Pontiac Fiero 1988 Service Manual page 1005

V E H I C L E S P E E D S E N S O R • 1
(Continued from previous page)
A: VEHICLE SPEED SENSOR BUFFER
TEST (TABLE 2)
Measure: A C VOLTAGE
At: INSTRUMENT CLUSTER CONNECTOR
C1 (Connected)
Conditions:
• Ignition Switch: RUN
• Gear Selector: NEUTRAL
• Raise car off the ground and turn drive
wheels by hand while making
measurement
Measure
Between
S(YEL)&R
(PPL/WHT)
Correct
Voltage
Varying from
1 to 5 Volts
AC
For Diagnosis
Seel
If the voltage is correct, check the printed
circuit for flaws and cracks. If OK, replace
Instrument Cluster (see Section 8C).
Check/repair the YEL (400) and PPL/
WHT (401) wires (see schematic). Replace
the Vehicle Speed Sensor if both wires are
OK and connector C203 is correctly
mated (see Section 8C).
B: VEHICLE SPEED SENSOR BUFFER
OUTPUT TEST (TABLE 1) V6 VIN 9
ONLY
Measure: VOLTAGE
m: INSTRUMENT CLUSTER CONNECTOR
C1 (Disconnected)
Conditions:
• Ignition Switch: RUN
• Connector C 2 4 5 : DISCONNECTED
Measure
Between
U (DK GRN/
WHT)&
Ground
Correct
Voltage
Battery
For Diagnosis
Seel
• Connector C245: CONNECTED
© Cruise Control: ON
• Connector C203: DISCONNECTED
U (DK GRN/
WHT) &
Ground
Battery See 2
If all voltages are correct, go to Table 2.
Check the DK GRN/WHT (389) wire and
BRN (437) wire for an open and check that
connector C203 is mated correctly. If all
are good, replace the Electronic Control
Module.
Check the DK GRN/WHT (389) wire for
an open and check that connector C245 is
mated correctly. If both are OK and
Cruise Control diagnostics in Section
8A-34 have been completed, replace
Cruise Control Module.
B: VEHICE SPEED SENSOR BUFFER
OUTPUT TEST (TABLE 1) L4 VIN R
ONLY
Measure: VOLTAGE
At: INSTRUMENT CLUSTER CONNECTOR
C I (Disconnected)
Condition:
• Ignition Switch: RUN
Measure
Between
U (DK GRN/
WHT)&
Ground
Correct
Voltage
Battery
For Diagnosis
Seel
• If the voltage is correct, go to Table 2.
1. Check the DK GRN (389) wires for an
open (see schematic). Check that connec-
tor C203 is mated correctly. If all are
good, replace ECM.
B: VEHICLE SPEED SENSOR BUFFER
OUPUTTEST (TABLE 2)
Measure: VOLTAGE
At: INSTRUMENT CLUSTER CONNECTOR
C I fConnected)
Conditions:
• Ignition Switch: RUN
• Gear Selector: NEUTRAL
• Raise car off the ground and turn the
drive wheels by hand while
making
measurement
Measure
Between
Correct
Voltage
For Diagnosis
U(DK GRN/
WHT)&
Ground
Varying from
less than 1
volt to more
than 4 volts
Seel
(Continued on next page)