Vss Pin-Point Diagnostics (Allison Transmissions) - Navistar International DT 466 Diagnostic/Troubleshooting Manual

7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
VSS Pin-Point Diagnostics (Allison
Transmissions)
Figure 510 VSS circuit diagram (Allison transmissions)
The VSS circuit requires the use of vehicle circuit diagrams. See truck Chassis Electrical Circuit Diagram
Manual for circuit numbers, connector and fuse locations.
Connector Voltage Checks (Disconnect harness from sensor. Inspect for bent pins or corrosion. Turn the
ignition switch to ON.)
Test Point
ECU transmission Pin
to gnd
WARNING: To avoid serious personal injury, possible death, or damage to the engine or vehicle,
always disconnect main negative battery cable first. Always connect the main negative battery cable
last.
Resistance Checks to Chassis Ground with Breakout Box (Turn the ignition switch to OFF. Connect
breakout box X4 only to chassis harness. Disconnect chassis connector 9260
cable. Use disconnected negative battery cable for ground test point.)
X4–10 to gnd cable
Harness Resistance Checks (Check with breakout box connected to engine harness only. Check from
ECM to sensor harness connector.)
X4–10 to ECU
transmission Pin
Note: If circuit checks are within specification and condition remains, see transmission manual for sensor
inspection and adjustment.
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Spec
2 V to 3 V
> 1 kΩ
< 5 Ω
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
Comment
ECM pull up voltage when sensor disconnected. If no
voltage present, check for open or short to ground.
If < 1 kΩ, check for short to ground.
If > 5 Ω, check for open circuit.
EGES-270-1
1
. Disconnect negative battery
549