TSB : Test Ab: Fuel Tank Pressure Sensor Circuit Short To Voltage (DTC B1220)

Details

Turn ignition switch to RUN position. Using New Generation Star (NGS), monitor Natural Gas Vehicle (NGV) module PID TANKPR. If PID indicates zero psi, go to next step. If PID does not indicate zero psi, check connectors for loose and corroded pins. If all connections are clean and tight, clear DTCs. Using NGS tester, perform NGV module self-test. If DTC B1220 is retrieved again, replace NGV module. Turn ignition switch to LOCK position. Disconnect NGV module harness connector C1012. Install 60-pin Breakout Box (014-00322) following manufacturer's instructions. Leave NGV module disconnected. Disconnect fuel tank pressure sensor harness connector C349. Connector C349 is located on left center of vehicle on fuel tank. Turn ignition switch to RUN position. Measure voltage between breakout box pins No. 7 and No. 46. If voltage is more than .61 volt, go to next step. If voltage is .61 volt or less, replace fuel tank pressure sensor. See FUEL TANK PRESSURE SENSOR under REMOVAL & INSTALLATION. Turn ignition switch to LOCK position. Measure resistance between breakout box pins No. 7 and 26. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short between Red/Pink and Brown/White wires. Turn ignition switch to RUN position. Measure voltage at breakout box pins No. 7 and 37 or 57. If battery voltage is not present, go to next step. If battery voltage exists, repair short to voltage in Red/Pink wire between terminal No. 7 at NGV harness connector C1012, in-line connector C100 (located at left rear of engine compartment, below engine access cover) and fuel tank pressure sensor harness connector C349. Check operation of fuel tank solenoids. See appropriate SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE. If fuel tank solenoids operate properly, go to next step. If fuel tank solenoid(s) do not operate properly, repair fuel tank solenoid(s) as necessary. Check fuel system for leaks. If fuel system leaks, repair as necessary. If fuel system does not leak, replace NGV module.