Comanche 4WD L6-242 4.0L VIN L FI (1990)
Fuel Injector: Testing and Inspection
Fuel Injector Electrical Circuit Diagnosis
NOTE: The fuel system wiring diagrams should be used in conjunction with the following test to correctly diagnose the problem.
1.
Turn the ignition switch to the CRANK position.
2.
Using a logic probe or a noid light, probe the injector electrical connectors and check that the injectors are receiving signals from the ECU.
3.
If there is no signal at any of the injector electrical connectors, disconnect the 24-Way and 32-Way ECU electrical connectors and the injector
electrical connectors. Connect an ohmmeter across the BK wire of each injector connector to ground, and check for continuity. If there is no
continuity, fix open in wire. If there is continuity, go to step 4.
4.
Connect an ohmmeter to each injector connector as follows:
a.
Connect the ohmmeter across the BR wire of injector #6 connector and terminal A2 of the ECU connector, and check for continuity. If there
is no continuity, repair the open in the wire. If there is continuity, the problem is computer related.
b.
Connect the ohmmeter across the WT wire of injector #5 connector and terminal B2 of the ECU connector, and check for continuity. If there
is no continuity, repair the open in the wire. If there is continuity, the problem is computer related.
c.
Connect the ohmmeter across the YL wire of injector #4 connector and terminal A4 of the ECU connector, and check for continuity. If there
is no continuity, repair the open in the wire. If there is continuity, the problem is computer related.
d.
Connect the ohmmeter across the TN wire of the injector #3 connector and terminal A1 of the ECU connector, and check for continuity. If
there is no continuity, repair the open in the wire. If there is continuity, the problem is computer related.
e.
Connect the ohmmeter across the LG wire of injector #2 connector and terminal A3 of the ECU connector, and check for continuity. If there
is no continuity, repair the open in the wire. If there is continuity, the problem is computer related.
f.
Connect the ohmmeter across the LB wire of injector #1 connector and terminal B1 of the ECU connector, and check for continuity. If there
is no continuity, repair the open in the wire. If there is continuity, the problem is computer related.