Test FD: Fuel Gauge Does Not Display "E" When Tank Is Empty; "Co" Is Displayed; Display Blanks Out Fuel Tank Symbol; Top 2 & Bottom 2 Segment Bars Are Illuminated

NOTE: At time of service, check TSB 90-7-11 - EIC Shows Fuel Increases Or Displays "CO" Intermittently On Vehicles Built From 6/1/89 To 1/15/90.

Check Fuel Tank Sending Unit Wiring At Sending Unit

Disconnect negative battery cable. Lower fuel tank to gain access to fuel tank sending unit connector. Unplug fuel tank sending unit connector. Place jumper wire between variable resistance terminal and ground terminal of harness. Reconnect negative battery cable. Turn ignition switch from OFF to RUN position. Monitor fuel display and check for "CO" or "CS" is indicated (it may take several minutes for fuel display to respond). If "CO" is displayed, go to step 3 . If "CS" is displayed, remove jumper wire, and go to next step.

Check Sending Unit

Turn ignition switch to OFF position. Using DVOM, measure resistance across fuel tank sending unit terminals. If resistance is not 9-161 ohms, replace fuel tank sending unit. If resistance is 9-161 ohms, inspect fuel tank sending unit harness connector terminals for flash or loose fit. Repair as necessary.

Check Fuel Tank Sending Unit Wiring At Cluster

Remove Electronic Instrument Cluster (EIC), and insulate wiring harness and connectors from any possibly shorting. See ELECTRONIC INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Place jumper wire between fuel tank sending unit harness connector variable resistance terminal and ground terminal. Using DVOM, check for continuity between EIC connector "B" terminals No. 6 circuit 29 (Yellow/White wire) and No. 8 circuit 359 (Black/White wire). If continuity exists, go to next step. If continuity does not exist, repair open in fuel tank sending unit wiring circuit.

Check For Open At Fuel Tank Sending Unit

Remove jumper wire, and install 3-watt or larger resister of 90-130 ohms between variable resistance terminal and ground terminal of fuel tank sending unit harness connector. Reconnect EIC, and start engine. Disregard fuel gauge level. If "CO" is displayed, replace EIC. See ELECTRONIC INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. If "CO" is not displayed, replace fuel tank sending unit.