What does it mean?
SPECIAL NOTES ON OBD II CODE B1342 Due to the general nature and the widely different applications of code B1342 between manufacturers, the information in this guide is presented for general informational purposes only. As such, the information presented here should NOT be seen as exhaustive and/or definitive with regard to any diagnostic procedure that involves this code.
Always consult the manual for the application being worked on for accurate and relevant information on code B1342 as it applies to that particular application. END OF SPECIAL NOTES. OBD II fault code B1342 is most commonly defined as “ECU (Electronic Control Unit) has failed”, or sometimes as “GEM (Generic Control Module) has failed”.
Note that there are other definitions with slightly different wording but regardless of the actual wording of the definition, this code refers to the failure of one or more control modules, as opposed to a general failure of, or in, the CAN Bus (Controller Area Network) wiring.
On some applications, many functions that do not affect engine/fuel/transmission management are performed/monitored/executed by the PCM, while on others, a generic electronic control module oversees/manages/controls all functions that do not involve engine and fuel management.
While the end result, which is the management of all electronic and control functions is the same in all cases, the practical aspects of diagnosing and repairing code B1342 depends entirely on whether any given application is fitted with a generic control module or a centrally located PCM.
Control modules that are covered by code B1342 vary between applications, but the most common modules include the following- ABS Air bags Ignition Electronic power steering Note that the above list includes only modules that affect safety and driveability. Some applications can have as many as 18 or more modules that control anything from power window operation to seat adjustment to navigation and infotainment systems.
The actual number of control modules on any given application depends on the make and model, but code B1342 generally applies to all body control issues on all applications. The image below shows the typical systems and/or controllers that are covered by code B1342.
Symptoms
- Several unrelated systems misbehave at the same time: lighting, wipers, central locking, windows, chimes
- Multiple warning lamps lit and many communication codes stored across the vehicle
- Scan tool cannot communicate with the module, or communicates only intermittently
- The vehicle may not start, or the immobiliser may refuse to release
- Battery drains because the module never goes to sleep
Likely causes
- Internal failure of the body / general electronic control module, very often after water damage
- Water entering the cabin through a blocked plenum drain, sunroof drain or windscreen seal and reaching the module
- Low or unstable supply voltage, or damage from a reverse-polarity jump start
- Corroded or high-resistance module ground
- Corroded, green or pushed-back pins at the module connectors
- Interrupted or corrupted software update leaving the module unusable
- Voltage spikes from welding on the vehicle without disconnecting the modules
How to fix it
- Scan every module and record all codes before clearing anything, the pattern shows whether the module or the bus is at fault
- Check for water damage where the module is mounted, looking for damp carpet and water staining
- Measure supply voltage and ground at the module connector and voltage-drop test the ground path
- Test the battery and charging system, because low voltage produces exactly these symptoms
- Inspect the module connectors for corroded, green or pushed-back pins
- Try a software update or reflash where the manufacturer supports it before condemning the hardware
- Replace the module only after wiring, power, ground and bus are all proven good, then program and configure it to the vehicle and clear all codes