CAUSE B - CAN HI OR CAN LO OPEN CIRCUIT
PROCEDURE OR ACTION:
1. Ensure truck power is OFF.
2. Disconnect EPR, ECM, and engine to main harness connector that carries the CAN circuit.
3. Change DMM to ohms scale. Verify DMM zero reading.
4. Ensure connector pins are fully seated in their respective housing.
5. At the EPR connector and ECM connector, measure resistance between the two pins on the Can Hi circuit.
Is resistance less than 0.5 ohms?
YES: Go to Step 6.
NO: CAN Hi wire is open circuit. Locate and repair/replace open wire/connection. See Wire Harness Repair
2200SRM1128.
6. At the EPR connector and ECM connector, measure resistance between the two pins on the Can Lo circuit.
Is resistance less than 0.5 ohms?
YES: Go to Cause C.
NO: CAN Lo wire is open circuit. Locate and repair/replace open wire/connection. See Wire Harness Repair
2200SRM1128.