My car won't start have replaced pcm, bcm, fuel pump, fuel pressure regulator, passlock system, emergency flasher, when I turn on the turn signals the emergency flasher buzzes, and it quits running, and will not start.

DTC P1631 Theft Deterrent Fuel Enable Signal Not Correct

The powertrain control module (PCM) controls the fuel injector operation and the starter operation based on a vehicle theft deterrent (VTD) password from the vehicle body control module (BCM). When the ignition is first turned ON, the BCM sends a programmed theft deterrent password to the PCM. The PCM acknowledges the password and responds to the BCM that normal fuel injector and starter operation will continue. If the PCM detects an incorrect password, a theft deterrent system failure, or an attempted vehicle theft, DTC 1631 will set. The engine will not start or crank as long as the condition is present.

Diagnostic Aids
DTC P1631 indicates that the vehicle theft deterrent password that the PCM has learned does not agree with the password received from the VTD system. This condition can occur if the BCM has been replaced and the PCM Password Learn function has not been enabled. If the BCM has been replaced, the password must be relearned.


Step
Action
Yes
No
1
Did you perform the Diagnostic System Check - Vehicle?
Go to Step 2
Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2
Perform the Password Learn Procedure. Refer to Programming Theft Deterrent System Components .
Did you complete the procedure?
System OK

30-Minute Learn Procedure
Turn ON the ignition, with the engine OFF.
Attempt to start the engine, then release the key to ON; the vehicle will not start.
Observe the SECURITY telltale. After approximately 10 minutes, the telltale will turn OFF.
Turn OFF the ignition, and wait 5 seconds.
Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes. The vehicle is now ready to relearn the Passlock™ Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK.
Important: The vehicle learns the Passlock™ Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.
Start the engine. The vehicle has now learned the Passlock™ Sensor Data Code and/or password.
With a scan tool, clear any DTCs if needed. History DTCs will self clear after 100 ignition cycles.

Sounds like a security system problem. Do this, turn the ignition switch to start but don't start the engine, then leave the switch in the run position, watch the theft light it will be on steady or flashing, wait for the light to change then turn the switch off then repeat up to 2 more times, it takes about 10 minutes per cycle don't try to hurry and if the car accidentally starts and quits start over. Occasionally the vehicle will start and run after the second try but don't count on it, I hope this helps, take care.

No you didn't ! you only think you did . Turn signal switch has nothing to do with it .
Ignition Lock Cylinder and Housing
The ignition lock cylinder is located at the upper right side of the steering column. The Passlock™ sensor is in the steering column. The Passlock™ sensor is separate from the key and lock cylinder. The key and the lock cylinder work together in order to determine if the proper ignition key was used to start the vehicle.
In the event of an open Class 2 serial data line between the BCM and the VCM/PCM, the vehicle will become fail-enabled if the VCM/PCM has already received the password from the BCM for that ignition cycle (the engine is running). In this event, the following conditions occur:
• The security telltale will be ON continuously.
• The VCM/PCM will become fail-enabled for future ignition cycles.
If a failure in the Class 2 serial data line occurs before the ignition cycle, when the VCM/PCM is not fail-enabled, the following conditions occur:
• The VCM/PCM will never receive a valid password in order to enable the fuel injectors.
• The vehicle will not start.

The design of the passlock™ system is to prevent the vehicle operation if the proper ignition key is not used in order to start the vehicle. The mechanical key, in normal operation, will turn the passlock™ lock cylinder. The passlock™ sensor will relay the passlock™ data to the body control module (BCM). The BCM will determine the validity of the passlock™ data. The BCM will send a code password to the vehicle/powertrain control module (VCM/PCM). When the VCM/PCM receives the correct code the VCM/PCM allows the fuel injectors to operate normally. The passlock™ system requires the VCM/PCM and the BCM to communicate the various functions in order to operate. These functions transmit over the class 2 serial data line CKT 1807. For an explanation of the class 2 serial data operation refer to Data Link Connector Circuit Description in Wiring Systems.
Your best bet , take it to a qualified repair shop , there is a real possibility of rendering your vehicle useless if you don't know what your doing

How is the battery ? Do the headlamps shine bright ? Did you check the crank relay an the crank fuse 40amp ? one of the big one's ,maxi fuse . Under hood fuse / relay box . Check to see if voltage is coming through the transaxle range switch.

When the ignition switch is on, battery voltage is applied to one side of the crank relay in the underhood accessory wiring junction block through circuit 3, the PCM-BCM Fuse in the fuse block, and circuit 439. When the ignition switch is turned to START, voltage is fed to the powertrain control module connector C2 terminal 23 through circuit 5, the CRANK SIGNAL Fuse in the fuse block, and circuit 806 through the underhood accessory wiring junction block. Power is always provided from the CRANK MaxiFuse in the underhood accessory wiring junction block to the common side of the crank relay contacts. When the powertrain control module sees the crank signal and determines that conditions are OK for a crank, it supplies ground through circuit 625 to the crank relay. The crank relay now has both power and ground to the relay coil, causing the relay to pull in. When this happens, and the gear selector is in either PARK or NEUTRAL, the power at the relay common contact is passed through circuit 1737, the transaxle range switch and circuit 6 to the S terminal on the starter solenoid.
Passlock Theft Deterrent System
This vehicle is equipped with the Passlock theft deterrent system. This system contains a Passlock sensor. The Passlock sensor is part of the ignition lock cylinder assembly. The Body Control Module (BCM) interfaces with the Passlock sensor.
When turning the ignition switch to the START position with the proper key, the Passlock sensor generates an analog voltage signal, which is sent to the BCM. This analog voltage signal is of a specific value to the vehicle, and varies from vehicle to vehicle. When attempting to start the engine, the BCM compares a preset stored analog voltage value with the signal coming from the sensor. Because both values match, the BCM sends a fuel enable password via the Class II Serial Data Line to the Powertrain Control Module (PCM). As a result, the PCM enables the crank relay, and allows fuel delivery to the engine.
When attempting to start the engine by means other than using the proper key in the ignition switch, the Passlock sensor sends a analog voltage signal of a different value. The BCM compares the preset stored analog voltage value with the signal coming from the sensor. Because both values do not match, the BCM sends a fuel disable password via the Class II Serial Data Line to the Powertrain Control Module (PCM). As a result, the PCM disables the crank relay, and does not allow fuel delivery to the engine.
For more information regarding the Passlock theft deterrent system, refer to Theft Deterrent in Body and Accessories
This starting system is computer controlled , if you are not familiar with this I suggest you take a GM dealership or an ASE certified repair shop .

There is a problem with the system an there is a DTC - diagnostic trouble code stored in the body control module !
The vehicle theft deterrent system is designed in order to prevent vehicle theft by disabling the fuel injectors unless the lock cylinder is engaged by the correct mechanical key. The theft deterrent system uses the following 4 components for theft prevention:
?€¢
The lock cylinder

?€¢
The ignition switch

?€¢
The body control module (BCM)

?€¢
The powertrain control module (PCM)

When starting the engine, the PCM searches for a password from the BCM through the Class 2 serial data circuit. If the password is not recognized or not present, the PCM will disable the fuel injectors. Two modes of tamper detection are provided:
?€¢
No password received

The engine will start and stall quickly. SECURITY telltale will flash on the instrument panel cluster (IPC) and then stay ON steady.

?€¢
Incorrect or disable password received (More than 3 invalid passwords are received)

The engine is disabled for at least 10 minutes and the SECURITY telltale will illuminate solid on the IPC during the 10 minutes.

After the vehicle has passed theft detection, the PCM will continue normal operation
Ignition Switch
The mechanical key and lock cylinder is located on the steering column. The main electrical switching portion of the assembly is separate from the key and lock cylinder. The VTD portion of the ignition switch is the Passlock?"¢ cylinder.
The Passlock?"¢ lock cylinder is a locking cylinder that turns a magnet past a stationary hall effect sensor. When turned to crank, the hall effect sensor is latched which applies a fixed resistance to the Passlock?"¢ signal data circuit. The voltage measured by the BCM on the Passlock?"¢ signal data circuit is the Passlock?"¢ data value.
Body Control Module (BCM)
The BCM compares the Passlock?"¢ data value to a value that it has stored in memory. If the values match the BCM sends a password via the class 2 serial data line to the PCM.
Powertrain Control Module (PCM)
When the PCM receives the correct password, the PCM enables the fuel injection system, allowing the vehicle to operate correctly. The PCM may allow the car to start and quickly stall during a failed theft condition.
If the BCM does not receive a Passlock?"¢ data value, the BCM will enter a short tamper mode. During this mode, the VTD system will not allow the car to operate for 4 seconds.
If the Passlock?"¢ data value is incorrect, the VTD system will enter the long tamper mode. In the long tamper mode, the following actions will occur:
?€¢
The THEFT SYSTEM indicator will flash.

?€¢
The fuel injectors will be shut off for approximately 10 minutes.

Although the vehicle may start, the engine will quickly stall due to a fuel cut-off.
In the event of an open in the serial data communication between the BCM and the PCM or a failure in the Passlock?"¢ lock cylinder, the following actions occur:
?€¢
The VTD system will become fail-enabled if the car has already passed theft for that ignition cycle (i.e. the engine is running).

?€¢
The PCM or the BCM may set diagnostic trouble codes (DTCs).

?€¢
The THEFT SYSTEM indicator will light continuously.

?€¢
The PCM will become fail-enabled for future ignition cycles.

If a failure occurs when the ignition is off, while the VTD system is not fail-enabled, the PCM will never receive a valid password, and will not allow vehicle operation by disabling the fuel injectors. An this system can set 6 DTC'S
DTC B2947 Security System Sensor Power CKT Low DTC B2948 Security System Sensor Power CKT High DTC B2957 Security System Sensor Data Circuit Low DTC B2958 Security System Sensor Data Circuit High DTC B2960 Sec Sys Sensor Data Incorrect but Valid DTC B3031 Security System Controller in Learn Mode DTC B3033 Security System Indicates Tamper

Did you change the lock cylinder ? You need to put the passlock?"¢ sensor out of your old steering column into the replacement one. Is the security light lit in the instrument cluster ?
The design of the passlock?"¢ system is to prevent the vehicle operation if the proper ignition key is not used in order to start the vehicle. The mechanical key, in normal operation, will turn the ignition lock cylinder. The passlock?"¢ sensor monitoring the position of the lock cylinder will relay the passlock?"¢ data to the body control module (BCM). The BCM will determine the validity of the passlock?"¢ data. The BCM will send a password to the vehicle/powertrain control module (VCM/PCM). When the VCM/PCM receives the correct password the VCM/PCM allows the fuel injectors to operate normally. The passlock?"¢ system requires the VCM/PCM and the BCM to communicate the various functions in order to operate. These functions transmit over the class 2 serial data line CKT 1807. For an explanation of the class 2 serial data operation refer to Data Link Communications Circuit Description in Data Link Communications

You don't need to program key's with this anti-theft system , there is no chip inside . Did you get a correct lock cylinder. . On this system there is a pass lock sensor in side an the lock clinder has a magnet !
Passlock™ Sensor
The passlock™ sensor is inside the upper right side of the steering column. The passlock™ sensor contains 2 hall effect sensors. The tamper hall effect sensor is on the top. The security hall effect sensor is under the tamper hall effect sensor. Both of the hall effect sensors monitor the magnet of the lock cylinder through an opening. The tamper hall effect sensor is physically placed on top of the security hall effect sensor. This arrangement enables the tamper hall effect sensor to engage first if an intruder attempts to bypass the passlock™ sensor by placing a large magnet around that area of the steering column. There is a tamper resistor inside the passlock™ sensor in order to help prevent tamper to the system. Passlock™ equipped vehicles have a selection of 10 different security resistors ranging from 0.5K ohms up to 13.6K ohms. Installing one of the security resistors inside the passlock™ sensor will generate a unique passlock™ code. All 10 combinations of the passlock™ sensor have the same part number. However, you cannot simply replace the passlock™ sensor and expect the system to operate properly. Always start by performing the Diagnostic System Check first and following the instructions.
Body Control Module
The Body Control Module (BCM) contains the theft deterrent system logic. The BCM reads the passlock™ data from the passlock™ sensor. If the passlock™ data is correct, the BCM will pass theft. The BCM will then transmit the code password to the VCM/PCM.
During the tamper mode the vehicle may start. The vehicle will then stall. If the BCM receives the wrong passlock™ data, the VTD will immediately go into the tamper mode. The tamper mode will lock-out the vehicle fuel injectors for 10 minutes. The SECURITY indicator will flash while the VTD is in the tamper mode.
If the passlock™ sensor sends a correct password to the BCM when the ignition is in the ON position, the BCM will send a fuel enable signal to the VCM/PCM. The VCM/PCM will not disable the fuel due to any BCM message for the remainder of the ignition cycle.

You only need to do a relearn if one of these are replaced
Use this procedure after replacing:
• Passlock™ Sensor
• BCM
• VCM
• PCM

Did you replace any of these ?

30 Minute Re-Learn Procedure
Turn ON the ignition, with the engine OFF.
Attempt to start the engine, then release the key to ON (vehicle will not start).
Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF.
Turn OFF the ignition, and wait 5 seconds.
Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes ( the vehicle is now ready to relearn the Passlock™ Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK).
Important: The vehicle learns the Passlock™ Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.
Start the engine (the vehicle has now learned the Passlock™ Sensor Data Code and/or password).
With a scan tool, clear any DTCs if desired (history DTCs will self clear after 100 ignition cycles).

Do you have a second key ?
Passlock™ System
The theft deterrent system has been incorporated into the body control module (BCM). The theft deterrent is provided in order to prevent vehicle operation if the correct key is not used in order to start the vehicle. The ignition key turns the lock cylinder. The cylinder rotation produces an analog voltage code in the Passlock™ sensor. This voltage code is received by the BCM. The BCM compares the voltage code to the previously learned voltage code. If the codes match, a class 2 message is sent from the BCM to the powertrain control module (PCM)/vehicle control module (VCM). The message enables the fuel injectors.
The design of the Passlock™ system is to prevent vehicle theft by disabling the engine unless the ignition lock cylinder rotates properly by engaging the correct ignition key. The system is similar in concept to the PASS-Key® system. However, the Passlock™ system eliminates the need for a key mounted resistor pellet. The components of the Passlock™ system are as follows:
• The ignition lock cylinder
• The ignition switch
• The Passlock™ sensor
• The BCM
• The security telltale
• The VCM/PCM

Your best bet , take it to a qualified repair shop . Security light on - DTC'S - diagnostic trouble codes are stored . Having codes check would point in a diagnostic procedure to fix the issue .

DTC B2947
DTC B2948
DTC B2957
DTC B2958
DTC B2960
DTC B3031
DTC B3033
DTC P1626
DTC P1631
Circuit Description
The Passlock™ system is provided in order to prevent vehicle theft if the ignition lock cylinder is forced to rotate or the ignition switch is operated while separated from the ignition lock cylinder case. The body control module (BCM) provides security system sensor power and low reference for the Passlock™ sensor. The BCM also measures the security system sensor voltage.
When the correct key is used to start the vehicle, a magnet on the lock cylinder passes close to the Passlock™ sensor within the ignition lock cylinder case. The magnet activates the security hall effect sensor in the Passlock™ sensor which completes a circuit from the security sensor signal circuit through a resistor to the security sensor low reference circuit. The resistance value will vary from vehicle to vehicle. The BCM will measure the voltage on the security sensor signal circuit and compare this voltage to a previously learned voltage. If the voltage measured is within the valid range, the BCM will send a class 2 message to the powertrain control module (PCM) to enable vehicle starting. If the voltage measured is not within the valid range, a class 2 message will be sent to the PCM to disable starting of the vehicle.

Read the following paragraph from GM, this will give you some insight on the passlock system on your vehicle.

The electrical switching portion of the ignition lock cylinder assembly is separate from the key and lock cylinder. The electrical switch portion and the key and lock cylinder synchronize and work in conjunction through the action of the mechanical assembly between the two components.

PASSLOCK(TM) SENSOR
The Passlock(TM) sensor contains 2 hall effect sensors. The tamper hall effect sensor is on the top. The security hall effect sensor is under the tamper hall effect sensor. Both of the hall effect sensors monitor the magnet of the lock cylinder through an opening. The tamper hall effect sensor is physically placed on top of the security hall effect sensor. This arrangement enables the tamper hall effect sensor to engage first if an intruder attempts to bypass the Passlock(TM) sensor by placing a large magnet around that area of the steering column. There is a tamper resistor inside the Passlock(TM) sensor in order to help prevent tamper to the system. Passlock(TM) equipped vehicles have a selection of 10 different security resistors ranging from 0.5K ohms up to 13.6K ohms . Installing one of the security resistors inside the Passlock(TM) sensor will generate a unique Passlock(TM) code. All 10 combinations of the Passlock(TM) sensor have the same part number.

BODY CONTROL MODULE
The body control module (BCM) contains the theft deterrent system logic. The BCM reads the Passlock(TM) data from the Passlock(TM) sensor. If the Passlock(TM) data is correct, the BCM will send a class 2 message to the PCM to enable the fuel injectors and crank relay.

During the tamper mode the vehicle may start. The vehicle will then stall. If the BCM receives the wrong Passlock(TM) data, the VTD system will immediately go into the tamper mode. The tamper mode will lock-out the vehicle fuel injectors and crank relay for 10 minutes . The SECURITY indicator will flash while the VTD is in the tamper mode.

If the Passlock(TM) sensor sends a correct password to the BCM when the ignition is in the ON position, the BCM will send a fuel enable and crank relay enable signal to the PCM.

SECURITY INDICATOR
The SECURITY indicator appears on the message center inside the instrument cluster. If the SECURITY indicator flashes or if the SECURITY indicator lights continuously during vehicle operation, refer to the system diagnosis.

POWERTRAIN CONTROL MODULE
The PCM communicates with the BCM over the Class 2 serial data line. When the BCM determines an incorrect password, it sends a Class 2 serial data password to the PCM in order to disable the crank relay and fuel injection system. If the BCM receives the expected voltage from the Passlock(TM) sensor, the BCM sends a class 2 serial data password to the PCM in order to enable the crank relay and fuel injection system. The PCM then allows the vehicle to start normally.

FUEL LOCKOUT CYCLE
The Passlock(TM) system has a lockout cycle of approximately 10 minutes . Once the vehicle is in the lockout cycle, the vehicle remains in the lockout cycle for 10 minutes , even if the ignition switch is turned from the ON position to the OFF position.

The Passlock(TM) system uses the lockout cycle in order to synchronize all of the Passlock(TM) components when any Passlock(TM) related part is replaced. The Passlock(TM) system requires 3 consecutive lockout cycles in order to complete the 30 minute learn procedure for a changed component.

CHANGING THE PASSLOCK(TM) COMPONENTS
The design of the Passlock(TM) system is to prevent theft even if the various theft deterrent parts change. The parts that can no longer be changed without the possibility of going into a tamper mode are:

* The Passlock(TM) sensor
* The BCM
* The PCM

If you replace any of these parts the vehicle may not start for 10 minutes . This is the long tamper mode. If this occurs, the system must go through a long tamper mode cycle. During this time the SECURITY indicator will be flashing for the full 10 minutes and DTC B3031 will be set. The BCM and the PCM require the full 10 minutes in order to complete a learn cycle. The ignition switch must remain in the ON position until the SECURITY indicator stops flashing. You will need to repeat the cycle if the ignition switch does not remain in the ON position. When replacing any of the above parts, perform the Programming Theft Deterrent System Components procedure.

The design of the Passlock(TM) system is to prevent the vehicle operation if the proper ignition key is not used in order to start the vehicle. The mechanical key, in normal operation, will turn the ignition lock cylinder. The Passlock(TM) sensor monitoring the position of the lock cylinder will relay the Passlock(TM) data to the body control module (BCM). The BCM will determine the validity of the Passlock(TM) data. The BCM will send a password to the powertrain control module (PCM). When the PCM receives the correct password the PCM allows the crank relay and fuel injectors to operate normally. The Passlock(TM) system requires the PCM and the BCM to communicate the various functions in order to operate. These functions transmit over the class 2 serial data line. For an explanation of the class 2 serial data description and operation refer to Data Link Communications Description and Operation in Data Link Communications.

See if the fuel pump is working. Turn the key on and listen by the gas tank if you hear the pump working. Mine was still working but didn't have enough pressure to keep the truck running. You might want to test the fuel pressure.