U0147 Lost communication with gateway B
OBD2 Error Codes

U0147 Lost communication with gateway B

U0147 Lost communication with gateway B

OBD-II DTC Datasheet

Lost Communication with Gateway "B"

What does this mean?

This is a generic communication system diagnostic trouble code that applies to most makes and models of vehicles. This code means that gateway module "B" and other control modules on the vehicle do not communicate 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 gateway module is responsible for transferring information from one CAN bus network to other modules on another CAN bus network. Your scan tool can often connect to this gateway module to access both CAN bus networks at the same time to speed up access times.

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 U0147 engine code may include:

  • Malfunction Indicator Lamp (MIL) illuminated
  • The car may or may not start
  • ABS indicator is on
  • TRAC indicator is on (depending on the manufacturer)
  • ESP / ESC indicator is on (depending on the manufacturer)

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
  • Power or ground break on the GATEWAY "B" module - most often
  • 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.

If your scan tool can access trouble codes and the only code you are pulling from other modules is U0147, try accessing the GATEWAY module. If you can access codes from the GATEWAY module, then code U0147 is either intermittent or a memory code. If the codes for the GATEWAY module cannot be accessed, then code U0147 set by other modules is active and the problem already exists.

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

Check all fuses supplying the GATEWAY module on this vehicle. Check all grounds for the GATEWAY module. Locate grounding attachment 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 DTCs from memory and see if U0147 returns or you can contact the GATEWAY module. If no code is returned or communication is restored, the problem is most likely a fuse / connection issue.

If the code returns, look for the CAN C bus connections on your specific vehicle, especially the GATEWAY module connector. Disconnect the negative battery cable before disconnecting the connector on the GATEWAY control module. 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 electrical grease where the terminals touch.

Perform these few voltage checks before plugging the connectors back into the GATEWAY. You will need access to a digital volt-ohmmeter (DVOM). Make sure you have power and ground on the GATEWAY module. Access the wiring diagram and determine where the main power and ground supplies go into the GATEWAY module. Connect the battery before proceeding with the GATEWAY disconnected. Connect the red wire of your voltmeter to each B + (battery voltage) power source going to the connector on the GATEWAY module, and the black wire of your voltmeter to a good ground (if unsure, the negative pole of the battery always works). You can see the battery voltage reading. Make sure you have a good reason. Connect the red wire from the voltmeter to battery positive (B +) and the black wire to each ground. Once again, you should see the battery voltage every time you plug it in. If not, troubleshoot 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. Other manufacturers show CAN C- at about 5V and an oscillating key with the engine off. Check your manufacturer's specifications.

Then check the other two communication circuits. Locate CAN B+ (or MSCAN + circuit) and CAN B- (or MSCAN - circuit). With the black wire of the voltmeter connected to a good ground, connect the red wire to CAN B+. With the key on and the engine off, you should see a voltage of about 0.5 volts with little fluctuation. Then connect the red lead of a voltmeter to the CAN B circuit. You should see about 4.4 volts with slight fluctuations.

If all tests pass and communication is still not possible, or you were unable to reset DTC U0147, the only thing to do is to seek help from a trained automotive diagnostician as this will indicate a faulty GATEWAY module. Most of these GATEWAY modules must be programmed or calibrated for the vehicle in order to be properly installed.

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