Fuel Gauge Inoperative
- Fuel level is displayed as a "filtered" fuel level measured in whole gallons (or liters). When IPC reads more than 16.9 gallons, it displays "F". All readings between 16.9 and 2 gallons will display in whole gallon numbers only. When IPC reads fuel level as 2.0 gallons, the fuel gauge will display "E". When IPC reads fuel level as 1.0 gallon, "E" will flash and FUEL LEVEL VERY LOW message will display on DIC.
- If display is operating in DISPLAY OFF mode and fuel level falls below 4 gallons, all displays will illuminate and become active again. DIC will display CHECK FUEL GAUGE.
- Enter self-diagnostics and record all codes. See ENTERING SELF-DIAGNOSTICS under SELF-DIAGNOSTICS. If code I041 is set, see CODE I041 OR I042 - BATTERY VOLTAGE TOO LOW OR TOO HIGH. If code I041 is not set and fuel gauge operation is nonlinear or erratic, ensure all related terminal connections are good. Exit self-diagnostics.
- Remove fuel tank sending unit. If connector was disconnected during removal, reconnect sending unit to its harness connector, near filler tube on top of tank. Enter diagnostics to observe ID40 data value. Hand operate fuel sending unit float through full range of travel, watching for jumps or erratic data values. If sending unit does not move freely and/or data values jump, replace sending unit.
- If code I041 always reads empty, go to step 8). If code I041 always reads full, note data value of ID40 (fuel level). If data value reading is of actual gallons in tank and is much different than IPC fuel gauge display, replace IPC.
- If data value reading is 16 or more gallons, disconnect fuel tank sending unit connector. If data value reading is now 2 gallons or more, repair short to voltage in Purple wire circuit. See Fig 1. If a short is not found, replace IPC.
- If data value reading is less than 2 gallons, use DVOM to measure voltage at fuel sending unit harness connector between terminals "C" and "E". See Fig 2. If voltage is 10 volts or more, replace sending unit. If voltage is less than 10 volts, repair open in Black/White wire from terminal "E" to ground.
Courtesy of GENERAL MOTORS CORP.
Courtesy of GENERAL MOTORS CORP.
- If code I041 always reads empty, note data value of ID50. This is reading of ignition voltage to IPC. If voltage is less than 2 volts, repair open or short to ground in Pink/Black wire from IPC terminal C13 to engine compartment fuse block fuse A3. If voltage is between 2-10 volts, ensure good terminal connections at IPC C13 and repair charging system problem.
- If voltage is 10 volts or more, note data value of ID40 (fuel level). If value is same as actual fuel level in tank, replace IPC. If value is less than 3 gallons, with ignition on, close all doors and turn radio on. With doors still closed, turn off ignition.
- If radio turns off, repair open in power feed circuit (Pink/Black wire) to Retained Accessory Power (RAP) module and fuel tank sending unit between splice S402 and trunk fuse block fuse A11. See Fig 1. Splice S402 is located vertically behind left side of rear seat back, inside black tape wrapped harness, about 10 inches below top of cross panel. This is not "flat" type harness cover going into trunk. Splice S402 wire colors are Pink/Black.
- If radio continues to play, turn ignition on. Using DVOM, measure voltage between fuel sending unit harness connector terminals "C" and "E". If voltage is less than 10 volts, repair open in Pink/Black wire circuit from splice S402 to fuel sending unit connector. See previous step for location of splice S402.
- If voltage is 10 volts or more, use jumper wire to connect fuel sending unit harness connector terminals "C" and "F". Note data value of ID40. If value is more than 3 gallons, replace fuel sending unit. If value is less than 3 gallons, repair open or short to ground in Purple wire between IPC and fuel sending unit harness connector terminal "F".