DTC P0723 Output Speed Sensor Circuit Intermittent Diesel Only
Circuit Description
The speed sensor circuit consists of a magnetic induction type sensor, which is the Output Shaft Speed (OSS) Sensor, a Vehicle Speed Sensor (VSS) Buffer Module, and wiring. Gear teeth pressed onto the output shaft carrier assembly induce an alternating voltage into the sensor. This signal transmits to the VSS Buffer Module. The VSS Buffer Module compensates for various final drive ratios. The VSS Buffer Module also converts the alternating current (AC) OSS signal into a 40 pulse per revolution (PPR) 5-volt DC square wave form signal on circuit 437 to indicate transmission output speed.
If the PCM detects an unrealistically large change in the Output Shaft Speed (OSS) Sensor reading, then DTC P0723 sets. DTC P0723 is a type B DTC.
Conditions for Setting the DTC
| • | No TFP Val. Position Sw. DTC P1810. |
| • | No 4WD Low DTC P1875. |
| • | No TFP Val. Position Sw. change for greater than 6 seconds. |
| • | The engine must be running more than 475 RPM for at least 7 seconds. |
| • | System voltage is 9.0-16.0 volts. |
| • | The vehicle is not in 4 Wheel Drive Low. |
| • | No 4WD Low Switch status change for 2 seconds. |
| • | The OSS RPM decrease is greater than 1000 RPM while in a Drive gear for at least 3.5 seconds. |
Action Taken When the DTC Sets
| • | The PCM illuminates the Malfunction Indicator Lamp (MIL). |
| • | The PCM commands maximum line pressure. |
| • | The PCM freezes shift adapts. |
| • | The PCM defaults to the calculated output speed value using the ISS Sensor values. |
| • | DTC P0723 is stored in PCM history. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL after three consecutive trips without a failure reported. |
| • | A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported. |
| • | The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | Inspect the wiring at the PCM, the A/T OSS, the VSS Buffer Module connectors and all other circuit connecting points for the following conditions: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| - | Moisture intrusion |
| - | Corrosion |
| • | It may be necessary to drive the vehicle. |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies the fault condition.
-
This step verifies the OSS Sensor and circuit output to the VSS Buffer Module.
-
This step tests the voltage supply to the VSS Buffer Module.
-
This step tests the integrity of the ground circuit.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear Info function will erase the stored Freeze Frame and Failure Records from the PCM. Does the Transmission OSS drop or fluctuate more than the specified value? | 1000 RPM | No fault verified at this time. Go to Diagnostic Aids | ||||||
3 |
Does the voltage drop or fluctuate at 2000 RPM? | -- | ||||||
Does the voltage drop or fluctuate at 2000 RPM? | Greater than 2.0 volts AC | |||||||
5 | Inspect circuit 821 and circuit 822 for an intermittent open. Refer to General Electrical Diagnosis Procedures. Did you find the condition? | -- | ||||||
6 | Inspect circuit 821 and circuit 822 for an intermittent short together or a short to ground. Refer to General Electrical Diagnosis Procedures. Did you find the condition? | -- | -- | |||||
Is the voltage greater than the specified value? | 10.5 volts DC | |||||||
8 | Repair the intermittent open or high resistance in circuit 39. Refer to Wiring Repairs. Is the repair complete? | -- | -- | |||||
Is the voltage greater than the specified value? | 10.5 volts DC | |||||||
10 | Repair the open or high resistance in circuit 451 (ground). Refer to Wiring Repairs. Is the repair complete? | -- | -- | |||||
11 |
Is the voltage steady and within the specified value? | 4.8-5.2 volts DC | ||||||
12 | Repair the short in circuit 821 and circuit 822. Refer to Wiring Repairs. Did you correct the condition? | -- | -- | |||||
13 |
Is the voltage reading steady within the specified value? | 1.5-3.5 volts DC | ||||||
14 | Is the voltage from step 11 greater than the specified value? | 5.2 Volts DC | ||||||
15 | Inspect for a short to power in circuit 437. Refer to General Electrical Diagnosis Procedures. Did you find the condition? | -- | ||||||
16 | Inspect circuit 437 for continuity or short to ground. Refer to General Electrical Diagnosis Procedures. Did you find the condition? | -- | ||||||
17 | Replace the OSS Sensor. Refer to Speed Sensor Replacement, in On-Vehicle Service. Is the replacement complete? | -- | -- | |||||
18 | Replace the VSS Buffer Module. Is the replacement complete? | -- | -- | |||||
19 | Inspect the PCM terminals and connector for improper tension or corrosion. Did you find the condition? | -- | ||||||
20 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the replacement complete? | -- | -- | |||||
21 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
