DTC P0723 Output Speed Sensor Intermittent. Chevrolet Chevy Suburban

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1996 🢒 Chevy Suburban - 4WD 🢒 Transmission/Transaxle 🢒 Automatic Transmission - 4L80-E 🢒 DTC P0723 Output Speed Sensor Intermittent

Automatic Transmission Components 6.5L Diesel
Automatic Transmission Controls Schematics 6.5L
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The speed sensor circuit consists of a magnetic induction type sensor, a Vehicle Speed Sensor (VSS) buffer module and wiring. Gear teeth pressed onto the output shaft 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 AC VSS signal into a 40 pulse per revolution (PPR) DC signal on circuit 437 to indicate transmission output speed.

When the PCM detects an unrealistically large change in the Output Shaft Speed Sensor reading, then DTC P0723 sets. DTC P0723 is a type A DTC.

Conditions for Setting the DTC

•	No 4WD Low DTC P1875.

•	No TFP Val. Position Sw. assembly change for greater than 2 seconds.

•	The engine must be running.

•	The vehicle is not in 4 Wheel Drive Low.

•	RPM decrease decreases greater than 1000 RPM while in a Drive gear for at least 2 seconds.

•	The PCM sets the Malfunction Indicator Lamp (MIL).

Action Taken When the DTC Sets

•	The PCM defaults to maximum line pressure.

•	The PCM freezes shift adapts.

•	The PCM defaults to the calculated output speed value using the ISS Sensor values.

Conditions for Clearing the DTC

The PCM turns OFF the MIL after three consecutive ignition cycles 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 VCM.

Diagnostic Aids

•	Inspect the wiring for poor electrical connections at the PCM. Inspect the wiring for poor electrical connections at the transmission 20-way connector. Look 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

•	When diagnosing for an intermittent short or open condition, 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 tests the voltage supply to the VSS buffer module.

This step tests the integrity of the ground circuit.

P0723

Step

Action

Value(s)

Yes

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Install the scan tool (tech 1) ®.
With the engine OFF, turn the ignition switch to the RUN position.

Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data.

Record the DTC Freeze Frame and Failure Records and DTCs.
Raise the drive wheels.
Start the engine and place the transmission in Drive range.

Does the Trans OSS RPM increase with the drive wheel speed?

+200 RPM

The problem is intermittent. Go to Diagnostic Aids

Go to Step 3

Turn the ignition OFF.
Disconnect the OSS Sensor connector at the component.
Connect a J 39200 DVOM on AC Voltage scale between terminals A and B at the OSS Sensor.
Turn the ignition On, and start the engine.
Place the transmission in Drive range

Does the voltage read within specifications?

Greater than 7 volts, at greater than 10 mph

Go to Step 4

Go to Step 16

Turn the ignition OFF.
Reconnect the OSS Sensor harness.
Turn the ignition ON and the engine OFF.
Disconnect the Signal Buffer Module harness.
Set the J 39200 DVOM on the AC volts scale.
Connect the J 39200 DVOM between terminals C7 and C12 of the Signal Buffer Module harness.
Start the engine.
Place the transmission in a drive range.

Is the voltage within the specified range?

Greater than 7 volts, at greater than 10 mph

Go to Step 5

Go to Step 10

Inspect circuit 821 and circuit 822 for an open.
Inspect circuit 821 and circuit 822 for a short.

Did you find and correct a problem?

Go to Step 11

Go to Step 6

With the engine OFF, turn the ignition switch ON.
Check for ignition voltage at terminal C9 of the Signal Buffer Module harness.

Is ignition voltage present?

Go to Step 7

Go to Step 12

Connect a test lamp to a known good voltage source.
Probe terminal C8 of the Signal Buffer Module harness.

Did the test lamp light?

Go to Step 8

Go to Step 13

Turn the ignition OFF.
Reconnect the Signal Buffer Module harness to the Signal Buffer Module.
Start the engine.
Place the transmission in a drive range.
Set the J 39200 DVOM on the DC volts scale.
Back probe terminal C15 of the Signal Buffer Harness connector with the J 39200 DVOM.

Does the voltage increase with the drive wheel speed?

Go to Step 9

Go to Step 14

Check circuit 389 for continuity.

Refer to Section 8.

Did you find a problem?

Go to Step 15

Go to Step 16

Replace the OSS Sensor.

Refer to Automatic Transmission Output Shaft Speed Sensor Replacement, in On-Vehicle Service.

Is the replacement complete?

Go to Step 17