Chevrolet Volt Water Heater

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It is 5kW Eberspächer coolant heater that works on 400Vdc. It is found in Chevrolet Volt gen1 and Opel Ampera cars as well as others. This model is SW CAN controlled.

3 pin LV connector has GND, SW CAN and ENABLE pins in that order.

Temperature sensor is 3.2Kohm at 21degC. It is NTC type.

This info from EVTV Forum: The Eberspacher CAN version of their PTC liquid heater used in the Chevrolet Volt will work when used with a 33.33Kb SWCAN. The data below is what we have found to be the minimum required to turn on and operate this heater. This capture will operate the heater at approximately 33% of full power. To command higher power, increase the value of message 0x10720099 byte 1 (it begins with byte 0) which is 3E below. We saw full power heat when 85 was used as the value for byte 1 and that value will vary based upon inlet temperature. The data below contains an entry for “Bus” and that refers to which CAN Bus of the 2 Buses on the CANDue recorded the original event.














ID Extended Bus LEN Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7
0x100 False 1 0 0 0 0 0 0 0 0 0

Michael Neuweiler has published this wiring on his blog.

Connecting using CAN board and Canalyst II does nothing since it is not normal CAN interface. This heater is supposed to work only with SW CAN transciever. Transciever should output a wake up signal for everything to work. One such SW transciever is NCV7356.