U0112 Lost communication with battery energy control module B
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U0112 Lost communication with battery energy control module B
OBD-II DTC Datasheet
Lost Communication With Battery Power Control Module "B"
What does this mean?
This is a generic communications DTC that applies to most makes and models of vehicles, including but not limited to Toyota, Ford, Chevrolet, Hyundai, and Honda. This code means that the “B” Battery Energy Management Module BECM 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 BECM detects how hot or cold the batteries get and modifies the cooling and heating systems to ensure the batteries don't overheat, get too cold, or even freeze. They do this by turning on or off coolant pumps and fans to cool them, which can lead to heat build-up.
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 U0112 engine code may include:
- Malfunction Indicator Light (MIL) is on
- Hybrid Warning Indicator On
- The car cannot start or run
- The car can run, but on a gasoline engine, only if the hybrid
reasons
Usually the reason for installing this code is:
- Loss of power or ground on "B" BECM - the most common
- 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 or battery / hybrid related, diagnose them first. Misdiagnosis is known to occur if you diagnose the U0112 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 U0112, try contacting the BECM. If you can access the codes from the BECM, then code U0112 is either intermittent or a memory code. If the BECM module cannot be contacted, then code U0112 that other modules set is active and the problem already exists.
The most common failure is a loss of power or ground.
Before going any further, give a caveat: This is a high voltage system! If the warnings are not heeded and / or the manufacturer's protective and diagnostic measures are not followed, damage to the vehicle is VERY likely and could result in injury / personal injury for you. If you are not sure about any stage of the diagnostics, it is strongly recommended that you leave the diagnostics of this code in this system to someone who has been trained in it.
Check all fuses supplying BECM “B” on this vehicle. Check all grounds for the BECM. 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 all modules that set the code in memory and see if U0112 returns or you can contact the BECM. If no code is returned or communication with the BECM is restored, the problem is most likely a fuse / connection issue.
If the code returns, look for the CAN bus connections on your specific vehicle, especially the BECM connector.
DISCONNECT THE HIGH VOLTAGE SYSTEM, FOLLOWING ALL THE PRODUCER'S PRECAUTIONS AND PROCEDURES,
Then, disconnect the negative battery cable before disconnecting the connector on the BECM. 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. Reconnect all connectors. Clear all codes.
If communication is still not possible or you were unable to reset DTC U0112, the only thing to do is to seek the assistance of a qualified automotive diagnostician as this may indicate a faulty BECM module or possible wiring problems with the CAN bus communication system . For proper installation, BECMs must be programmed or calibrated for the vehicle.
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NOTE. This information is provided for informational purposes only. It is not intended to be used as a repair recommendation and we are not responsible for any action you take on any vehicle. All information on this site is protected by copyright.
