Isuzu 1999 RODEO Workshop Manual page 1591

6E2–348
RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
9. To avoid backprobing the VSS and possibly
damaging a seal or terminal, the VSS output can be
tested at the point where the transmission harness
connected to the engine harness. The green 16-way
connector is adjacent to a blue 16-way connector,
and it can be easily accessed by removing the air
cleaner assembly. The green 16-way connector is
separated, and battery voltage is applied to the VSS
through the yellow wire at one corner of the
connector. The VSS output can be monitored with a
DVM connected to the blue wire with a black tracer.
The two wires are next to each other in the 16-way
connector . The test connections are made on the
transmission side of the connector, the side that is
not clipped to the body sheetmetal.
Step
1 Was the "On-Board Diagnostic (OBD) System Check"
performed?
2 Does the speedometer work?
3 1. Disconnect the VSS connector.
2. Ignition "ON."
3. Using a test light to battery +, probe the connector
ground wire.
Did the light illuminate?
4 Repair the sensor ground.
Is the action complete?
5 1. Ignition "ON," sensor disconnected.
2. Using a DVM, measure at the VSS connector
between ground and voltage supply.
Was the measurement near the specified value?
6 Repair the open or short to ground which may have
blown the meter fuse.
Is the action complete?
7 1. Ignition "ON," VSS disconnected.
2. Using a DVM, measure at the VSS connector
between ground and the blue/black wire from the
speedometer.
Was the measurement near the specified value?
8 Check for an open or short circuit between the
speedometer and the VSS.
Was an open or short circuit located?
9 Replace the speedometer.
Is the action complete?
DTC P0502 –VSS Circuit Low Input
Action
14. The speedometer-to-PCM VSS signal wire is
spliced to a wire leading to the cruise control
module. If a short to ground or voltage is found
between the PCM and speedometer, it could be
located between the splice and the cruise control
module.
Value(s)
— Go to Step 2
Go to Step 10
—
Go to Step 5
—
— Verify repair
Battery
Go to Step 7
voltage
— Verify repair
7.5-8 V Go to Step 9
— Verify repair
— Verify repair
Yes No
Go to OBD
System
Check
Go to Step 3
Go to Step 4
—
Go to Step 6
—
Go to Step 8
Go to Step 9
—