harsh switching between power sources
• Unusual noises from the traction inverter area

Most Likely Causes for U1108 #

The U1108 code points to a problem with data transmission between the inverter and other control modules. Causes range from simple connection issues to complex electronic failures. Listed below in order of likelihood:

1. Loose, corroded, or damaged wiring/connectors at the inverter or along the data bus
2. Faulty Electric Traction Drive Inverter itself
3. Data communication errors in the SCP (J1850) network
4. Control Module (PCM/BCM/Hybrid Control Module) malfunction
5. Aftermarket device interference (e.g., alarm or remote start systems spliced into data lines)
6. Low or unstable battery voltage affecting module communication

Step-by-Step Diagnosis for Code U1108 #

Accurate diagnosis requires following a systematic process, starting from the simplest checks. Always take safety precautions when working with high-voltage hybrid or electric vehicle components.

• 1. Scan the vehicle with an OEM-compatible diagnostic tool to confirm the U1108 code and check for related DTCs.
• 2. Visually inspect all wiring and connectors to the inverter and along the data bus for loose, corroded, or damaged terminals.
• 3. Check battery voltage (both 12V and high-voltage system) and charging system integrity.
• 4. Test data bus integrity using a multimeter or oscilloscope for correct signal patterns and resistance.
• 5. Disconnect aftermarket accessories that may be interfering with data lines and retest.
• 6. If wiring and power supply are good, use scan tool live data to check inverter communication status.
• 7. Consult OEM service procedures for module reprogramming or replacement if a control module or inverter is suspected faulty.

Possible Repairs for U1108 #

Repairs should directly address the diagnosed root cause. Some fixes are straightforward, while others may require specialized tools or components.

• Repair or replace damaged wiring/connectors (most common fix)
• Secure or clean loose/corroded terminals at the inverter or control modules
• Replace a faulty Electric Traction Drive Inverter (may require OEM calibration)
• Replace or reprogram a malfunctioning control module
• Remove interfering aftermarket devices from communication lines
• Restore proper battery voltage and charging system operation

Is It Safe to Drive with Code U1108? #

Driving is limited and not recommended until the issue is resolved. U1108 can cause loss of electric drive or reduced power, potentially leaving you stranded or causing unsafe driving conditions, especially in traffic or at highway speeds. In rare cases, the vehicle may shut down unexpectedly or lose regenerative braking. For your safety and to avoid further damage, have the system diagnosed and repaired promptly.

Vehicles Most Commonly Affected by U1108 #

This code is most often seen on hybrid and electric vehicles from manufacturers using SCP/J1850 data bus protocols, especially those in the Chrysler, Dodge, Jeep, and Fiat families. It may also appear in other brands with similar inverter control strategies.

• Chrysler Pacifica Hybrid
• Fiat 500e
• Jeep Renegade PHEV
• Dodge Ram Hybrid
• Other Fiat-Chrysler (FCA) hybrid/electric models

Common Mistakes & Best Practices for U1108 #

Avoiding misdiagnosis saves time and money. Here are common pitfalls and tips to keep your troubleshooting on track:

• Replacing the inverter or control module before checking wiring and connectors
• Ignoring low battery voltage or intermittent charging issues
• Overlooking aftermarket electronics as a potential cause
• Not following OEM diagnostic flowcharts
• Best practice: Always document the freeze frame data and all present DTCs before clearing codes or disconnecting the battery
• Verify repair with a test drive and rescan to ensure the code does not return

Quick FAQ for DTC U1108 #

Having questions is normal—here are answers to the most common ones:

• Q: Can a weak 12V battery really cause U1108?
  A: Yes. If the 12V system sags, it can disrupt module communication, triggering U1108 or similar codes.
• Q: Will clearing the code make my hybrid system work again?
  A: Not likely. The code will return if the underlying issue isn’t resolved—focus on diagnosis, not just erasing the code.