Body CAN, powertrain CAN, and suspension CAN oscilloscope measurement
In order to obtain a clear idea of whether the CAN bus is functioning properly, you must be able to observe activity on the bus. You do not need to analyze the individual bits; you simply need to observe whether or not the CAN bus is working. The oscilloscope test can state that, "the CAN bus is probably operating without faults".
When you measure the voltage between the CAN Low line (or CAN High line) and the ground, you receive a rectangle-like signal in the following voltage ranges:
- Body CAN:
CAN Low to ground: U min = 1 volts and U max = 5 volts
CAN High to ground: U min = 0 volts and U max = 4 volts
These values are approximate values and can vary by a few hundred mV depending on the bus load.
Oscilloscope settings for the measurement at the K-CAN:
| CH1: | Probe tip 1, range 2 V/div; DC coupling |
| CH2: | Probe tip 2, Range 2 V/div; DC coupling |
| Time: | 50 μs/div |
When you measure the voltage between the CAN Low line (or CAN High line) and the ground, you receive a rectangle-like signal in the following voltage ranges:
- PT-CAN and F-CAN
CAN Low to ground: U min = 1.5 volts and U max = 2.5 volts
CAN High to ground: U min = 2.5 volts and U max = 3.5 volts
These values are approximate values and can vary by a few hundred mV depending on the bus load.
Oscilloscope settings for the measurement at the PT-CAN (or F-CAN):
| CH1: | Test probe 1, range 1 V/div; DC coupling |
| CH2: | Test probe 2, range 1 V/div; DC coupling |
| Time: | 10 μs/div |