Isa Motor Diagnostic Test - Jeep 1987 Wrangler Workshop Manual

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THROTTLE BODY FUEL INJECTION SYSTEM
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1.4L 1986-1987/1.7L/2.46L
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T h e voltage should be close to zero at closed
throttle and greater than 2 volts when off the
closed throttle position.
If no voltage is present in either position, test for
a short circuit to ground in the wire harness or
switch.
A - Ground ( - )
B - Closed throttle switch
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T e s t for an open circuit between terminal 2 5
( E C U connector) and the switch.
If the voltage is always more than 2 volts, test for
an open circuit in the wire h a r n e s s between the
E C U and the switch connector, and between the
switch connector and ground.
R e p a i r or r e p l a c e t h e w i r e h a r n e s s a s
n e c e s s a r y .
ISA Motor Diagnostic Test
W A R N I N G : After testing the operation of the
I S A motor, or if the I S A motor h a s b e e n
replaced, always extend the ISA motor before
starting the engine to prevent the I S A motor from
jamming.
N O T E : T h e following test must be performed
using Exerciser tool E l e . A B . 9 9 .
N O T E : If the ISA motor is to be tested off the
vehicle, the I S A motor shaft must be lightly
preloaded to avoid having the I S A motor jam
during the test. U s e light finger p r e s s u r e to
preload the ISA motor shaft and simulate throttle
return pressure.
R e m o v e the air c l e a n e r a s s e m b l y (Renault
only).
C h e c k to ensure that the rubber boot is correctly
positioned in its groove on the I S A motor shaft.
• if not, correct its position and recheck vehicle
for proper idle s p e e d operation
• if correctly positioned, continue d i a g n o s i s
procedure
O p e n the throttle and attempt to extend and
retract the ISA motor by pulling and pushing
axially (in and out) on the I S A shaft.
C A U T I O N : If the shaft axial movement is more
than 9 . 5 2 5 mm (3/8 in.), do not continue.
R e p l a c e the ISA motor.
B e sure the ignition switch is in the O F F position.
Connect the exerciser clips to the vehicle battery
(red to positive/black to negative).
Disconnect the ISA motor connector.
C o n n e c t the ISA motor exerciser 4-pin c o n -
nector to the ISA motor.
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