Diagnostic Aids
Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following:
- Output Shaft Speed (OSS) Sensor
- Wiring Harness Circuits (OSS & SIG RTN)
- Powertrain Control Module (PCM)
Fig 1: Identifying Output Shaft Speed Sensor Circuits & Harness Connector Terminals (B2300, B2500, B3000 & B4000 With 4R70W Automatic Transmission)
Fig 2: Identifying Output Shaft Speed Sensor Circuits & Harness Connector Terminals (B2300, B2500, B3000 & B4000 Without 4R70W Automatic Transmission)
- 1) Continuous Memory DTC P0720, P0721, P0722, P0723 & P1900: Verify Drive Cycle
Using scan tool, select OSS PID from PID/DATA MONITOR & RECORD menu. Road test vehicle and observe OSS PID value. Shift transmission through all gear ranges, shift up and down. If OSS PID value increases and decreases with engine and vehicle speed, go to next step. If OSS PID value does not increase and decrease with engine and vehicle speed, go to step 5). - 2) Visual Inspection
Turn ignition switch to OFF position. Disconnect OSS sensor connector located on side of transmission. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. If connector is okay, fault is unable to be duplicated at this time. Go to TEST Z, step 1) and check for intermittent faults. - 3) Check VPWR To OSS Sensor
Turn ignition switch to OFF position. Disconnect OSS sensor connector. Turn ignition switch to ON position. Using a DVOM, measure VPWR circuit voltage between ground and OSS sensor harness connector. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in OSS circuit. - 4) Check PWR GND To OSS Sensor
Ensure ignition switch is turned to OFF position. Using a DVOM, measure resistance between negative battery terminal and OSS sensor harness connector PWR GND terminal. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in PWR GND circuit. - 5) Check OSS Circuit For Short To VPWR
Disconnect OSS sensor connector, if not already disconnected. Turn ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal and OSS sensor harness connector OSS terminal. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to VPWR in OSS circuit. - 6) Check OSS & SIG RTN Circuits For Open In Harness
Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistances of OSS and SIG RTN circuits between PCM harness connector and OSS sensor harness connector. If both resistance measurements are less than 5 ohms, go to next step. If either resistance measurement is 5 ohms or more, repair open in OSS or SIG RTN circuit. - 7) Check OSS Circuit For Short To SIG RTN Circuit Or Chassis Ground
Using a DVOM, measure resistance between OSS sensor harness connector OSS and SIG RTN terminals. Also, measure resistance between chassis ground and OSS sensor harness connector OSS terminal. If either resistance measurement is 10 k/ohms or less, repair short to chassis ground or SIG RTN circuit in OSS circuit. If both resistance measurements are more than 10 k/ohms, go to next step. - 8) Check Resistance Of OSS Sensor
Using a DVOM, measure resistance between OSS sensor terminals. If resistance is 450-750 ohms, replace PCM. If resistance is not 450-750 ohms, replace OSS sensor. - 9) Check OSS Signal Output To PCM (Hall-Effect Type)
Raise and support front of vehicle so that front wheels can rotate freely. Turn ignition switch to ON position and place gearshift lever in Neutral. Using a DVOM, measure voltage between PCM harness connector terminals No. 58 (OSS) and No. 103 (PWR GND) while rotating one wheel with opposite wheel held stationary. If voltage pulses from less than one volt to more than 5 volts, replace PCM. If voltage is not as specified, replace OSS sensor.