Test Ac: Fuel Tank Temperature Sensor Circuit Failure (DTC B1222)
- Turn ignition switch to LOCK position. Disconnect Natural Gas Vehicle (NGV) module harness connector C1012. Install 60-pin Breakout Box (014-00322) following manufacturer's instructions. Leave NGV module disconnected. Turn ignition switch to RUN position. Using a voltmeter, measure voltage between breakout box pins No. 47 and 46. If voltage is more than 4.55 volts, go to next step. If voltage is 4.55 volts or less, go to step 5.
- Turn ignition switch to LOCK position. Disconnect fuel tank temperature sensor harness connector C351. Connector C351 is located on left center of vehicle on fuel tank. Using a fused jumper wire, connect Gray/Red wire terminal and Orange/Light Green wire terminal at fuel tank temperature sensor harness connector C351. Turn ignition switch to RUN position. Using a voltmeter, measure voltage between breakout box pins No. 47 and 46. If voltage is more than .12 volt, go to next step. If voltage is .12 volt or less, replace fuel tank temperature sensor.
- Turn ignition switch to LOCK position. Measure resistance in Gray/Red wire between fuel tank temperature sensor harness connector C351 and breakout box pin No. 46. If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in Gray/Red wire between NGV module, in-line connector C100 (located at left rear of engine compartment, below engine access cover), splice S316 (located at center of vehicle on fuel tank temperature sensor) and fuel tank pressure sensor.
- Measure voltage between breakout box pins No. 40 or 60 and No. 46. If voltage is .5 volt or less, go to next step. If voltage is more than .5 volt, repair short to voltage in Gray/Red wire between terminal No. 46 at NGV module harness connector C1012, in-line connector C100 (located at left rear of engine compartment, below engine access cover), splice S316 (located at center of vehicle on fuel tank temperature sensor) and fuel tank pressure sensor harness connector C349. Return to splice S316 and to fuel tank pressure sensor harness connector C351.
- Turn ignition switch to LOCK position. Disconnect fuel tank temperature sensor harness connector C351 (located on left center of vehicle on fuel tank). Turn ignition switch to RUN position. Using a voltmeter, measure voltage between breakout box pins No. 47 and 46. If voltage is 4.55 volts or less, go to next step. If voltage is more than 4.55 volts, replace fuel tank temperature sensor.
- Turn ignition switch to LOCK position. Using an ohmmeter, measure resistance between breakout box pins No. 40 and 46. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to ground in Gray/Red wire between terminal NGV module, in-line connector C100 (located at left rear of engine compartment, below engine access cover), splice S316 (located at center of vehicle on fuel tank temperature sensor) and fuel tank pressure sensor.
- Connect fuel tank temperature sensor harness connector C351. Connect accessory voltmeter leads to NGS tester. Connect positive lead on NGS tester to breakout box pin No. 47 and negative lead to pin No. 40. Turn ignition switch to RUN position. Enter DIGITAL MEASUREMENT SYSTEM on NGS tester. Select VOLTMETER, then LINK. Select PID/DATA, then NGV. Select TEMPS1, then START. Select REC, then press TRIGGER to capture data. Press TRIGGER again to store data, then select VIEW to examine data. If voltage varies rapidly between .2-4.9 volts, repair intermittent contact condition. If voltage does not vary rapidly between .2-4.9 volts, replace NGV module.
CAUTION:
New Generation Star (NGS) tester must be used in this procedure to measure voltage. Using a standard DVOM to carry out this test will cause an inaccurate reading, possibly leading to inaccurate repairs.