Jeep 1996 Grand Cherokee Service Manual - page 1091
(26) Verify that fuel pump/gauge sender unit wire
connector is firmly connected to harness connector.
(27) Inspect fuel hoses at fuel pump/gauge sender
unit for cracks or leaks.
(28) Inspect transmission torque convertor housing
(automatic transmission) or clutch housing (manual
transmission) for damage to timing ring on drive
plate/flywheel.
(29) Verify that battery cable and solenoid feed
wire connections to the starter solenoid are tight and
clean. Inspect for chaffed wires or wires rubbing up
against other components.
ASD AND FUEL PUMP RELAYS
The following description of operation and
tests apply only to the Automatic Shutdown
(ASD) and fuel pump relays. The terminals on the
bottom of each relay are numbered (Fig. 43).
OPERATION
• Terminal number 30 is connected to battery volt-
age. For both the ASD and fuel pump relays, termi-
nal 30 is connected to battery voltage at all times.
• The PCM grounds the coil side of the relay
through terminal number 85.
• Terminal number 86 supplies voltage to the coil
side of the relay.
• When the PCM de-energizes the ASD and fuel
pump relays, terminal number 87A connects to termi-
nal 30. This is the Off position. In the off position,
voltage is not supplied to the rest of the circuit. Ter-
minal 87A is the center terminal on the relay.
• When the PCM energizes the ASD and fuel
pump relays, terminal 87 connects to terminal 30.
This is the On position. Terminal 87 supplies voltage
to the rest of the circuit.
TESTING
The following procedure applies to the ASD and
fuel pump relays.
(1) Remove relay from connector before testing.
(2) With the relay removed from the vehicle, use
an ohmmeter to check the resistance between termi-
nals 85 and 86. The resistance should be between 75
65 ohms.
(3) Connect the ohmmeter between terminals 30
and 87A. The ohmmeter should show continuity
between terminals 30 and 87A.
(4) Connect the ohmmeter between terminals 87
and 30. The ohmmeter should not show continuity at
this time.
(5) Connect one end of a jumper wire (16 gauge or
smaller) to relay terminal 85. Connect the other end
of the jumper wire to the ground side of a 12 volt
power source.
(6) Connect one end of another jumper wire (16
gauge or smaller) to the power side of the 12 volt
power source. Do not attach the other end of the
jumper wire to the relay at this time.
WARNING:
DO NOT ALLOW OHMMETER TO CON-
TACT TERMINALS 85 OR 86 DURING THIS TEST.
(7) Attach the other end of the jumper wire to
relay terminal 86. This activates the relay. The ohm-
meter should now show continuity between relay ter-
minals 87 and 30. The ohmmeter should not show
continuity between relay terminals 87A and 30.
(8) Disconnect jumper wires.
(9) Replace the relay if it did not pass the continu-
ity and resistance tests. If the relay passed the tests,
it operates properly. Check the remainder of the ASD
and fuel pump relay circuits. Refer to group 8W, Wir-
ing Diagrams.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
TEST—5.2L ENGINES
To perform a complete test of MAP sensor (Fig. 44)
and its circuitry, refer to DRB scan tool and appro-
priate Powertrain Diagnostics Procedures manual. To
test the MAP sensor only, refer to the following:
(1)
Inspect the rubber L-shaped fitting from the
MAP sensor to the throttle body (Fig. 45). Repair as
necessary.
CAUTION:
When testing the MAP sensor, be sure
that the harness wires are not damaged by the test
meter probes.
(2) Test the MAP sensor output voltage at the
MAP sensor connector between terminals A and B
(Fig. 46). With the ignition switch ON and the engine
OFF, output voltage should be 4-to-5 volts. The volt-
age should drop to 1.5-to-2.1 volts with a hot, neutral
idle speed condition.
Fig. 43 ASD and Fuel Pump Relay Terminals
14 - 46
FUEL SYSTEM
ZJ
DIAGNOSIS AND TESTING (Continued)