The U0107: Lost Communication with Throttle Actuator Control Module indicates a communication problem between the vehicle’s main computer (ECM) and the Throttle Actuator Control (TAC) module. This module is responsible for controlling the throttle body’s position based on the driver’s input. When communication is lost, the ECM cannot control the throttle, leading to potential stalling or failure to accelerate.
U0107 quick overview
| Meaning | U0107: Lost Communication with Throttle Actuator Control Module |
| Is it serious? | This code is serious as it may lead to the vehicle not responding to throttle input, potentially causing stalling or lack of acceleration. |
| Possible causes | – Faulty Throttle Actuator Control (TAC) module – Damaged or disconnected wiring to the TAC module – Poor ground connections related to the throttle system – Failing Engine Control Module (ECM) – Voltage drops in the electrical system affecting the TAC module – Faulty or loose connectors at the throttle body or ECM |
| How to diagnose? | Inspect Ground Connections: Check all engine and chassis grounds for security and cleanliness. Examine Wiring Harness: Look for any damage or wear in the wiring harness, especially near heat sources. Check Module Power and Grounds: Verify that TAC and ECM have proper power and ground supply. Perform Voltage Drop Tests: Identify any voltage drops that could affect the throttle system’s performance. Inspect Connectors: Examine connectors at the throttle body and ECM for damage or corrosion. Consider Module Replacement: If wiring and connections are fine, evaluate the condition of the TAC module or ECM. Reflash or Replace ECM: If ECM is suspected, consider reflashing or replacing it. Wiggle Test Wiring: Conduct a wiggle test to uncover any intermittent faults in wiring. |
U0107 Meaning
This code means your car’s computer can’t talk to the part that controls the engine’s throttle. This might cause your car to stall or not speed up properly. It’s important to fix this to make sure your car runs safely and responds correctly when you press the gas pedal. The usual steps to fix this involve checking all the wires and connections, and sometimes replacing the parts that control the throttle or the car’s main computer.
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
How to fix U0107 – learn from mechanics
I looked into U0107 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: GMC
Vehicle Information: 2005 GMC W3500 Forward W3S042 6.0L
Issue + Repair History: The vehicle had an intermittent issue with not shutting off. The dash would go out, but the truck would continue running. Flipping the bright dim switch or turning it off with the lights on would sometimes shut it off. Code U0107 was recurring. Cleaned all grounds, replaced the ignition switch and electronic throttle control, and did the latest reprogram with TIS.
Other OBD2 Codes + Test Results: Code U0107 – Lost Communication With Throttle Actuator Control Module
Suggestions to Fix Issue:
- Check the alternator and battery charging system.
- Inspect all wiring for voltage feedback.
- Consider possible issues with the ignition switch not being clocked correctly.
- Investigate if the engine compartment fuse box is causing the issue.
Final Fix: The problem was resolved by addressing a bad ground on the back of the engine.
Case #2: Isuzu
Vehicle Information: 2004 Isuzu NPR 6.0L Gas
Issue + Repair History: The vehicle had an issue with not shutting down with the key and no throttle response. Pulling the alternator wire corrected the problem temporarily. Alternator replacement didn’t help. Issue resolved after a DTC reset, but the DTC returned after one cycle with the same symptoms. Checked all grounds and connectors, and was in the process of checking for voltage drops and power to TCM, ECM.
Other OBD2 Codes + Test Results: Code U0107
Suggestions to Fix Issue:
- Remove the ignition relay in the instrument panel relay box to test if it stalls the engine.
- Check for good ground at pin 4 of the ignition relay and battery voltage at pin 2.
- Inspect TAC wiring and voltages.
- Tilt the cab up to see if the problem resolves, indicating potential wiring harness issues.
Final Fix: The issue was resolved by addressing a voltage drop between the ignition switch and number 3 fuse. The ignition relay was bad, causing the voltage drop. Replacing the ignition relay fixed the problem. However, it was noted that pulling the alternator wire also temporarily corrected the issue, which was not fully understood.
Case #3: Chevrolet
Vehicle Information: 2004 Chevrolet Silverado 2500 6.0L
Issue + Repair History: The vehicle had issues with poor idle quality and the MIL lamp was on. After replacing the engine with a used one, it showed a code U0107 (lost communication with accelerator control module). The accelerator pedal position sensor and accelerator control module were replaced, but the problem persisted. The fuse and all grounds related to the engine replacement were checked and found to be good. Continuity from the module to the throttle control motor was confirmed.
Other OBD2 Codes + Test Results: Code U0107 – Lost communication with throttle module
Suggestions to Fix Issue:
- Check the grounds on the back of the heads, as they may be broken.
- Ensure the wiring from the APP to the TAC module is intact.
- Conduct a voltage drop on the module’s grounds.
- Check the wiring at the TAC module for pin/connector issues.
- Inspect for voltage feedback from any source when the engine doesn’t shut down.
- Consider reprogramming the PCM or replacing it if other diagnostics don’t yield results.
Final Fix: The issue was resolved by reconnecting a missed ground wire on the back of the engine. Several suggestions had indicated the importance of checking the grounds. Once the ground was connected, the vehicle functioned correctly.
Case #4: Honda
Vehicle Information: 2003 Honda Accord EX 3.0L
Issue + Repair History: The vehicle experienced hesitation and the MIL lamp was on. The throttle body was cleaned and reset, but the issue persisted with the throttle stuck at 7%. A new throttle body unit was installed, but the same issue and code remained.
Other OBD2 Codes + Test Results: Code U0107 – Lost communication with throttle actuator
Suggestions to Fix Issue:
- Check the 15a fuse in the underhood fuse block related to the throttle control module.
Final Fix: The problem was traced back to the throttle by wire driver unit, located in the passenger side footwell near the blower assembly. It was determined that the original throttle body might have shorted out and damaged the driver unit. Replacing the throttle by wire driver unit resolved the issue.
Case #5: Pontiac
Vehicle Information: 2006 Pontiac Grand Prix 3.8L
Issue + Repair History: The car died intermittently with an error message (“no start due to electric throttle fault”) and would restart after key removal and reinsertion. It sometimes set the above codes but had no consistent pattern. The issue was sporadic, occurring right away or sometimes not for a couple of days.
Other OBD2 Codes + Test Results:
U0107 – Loss of communication with throttle body
P0601 – Internal ECM fault
P0606 – Internal fault
Suggestions to Fix Issue:
- Check the wiring to the electronic throttle body and perform wiggle testing for loss of power or ground.
- Check for rippled voltage or bad grounds.
- Disconnect the TAC module and try clearing the PCM codes. If P0601 and P0606 return, consider replacing the PCM.
Final Fix: The issue was resolved by finding and repairing the wiring at the front valve cover that had rubbed through.
How to diagnose U0107
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Advice | Diagnostic Step |
|---|---|
| Check Ground Connections | Inspect and ensure all engine and chassis ground connections are secure and clean. |
| Inspect Wiring Harness | Closely examine the wiring harness for damage, especially near hot or moving parts, and repair any damaged wires. |
| Verify Power and Grounds to Modules | Confirm that all modules related to the throttle system (like ECM and TAC) are receiving proper power and ground. |
| Check for Voltage Drops | Perform voltage drop tests to identify any potential issues with power supply to the throttle system. |
| Inspect Connectors | Examine all related connectors for damage, corrosion, or loose pins, especially at the throttle body and ECM. |
| Consider Module Failure | If wiring and connections are intact, consider the possibility of a failing Throttle Actuator Control (TAC) module or Engine Control Module (ECM). |
| Reflash or Replace ECM | If diagnostics point to an ECM issue and all other components are functioning, consider reflashing or replacing the ECM. |
| Wiggle Test Wiring | Perform a wiggle test on the wiring, especially near the throttle body, to check for intermittent faults. |
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko