Subaru 602 - Ground Short of CAN High Wire

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June 2013
Electrical Systems Operation & Diagnosis Module (602)
Resistance checks should show continuity or very low resistance from the DLC to the CAN high
wire and CAN low wire. Check the CAN high wire first. Check from the DLC to the affected modules
electrical connector. Record the value and then check the CAN low wire the same way.
Voltage checks at the affected control module electrical connector should show the same value
monitored at the DLC.
If either resistance or voltage checks indicate that an open circuit exists then the next step is to
locate the CAN Joint Connector that connects the affected control module to the CAN.
Check the CAN Joint Connector for resistance or voltage to the affected module’s CAN wires.
Once the open circuit is located, repair the circuit and recheck the entire CAN operation.
Ground Short of CAN High Wire
When a short to ground occurs on the CAN high wire, the voltage difference between the CAN
high wire and CAN low wire is not high enough for any control module to receive and understand
the data being sent. The voltage level of the CAN high wire must always be higher than the CAN
low wire or communications on the CAN stop.
Main bus
ELECTRIC
POWER
STEERING CM
COMBINATION
METER
BODY
INTEGRATED
UNIT
STEERING
ANGLE
SENSOR
VDC CM
120Ω120Ω
TCM
DATA LINK
CONNECTOR
A/C CM
ELECTRONIC
PARKING
BRAKE CM
ECM
CAN Low
CAN High Wire
RT = ____________________
1 state 0 state
Voltage CAN High _____________ _______________
Voltage CAN Low _____________ _______________
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