CAN BUS MODULES

Gen IV ECMs introduced CAN bus communication; a robust serial data broadcast bus where each module sends and receives frames of data related to engine and transmission operation. The bus operates between a recessive state (CAN wire voltages near 2.5V - a logic of 1) and a dominant state (CAN wire voltage differential of nominal 2V - a logic of 0).

COMING SOON! (DEVELOPMENT PROGRAM OPPORTUNITY NOW THROUGH EARLY 2024)
We are currently developing CAN bus modules that will communicate with all E40, E38, E67, and E78 ECMs to add stand-alone lost features such as cruise control, A/C request, starter relay, tap shift, tow/haul, backup lamps, and neutral safety. If you would like to participate in our development program (and receive a discount on our upcoming CAN bus modules), please send us an email at help@lswiring.com. Be sure to include ECM type and the year/model/engine of the base GM calibration you are using.

Twisted Pair CAN High and CAN Low Wires
You will easily identify the CAN bus wires within your engine harness by looking for the twisted pair wires that can be found at pins 6 and 14 of the OBD-II diagnostic connector. LSWiring Gen IV LS Engine Wire Harnesses feature a CAN Bus Splice Saver Connector (here) for easy expansion of CAN modules on the bus.

120Ω Termination Resistors
Each end of the CAN bus must be terminated with a 120Ω resistor, wired in parallel, to accomplish a bus resistance of 60Ω. All Gen IV ECMs are internally wired with a 120Ω resistor. To complete bus termination, your engine harness must have a second termination resistor (here). Failure to establish a bus resistance of 60Ω may result in incorrect voltage differential and data reflections that will corrupt frame data on the bus. Measure your CAN bus resistance, ignition key off, with a digital multimeter across OBD-II DLC pins 6 and 14. If your bus resistance measures 120Ω, then your wire harness only contains termination through the ECM and you should add an additional termination resistor.