GENERAL SYSTEM DIAGNOSTICS
SERVICE MANUAL NUMBER 23
Page 5E-102
90-861326--1 MARCH 1999
Discrete Input Circuit Check - Non-Scan 7.4L MPI Only (5 of 5)
TESTING FOR OPEN CIRCUITS
STEP
ACTION
VALUE
YES
NO
PROCEED TO
1
1. Disconnect PUR wire from oil pressure
switch.
2. Disconnect TAN/WHT wire from gear
lube monitor.
3. Disconnect BLU/TAN wire from transmis-
sion temperature switch (if equipped).
4. Key “ON”, engine “OFF”.
5. One at a time, touch each wire to ground
(–) that was disconnected.
Does audio warning buzzer sound when
grounding PUR wire?
Step 3
Step 2
Does audio warning buzzer sound when
grounding TAN/WHT wire?
Step 3
Step 2
Does audio warning buzzer sound when
grounding BLU/TAN wire?
Step 3
Step 2
2
1. Key “OFF”.
2. Disconnect ECM J1 connector.
3. Check for continuity between all wires
disconnected in “Step 1” and terminal J1-4
(J1-6 on Later Models).
Is there continuity on PUR wire?
0 Ohms
Step 3
Step 4
Is there continuity on TAN/WHT wire?
0 Ohms
Step 3
Step 4
Is there continuity on BLU/TAN wire?
0 Ohms
Step 3
Step 4
3
Circuit(s) is not open.
–
–
4
Repair open circuit.
–
–
NOTE: The ECM should only be replaced after all switches and circuits have been tested
and found to be functioning properly.
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