Sevcon Troubleshooting
Page 11
Electrical Troubleshooting
Test 5. CONTACTOR COIL FAULT
Disconnect the 12-pin logic card connector from the Sevcon power unit.
Turn the key switch ON and perform the following tests:
TEST 5.1:
Check the voltage on the positive coil terminal of the ISO solenoid
(violet wire).
If the voltage is within approximately 1-volt of the battery
voltage, then skip ahead to test #5.2.
If the voltage is not within approximately 1-volt of the
battery voltage, then check the diode in the positive wire
to the ISO solenoid.
Stop trouble shooting here and repair the problem. When
the repair is completed, completely retest the vehicle before
lowering the drive wheels to the ground.
TEST 5.2:
Check the voltage on the negative coil terminal of the contactor
coil.
If the voltage is not within 1-volt of battery voltage, then
the contactor is bad and must be replaced.
NOTE: An open contactor coil should be accompanied by a 4-flash
code from the logic LED.
If the voltage is within 1-volt, then one of the four
following faults may have occurred:
Broken Wire: Check the wire from pin #8 in the 12-
Stop, do not continue. Reaching this point
indicates a failure in the Sevcon power unit
or an error was made during testing. Confirm
all previous tests were performed correctly
before replacing the Sevcon power unit.
STOP
pin logic card connector to the contactor coil negative terminal for open circuits.
Welded Solenoid Contacts: Test the solenoid for welded contact tips. There are two methods
for checking the contacts:
1. Disconnect the batteries and test the continuity across the contacts. If there is
continuity then the contact tips are welded.
2. With the key switch OFF, check the voltage at the B+ terminal on the Sevcon control
(see illustration on following page). If the voltage at the B+ terminal is at full battery
voltage then the contact tips are welded.
NOTE: Welded tips should be accompanied by a 4-flash code from the logic LED.
Shorted Solenoid Coil: Disconnect the logic card connector and measure the resistance
across the solenoid coil. Depending on the solenoid or contactor you vehicle is equipped
with, the resistance should be 25 ohms or higher (nominal). A reading less than 25 ohms
may indicate a shorted coil.
The control logic may have failed.
Summary of Contents for B0-254-48
Page 2: ......
Page 18: ...TAYLOR DUNN...
Page 74: ...Maintenance Service and Repair Steering Page 22 Exploded View of Steering Gear...
Page 100: ...TAYLOR DUNN...
Page 136: ...TAYLOR DUNN...
Page 142: ...TAYLOR DUNN...
Page 154: ...TAYLOR DUNN...
Page 157: ...Sevcon Troubleshooting Page 3 Electrical Troubleshooting Identifying Your Controller...
Page 176: ...TAYLOR DUNN...
Page 194: ...Illustrated Parts Parts Page 2 Steering Knuckle...
Page 196: ...Illustrated Parts Parts Page 4 Front Brakes Brake body 9 above...
Page 198: ...Illustrated Parts Parts Page 6 Steering Linkage...
Page 206: ...Illustrated Parts Parts Page 14 Transmission Gear Case...
Page 210: ...Illustrated Parts Parts Page 18 Rear Brakes Brake body 8 above...
Page 212: ...Illustrated Parts Parts Page 20 Master Cylinder Brake linkage Linkage at the brake caliper...
Page 214: ...Illustrated Parts Parts Page 22 Brake Lines...
Page 216: ...Illustrated Parts Parts Page 24 Rear Suspension View from rear...
Page 218: ...Illustrated Parts Parts Page 26 Motor Rear Motor Mount...
Page 220: ...Illustrated Parts Parts Page 28 Instrument Panel dash...
Page 232: ...TAYLOR DUNN...
Page 233: ...APPENDIX A Special Tools...
Page 242: ...Model B 1 00...
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