Improper Fuel Data Display

Fig. 37 Improper fuel data display diagnostic chart (Part 1 of 3):

Fig. 37 Improper fuel data display diagnostic chart (Part 2 of 3):

Fig. 37 Improper fuel data display diagnostic chart (Part 3 of 3):

1. Turn ignition off for 10 seconds, then back on, and enter diagnostics. If ``-1.8.8'' is displayed, proceed to step 2. If ``-1.8.8'' is not displayed, refer to ``Diagnostic Display Problems.''
2. Perform ``switch tests.'' If Codes .7.8 and .7.9 pass, proceed to step 3. If codes do not pass, refer to appropriate diagnostic procedure.
3. If all digits and segments of panel display properly and the ``instant'' and ``average'' lights function normally, proceed to step 4. If any malfunction is noted, refer to Fig. 37 for diagnosis.
4. Depress ``fuel used/range'' button (``fuel used'' button on models with digital cluster) while ``instant MPG'' is displayed. If ``fuel used'' indicator lights, proceed to step 5 or 6. If lamp does not light, replace fuel data panel.
5. On models equipped with mechanical speedometer, proceed as follows:
a. Depress ``fuel used/range'' button while ``fuel used'' is displayed.
b. If ``range'' displays properly, the system is functioning normally.
c. If ``L'' is displayed continuously, and the fuel gauge is operating properly, check circuit 30 for an open between fuel gauge and ECM. If circuit is satisfactory, fault is in ECM or ECM connector. Repair or replace as necessary.
d. If depressing ``fuel used/range'' button while ``fuel used'' is displayed has no effect on ``range'' display, the wrong PROM units are installed. Replace PROMS with correct unit for application.
6. On models equipped with digital speedometer, proceed as follows:
a. Depress ``fuel used'' button while ``fuel used'' is displayed.
b. If depressing ``fuel used'' button has no effect on display, the system is functioning normally.
c. If ``L'' is displayed, the wrong PROM units are displayed. Replace PROMS with correct units for application.