2000 pont. g/p int. start/stall. replaced theft module twice,comp., ig.swicht,keys,P1629

Your Rendezvous has GM PasskeyIII

"When trying to start the vehicle if the engine does not
start and the SECURITY message comes on, the
key may have a damaged transponder. Turn the ignition off and try again."

So if the SECURITY is showing on message center then the key is not recognized and you will need to try a different transponder key.

If SECURITY is not showing, then set the emergency brake and move transmission selector to N(uetral), keep foot on brake and try to start.

P1629
Theft Deterrent Fuel Enable Signal Not Received
ECM, PCM
DTC P1629 in Theft Deterrent


Does the vehicle start and run ?

P1629 obdII code.
THEFT DETERRENT CRANK SIGNAL MALFUNCTION

Vehicle operation is disabled if incorrect key or starting procedure is used.

Read more at the link below.

P1629 GM Forum Buick Cadillac Chev Olds GMC Pontiac chat

Without a key with anti-theft transponder inside your not starting anything . Your best bet call mobile lock smith . Anti-theft system ,software programmed into all module's involved in starting the vehicle .
The vehicle theft deterrent (VTD) system functions are provided by the theft deterrent control module. The VTD system prevents vehicle operation if a learned Passkey III (PK3) ignition key is not used to start the vehicle. Vehicles with steering column mounted ignition switches have the exciter integral with the theft deterrent control module which is located within the steering column. Vehicles with instrument panel mounted ignition switches have exciter modules separate from the theft deterrent control module with the vehicle wiring harness connecting the two. The PK3 key has a transponder embedded in the plastic head of the key. The exciter is an antenna which is made up of wire coils which surround the ignition lock cylinder. The PCM enables engine starting when it receives a learned fuel enable signal from the theft deterrent control module. The components of the VTD system are as follows:

U0140 Chevrolet Lost Communication With Body Control Module P1629 Chevrolet Theft Deterrent Start Enable Signal Not Received http://www.carobdcode.com/u0422-gmc-invalid-data-received-from-body-control-module#.Vva4p8vmqQw

DTC P0633 : Theft Deterrent Key Not Programmed

When learning the pre-release password, as well as the challenge and response sequence, the engine control module (ECM) is placed in learn mode. DTC P0633 will set automatically as an indicator that the system is in learn mode and not as a fault indicator. Once the password and challenge/response are learned, learn mode will be exited when the engine is successfully started. At this point, the DTC will be cleared. If the ECM does not exit learn mode, P0633 will remain current and indicate a fault.
The "key" referenced in the DTC descriptor does not refer to the vehicle key. In this case, "key" is referring to the challenge response.
DTC P0633 requires a successful engine start to exit the learn procedure and clear the DTC. If an unrelated malfunction exists that causes engine starting to be disabled or otherwise unavailable, learn mode will not exit and DTC P0633 will remain current. In this situation, the cause of the inoperative engine starting must be corrected before diagnosing DTC P0633.
DTC P1629: Theft Deterrent Fuel Enable Signal Not Received
The theft deterrent module (TDM) sends the pre-release password to the engine control module (ECM) via the serial data circuit. The ECM then sends a challenge to the TDM. Both the ECM and TDM perform a calculation on this challenge. If the calculated response from the TDM equals the calculation performed by the ECM, the ECM will allow vehicle starting.
DTC P1629 is an indicator that the challenge response was not received within the required 2 second window. This does not necessarily indicate a fault is present with the TDM or ECM. Factors such as a long engine crank, a delay in the serial data communication, or B-codes set in the TDM will cause DTC P1629 to set. This DTC should not be used as a fault indicator, but rather as a symptom to assist in the diagnosis of these other systems.
Who checked the codes , you -dealer ? You need to have BCM checked for codes B - codes ! you need a up scale diagnostic scan tool for that , dealer Tech -2 !
DTC B3935 57 : Transponder Authentication Error
DTC B3976 46 : Unconfigured Transponder/Vehicle Configuration Not Programmed
DTC B3060 : Unprogrammed Transponder Identification Code Received
DTC B3055: No Transponder Modulation or No Transponder
DTC B3031: Security System Controller In Learn Mode

its the ignition lock the contacts are worn and is not reading the key

STARTING DISABLED REMOVE KEY
Refer to Theft Systems Description and Operation in Theft Deterrent

STARTING DISABLED REMOVE KEY
The radio illuminates the STARTING DISABLED REMOVE KEY message when the VTD system has disabled the starting system. The radio receives a message from the theft deterrent control module via the serial data circuit requesting illumination.

Your best bet ,take it to Cadillac dealer and have it checked . Could have DTC'S - diagnostic trouble codes
DTC B1015
DTC B1016
DTC B3031
DTC B3055
DTC B3060
DTC B3090
DTC B3935
DTC B3976
DTC P1629
DTC P1630
DTC P1631

The theft deterrent module or the insturment cluster or the ECM is not seeing correct info.
The vehicle theft deterrent (VTD) system functions are provided by the theft deterrent control module. When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, the transponder embedded in the head of the key is energized by the exciter coils surrounding the ignition lock cylinder. The energized transponder transmits a signal that contains its unique value, which is received by the theft deterrent control module. The theft deterrent control module then compares this value to a value stored in memory, learned key code. If the value is correct the theft deterrent control module sends a random generated number to the transponder, this is called a challenge. Both the transponder and the theft deterrent control module perform a calculation on the challenge, if the calculations match the theft deterrent control module sends the fuel continue password via the serial data circuit to the Engine control module (ECM). If either the transponders unique value or the calculation to the challenge is incorrect the theft deterrent control module will send the fuel disable password to the ECM via the serial data circuit. The components of the VTD system are as follows:
• Theft deterrent control module
• Engine control module (ECM)
• Ignition key (Transponder)
• Ignition lock cylinder
• Security indicator

try leaving the key on for 5 to 10 minutes
for the BCM (body control module) to relearn

power locks check fuse and relay.take car to dearlership.they have to check your theft deterrent module.when its in security mode.your problem could be it cant read the chip on ignition keys or the theft deterrent module is failing.not a home fix.