Pontiac Fiero 1988 Service Manual page 527

6E2-C1-10 DRIVEABILITY AND EMISSIONS - FUEL INJECTION (TBI)
P/N SWITCH
CONNECTOR
HARNESS CONNECTOR
inn
B I B B l B l E l
FRONT
IIOJ
VIEW
PARK/NEUTRAL
SWITCH
ECM
NEUTRAL START
AND BACK-UP
SWITCH
TRANSAXLE
MOUNTED
— 0 R N / B L K 4 3 4
B I"" 450
W18
5-1-87
CIRCUIT TO GROUND IN
PARK AND NEUTRAL
f
M^\h
12V
— P/N SIGNAL
4-21-87
7 S 3 2 1 6 - 6 E
C H A R T C-1A
PARK/NEUTRAL SWITCH DIAGNOSIS
2.5L "P" SERIES (TBI)
Circuit Description:
The Park/Neutral switch contacts are a part of the neutral start switch and are closed to ground in park or
neutral, and open in drive ranges.
The ECM supplies ignition voltage through a current limiting resistor to CKT 434 and senses a closed
switch, when the voltage on CKT 434 drops to less than one volt.
The ECM uses the P/N signal as one of the inputs to control:
Idle Air Control
VSS Diagnostics
Test Description:
Numbers below refer to circled
3.
Be sure "Scan" indicates drive, even while
numbers on the diagnostic chart. wiggling shifter to test for an intermittent or
1. Checks for a closed switch to ground in park misadjusted switch in drive range,
position. Different makes of "Scan" tools will read
P/N differently. Refer to tool operations manual
for type of display used.
2. Checks for an open switch in drive range.