U0105 Lost Communication With Fuel Injector Control Module (FICM)

U0105 Lost Communication With Fuel Injector Control Module (FICM)

OBD-II DTC Datasheet

Lost Communication With Fuel Injector Control Module (FICM)

What does this mean?

This is a generic communications DTC that applies to most makes and models of vehicles, including but not limited to Dodge, Ram, Chevrolet, Ford, GMC, and VW. This code means that the fuel injector control module (FICM) and other control modules on the vehicle are not communicating with each other.

The circuitry most commonly used for communication is known as Controller Area Bus communication, or simply the CAN bus. Without this CAN bus, control modules cannot communicate and your scan tool may not receive information from the vehicle, depending on which circuit is involved.

The FICM controls the injectors based on information received from the powertrain control module (PCM). If information is not received, fuel injection is not performed. These modules are more commonly used in diesels, although their use in direct injection gasoline engines is starting to rise.

Troubleshooting steps may vary depending on the manufacturer, the type of communication system, the number of wires, and the colors of the wires in the communication system.

symptoms

Symptoms of a U0105 engine code may include:

• Malfunction Indicator Light (MIL) is on
• The car starts but does not move
• If the engine is running:
  • Uncertainty about lack of strength
  • Low productivity
  • Misfire in cylinders (rough operation)

reasons

Usually the reason for installing this code is:

• Open in CAN + bus circuit
• Open in the CAN bus - electrical circuit
• Short circuit to power in any CAN bus circuit
• Short to ground in any CAN bus circuit
• Rarely - the control module is faulty

Diagnostic and repair procedures

A good starting point is always to check the Technical Service Bulletins (TSB) for your particular vehicle. Your problem may be a known issue with a known manufacturer-released fix and could save you time and money while troubleshooting.

First, look for other DTCs. If any of these are bus communication or battery / ignition related, diagnose them first. Misdiagnosis is known to occur if you diagnose the U0105 code before any of the major codes are thoroughly diagnosed and rejected.

If your scan tool can access trouble codes and the only code you are getting from other modules is U0105, try contacting the FICM. If you can access the codes from the FICM, then code U0105 is either intermittent or a memory code. If the FICM module cannot be contacted, then code U0105 set by other modules is active and the problem already exists.

The most common failure is a loss of power or ground.

Check all fuses supplying the FICM on this vehicle. Check all grounds for the FICM. Locate ground anchorage points on the vehicle and make sure these connections are clean and secure. If necessary, remove them, take a small wire bristle brush and baking soda / water solution and clean each one, both the connector and the place where it connects.

If any repairs have been made, clear the diagnostic trouble codes from all modules that set the code in memory and see if U0105 returns or you can contact the CC module. If no code is returned or communication with CCM is restored, the problem is most likely a fuse / connection issue.

If any repairs have been made, clear the DTCs from all modules that set the code in memory and see if U0105 returns or you can contact the FICM. If no code is returned or communication with the FICM is restored, the problem is most likely a fuse / connection issue.

If the code returns, look for the CAN bus communication connections on your specific vehicle, especially the FICM connector. Disconnect the negative battery cable before disconnecting the connector on the FICM. Once detected, visually inspect the connectors and wiring. Look for scratches, scuffs, exposed wires, burn marks, or molten plastic. Disconnect the connectors and carefully inspect the terminals (metal parts) inside the connectors. See if they look burnt or have a green tint indicating corrosion. If you need to clean the terminals, use an electrical contact cleaner and a plastic bristle brush. Allow to dry and apply dielectric silicone grease where the terminals touch.

Perform these few voltage checks before connecting the connectors back to the FICM. You will need access to a digital volt/ohmmeter (DVOM). Make sure you have power and ground on the FICM. Access the wiring diagram and determine where the main power and ground supplies enter the FICM. Connect the battery before continuing with the FICM still disabled. Connect the red lead of your voltmeter to each B+ (battery voltage) power supply plugged into the FICM connector, and the black lead of your voltmeter to a good ground (if unsure, battery negative always works). You should see the battery voltage reading. Make sure you have a good reason. Connect the red lead of the voltmeter to the battery positive (B+) and the black lead to each ground circuit. Once again, you should see the battery voltage every time you connect. If not, repair the power or ground circuit.

Then check the two communication circuits. Locate CAN C+ (or HSCAN+) and CAN C- (or HSCAN - circuit). With the black wire of the voltmeter connected to a good ground, connect the red wire to CAN C+. With the key on and engine off, you should see about 2.6 volts with little fluctuation. Then connect the red wire of the voltmeter to the CAN C- circuit. You should see about 2.4 volts with little fluctuation.

If all tests pass and communication is still not possible, or you were unable to reset DTC U0105, the only thing you can do is seek help from a trained automotive diagnostician as this will indicate a faulty FICM module. Most of these FICMs must be programmed or calibrated for the vehicle in order to be properly installed.

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