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June 2013
Electrical Systems Operation & Diagnosis Module (602)
High Speed CAN Voltage Check
Voltage checks from the DLC are possible with the CAN active (Ignition on, Engine off). The
normal voltage readings will vary by year, model, and the amount of data being carried on the
CAN. The CAN high wire and the CAN low wire will always have a different value during normal
circuit operation.
Can High Wire
Checked with an oscilloscope, the pattern of the signals will change from approximately 2.50
volts to 3.60 volts. If you check this value with a voltmeter, the voltage reading will average out to
approximately 2.60 volts.
Can Low Wire
Checked with an oscilloscope, the pattern of the signals change from approximately 2.5 volts to 1.4
volts. If you check this value with a voltmeter, the voltage reading will average out to approximately
2.40 volts.
Note: Any change to the total circuit resistance of the CAN will result in changes to
the volt meter readings for the CAN high and CAN low wire at the same time.
One cannot change without affecting the other.
NOTES:
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