DTC B1720: Fuel Level Resistance Fault
- Disconnect Brown 4-pin fuel level sensor connector located under rear seat. Connect test light between fuel level sensor connector terminal No. 3 (Yellow/White wire) and battery positive voltage. See Fig 1
. If test light comes on, go to next step. If test light does not come on, repair open circuit in Yellow/White wire between fuel level sensor connector terminal No. 3 and Main Instrument Unit (MIU) 12-pin connector terminal No. 8. See Figure
.
- Use Tech 1 scan tool to read fuel level value. If fuel level value is 5 volts, go to next step. If fuel level value is not 5 volts, repair open circuit in Gray/White wire between MIU 12-pin connector terminal No. 9 and fuel level sensor connector terminal No. 4. After repair, go to step 5
.
- Connect jumper wire between fuel level sensor connector terminals No. 3 (Yellow/White wire) and No. 4 (Gray/White wire). Use Tech 1 scan tool and read fuel level value. If value is zero volts, go to next step. If value is not zero volts, repair short circuit in Gray/White wire between MIU 12-pin connector terminal No. 9 and fuel level sensor connector terminal No. 4. After repair, go to step 5
.
- Check Yellow/White and Gray/White wire between fuel level sensor connector and MIU 12 pin connector terminals No. 8 and 9. Repair as necessary, then go to next step. If wiring is okay, replace fuel level sensor, then go to next step.
- Use scan tool to clear all DTCs. Perform a functional test to determine whether DTC reoccur. If DTC does not reoccur, system is okay. If DTC reoccurs, replace MIU ECU. See ELECTRONIC CONTROL UNIT (ECU)
under REMOVAL & INSTALLATION.
Courtesy of SAAB-SCANIA OF AMERICA, INC.