DTC B2957 Security System Sensor Data Circuit Low. Chevrolet Astro

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1999 🢒 Astro - 2WD 🢒 Body and Accessories 🢒 Theft Deterrent 🢒 DTC B2957 Security System Sensor Data Circuit Low

Theft Deterrent System Components
Theft Deterrent System Schematics
Theft Deterrent System Schematic Icons
Theft Deterrent System Schematic Icons

Circuit Description

The Passlock module will read an analog voltage from the Passlock sensor. Based on an internal reference, the Passlock module will determine if the measured voltage is open, shorted to ground, a valid code, or a tamper code. there are 10 possible valid code combinations. The Passlock module will only accept the last learned valid code.

Conditions for Setting the DTC

•	The ignition switch is ON.

•	The Passlock sensor signal input is less than 0.4 volts for 1 second after turning the ignition switch to the crank position.

Action Taken When the DTC Sets

•	The vehicle will not run if the fault occurs before the vehicle is started. The security telltale will flash for 10 minutes and then turn ON steady.

•	If the vehicle is running when the fault occurs, the Passlock module will be in the fail enabled mode allowing the vehicle to start and run. The security telltale will be ON.

Conditions for Clearing the DTC

•	The DTC will clear after an ignition cycle has occurred without the fault.

•	Passlock module history codes will be cleared after 100 ignition cycles with no current codes active.

•	Using a scan tool

Diagnostic Aids

•	When replacing the Passlock sensor, all the sensor components; the lock, the sensor, the filter, and the harness, are included as a replacement part and must be replaced.

•	Use the scan tool in order to test the Passlock data voltage and the Passlock code.

•	Perform a visual inspection of the wiring and the connectors.

•	Inspect the Passlock sensor harness for an intermittent or poor connections (including the in-line connector). Refer to Intermittents and Poor Connections .

Test Description

The numbers below refer to the numbers on the diagnostic table.

This step tests for a short to ground in CKT 1836.

This step tests for the 5 volt reference in the Passlock module in order to determine if the module or the Passlock sensor need to be replaced.

Step

Action

Value(s)

Yes

Did you perform the VTD Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

Turn the ignition switch OFF.
Disconnect the Passlock module connector. Refer to Theft Deterrent Module Replacement .
Use a J 39200 digital multimeter (DMM) in order to measure the resistance from the Passlock/EVO module connector terminal B7 to ground.

Is the resistance within the specified value?

(OL) infinite

Go to Step 3

Go to Step 6

Reconnect the Passlock module.
Connect a fused jumper between the Passlock module connector terminal B8 and terminal B3.
Use a scan tool in order to read the Passlock code.

Does the Passlock code read open?

Go to Step 4

Go to Step 5

Remove the jumper.
Replace the Passlock sensor in the electronic column lock module assembly.

•	With Tilt Wheel

-	To disassemble the lock module assembly, refer to Electronic Column Lock Module - Disassemble - Off Vehicle in Steering Wheel and Column - Tilt.

-	To assemble the lock module assembly, refer to Electronic Column Lock Module - Assemble - Off Vehicle in Steering Wheel and Column - Tilt.

•	With Standard Wheel

-	To disassemble the lock module assembly, refer to Electronic Column Lock Module - Disassemble - Off Vehicle in Steering Wheel and Column - Standard.

-	To assemble the lock module assembly, refer to Electronic Column Lock Module - Assemble - Off Vehicle in Steering Wheel and Column - Standard.

Is the repair complete?

Go to Step 7

Remove the jumper.
Replace the Passlock module. Refer to Theft Deterrent Module Replacement .

Is the repair complete?

Go to Step 7

Repair the short to ground in CKT 1836.

Is the repair complete?

Go to Diagnostic System Check - Theft Deterrent

Reconnect all of the previously disconnected connectors and the components.
Turn the ignition switch ON.
Connect the scan tool.
Clear the DTCs.
Perform one of the following Passlock reprogramming procedures:

•	PASSLOCK Reprogramming Seed and Key

•	PASSLOCK Reprogramming Auto Learn

Is the repair complete?

Go to Diagnostic System Check - Theft Deterrent