Fuel Gauge Indicates Full Or Greater At All Times (Single Tank - 4.3L)
- Disconnect fuel pump and sender connector. Install jumper wire between fuel pump and sender connector terminals "A" (Purple/White wire) and "B" (Black wire). If fuel gauge indicates full, go to next step. If fuel gauge indicates empty, replace fuel pump and sender.
- Connect jumper wire between fuel pump and sender terminal "A" and ground. If fuel gauge indicates full, go to next step. If fuel gauge indicates empty, locate and repair high resistance in Black wire between fuel pump and sender and Vehicle Control Module (VCM). If high resistance is not found, replace VCM.
- Connect a fused jumper wire between fuel tank sender module connector terminal "C" (Purple/White wire) and ground. See Fig 1
. If fuel gauge indicates full, go to next step. If fuel gauge indicates empty, locate and repair open Purple/White wire between fuel pump and sender and fuel tank sender module. See WIRING DIAGRAM
.
- Connect a fused jumper wire between fuel tank sender module connector terminal "L" (Purple wire) and ground. If fuel gauge indicates empty, go to next step. If fuel gauge indicates full, locate and repair open Purple wire between fuel tank sender module and instrument cluster. If Purple wire is okay, replace instrument cluster.
- Disconnect fuel tank sender module. Using DVOM, measure voltage between fuel tank sender module connector terminal "B" (Gray wire) and ground. If voltage is 4.0-5.5 volts, go to next step. If voltage is zero, locate and repair open Purple wire between fuel tank sender module and VCM.
- Measure voltage between fuel tank sender module connector terminal "A" (Pink wire) and ground. If voltage reading is battery voltage, go to next step. If voltage reading is zero, locate and repair open Pink wire between fuel tank sender module and fuse.
- Connect self-powered test light between fuel tank sender module connector terminal "M" and ground. If test light illuminates, replace fuel tank sender module. If test light does not illuminate, locate and repair open Black/White wire between fuel tank sender module and VCM. If Black/White wire is okay, replace VCM.
Courtesy of GENERAL MOTORS CORP.