Vanguard 25E300, Repair Manual

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Preliminary Instructions
Prior to starting any diagnostic, repair or maintenance
operation. Make sure you are familiar with ALL safety
warnings and procedures as outlined in SECTION 1 -
SAFETY AND GENERAL INFORMATION - General Safety
Messages .
ALWAYS wear safety glasses and gloves while performing
any diagnostic, maintenance or repair operation.
CAN BUS Troubleshooting
Troubleshooting DTCs may not always get to the real source of the problem, as there can be instances where the problem
originates with the CAN bus. Bad connections can result in faulty communications with the ECM resulting in a faulty diagnosis.
Check Voltages
Step Action
1 1. Turn Ignition OFF.
2. Back probe CAN Hi terminal C (Yellow wire) at the DLC.
3. Connect terminal C back probe to red meter test lead on DVOM.
4. Connect black meter test lead on DVOM to ground.
5. Turn Ignition ON, Engine OFF.
6. Compare voltage to table below.
2 1. Turn Ignition OFF.
2. Back probe CAN Lo terminal D (Green wire) at the DLC.
3. Connect terminal D back probe to red meter test lead on DVOM.
4. Connect black meter test lead on DVOM to ground.
5. Turn Ignition ON, Engine OFF.
6. Compare voltage to table below.
DLC
Can Bus
Circuits
Sleep Idle
(Recessive)
KOEO
Active Bus CAN Lo Short
to Ground
CAN Hi Short
to Ground
CAN Lo Short
to Power
CAN Hi Short
to Power
CAN Hi Short
to CAN Lo
CAN Lo (-) 0 VDC 2.5 VDC 1.5 VDC
– 2.5 VDC
0 VDC 0-0.5 VDC 5-12 VDC Below
0.75 VDC
2.45 VDC
CAN Hi (+) 0 VDC 2.5 VDC 2.5 VDC
– 3.5 VDC
0-0.5 VDC 0 V Below
0.75 VDC
5-12 VDC 2.45 VDC
Resistance Test 120 Ohms: Between both CAN HI and LO
20 vanguardpower.com
Not for
Reproduction