If the voltage is not present, it could indicate an open or short to ground. If the voltage is present but not toggling, it could indicate a short to power. If using the EL-50772 Insulation Multimeter set to “peak” min/max, the voltages will be approximately 12 volts max and 1 volt min. At the slave device, inspect for the toggling voltage from the master control module on the LIN bus. Check the output voltage from the master control module: With the master control module connected, disconnect the slave device and turn on the ignition.Testing/monitoring the voltage of the LIN bus can help determine what type of failure may have occurred.Use the proper terminal test probes to inspect for these types of failures. The LIN bus is a single wire and many faults are basic failures, such as opens, high resistance, shorts to ground/power, poor terminal drag, or connectors not fully seated.This can help in narrowing down the area of concern.
#Gm ecm reprogramming windows#
Looking at the schematic, if the customer’s concern was that the rear wiper was not operating, check to see if the rear power windows operate. If a LIN bus has more than one slave device, check to see if the other devices are working.9) Always follow the appropriate diagnostics in the Service Information. The LIN bus schematic is used as an example in some of the tips. Here are a few diagnostic tips for the LIN bus circuit. As result, the BCM will turn on the interior dome lights and start waking up other modules. The message wakes up the BCM and it communicates to the vehicle that the driver’s door is open. When the driver’s door is opened, the ajar switch closes, signaling to the driver’s window motor to send a LIN message to the BCM. The driver’s window motor has a LIN bus to the BCM. For example, the door ajar switch is hard-wired to the driver’s window motor. However, in some cases, the slave device will wake up the master control module. If the slave device does not wake up, the master control module will set a DTC for that device and will continue to try and wake up the slave device, which can be seen by the toggling voltage on the LIN bus. In most cases, when the ignition is turned on, the master control module will wake up the slave device(s) via the LIN bus. When a LIN bus is at rest or not communicating, it will read approximately 11–12 volts. Install the EL-50313 Midtronics GR8 Battery Tester/Charger or equivalent on the vehicle while diagnosing a LIN bus to avoid a false reading. 8) Because the LIN bus voltage ranges between 12 volts and 1 volt, it’s important to have proper battery voltage while performing diagnostics.
#Gm ecm reprogramming serial#
If serial data communication is lost between any of the LIN devices on the LIN bus network, the master control module will set a no communication code against the non-communicating LIN device.Įach component on the LIN bus (master and any slave devices) will send out approximately 11-12 volts and then toggle that voltage low when communicating. The scan tool will communicate with the master control module of the LIN bus in order to command outputs or read parameters from the slave/smart device(s). LIN buses are not wired to the DLC, so the scan tool does not communicate directly on a LIN bus. The LIN bus is relatively simple and exchanges data at a slower rate than other GMLAN buses. The LIN bus consists of a single wire and is used to exchange information between one master control module (such as an ECM, BCM, etc.) and one or more slave/smart device(s), such as switches, sensors, motors, etc. Smart motors, switches, and sensors that use Local Interconnect Network (LIN) buses can be found on many 2014-2020 GM passenger cars and trucks.
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