DTC P1631 Theft Deterrent Start Enable Signal Not Correct. GMC Truck GMC C Pickup

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2000 🢒 GMC C Pickup - 2WD 🢒 Engine 🢒 Engine Controls - 6.5L (L65) 🢒 DTC P1631 Theft Deterrent Start Enable Signal Not Correct

Engine Controls Components
PCM Power, Grounding, MIL and DLC
Handling ESD Sensitive Parts Notice
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

This test checks for mismatched (incorrect) passwords between the Passlock module and PCM. Whenever the Passlock module or PCM are replaced, a theft learn procedure must be followed in order for the new password to be learned.

Conditions for Running the DTC

The ignition switch in the ON position.

Conditions for Setting the DTC

An incorrect fuel continue password has been received from the Passlock module.

Action Taken When the DTC Sets

•	The VTD system is enabled.

•	The vehicle will not start.

•	The malfunction indicator lamp (MIL) will not illuminate.

Conditions for Clearing the DTC

•	A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.

•	The use of a scan tool.

Diagnostic Aids

Refer to Theft Deterrent for further diagnosis.

Test Description

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

The 10 minute and 30 second time criteria, are a minimum required amount of time. The time limit can exceed this limit, without interfering with the Auto Learn Procedure. A scan tool can be used (VTD Auto Learn Timer equals Inactive) to determine when the 10 minutes has expired.

The security lamp will remain ON until 10 minute timer is complete. Depending on the component replaced, the lamp may remain ON steady or flash.

If DTC P1631 is set, indicates that the procedure was not followed correctly. The Re-learn procedure will have to be re-performed.

Step

Action

Values

Yes

Important: Before clearing DTCs use the scan tool Capture Info to record freeze frame and failure records for reference, as data will be lost when clear Info function is used.

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

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Important: Before proceeding with this table, check for any Vehicle Theft Deterrent (VTD) DTCs being set (except if you were sent here from PCM replacement). If VTD DTCs are set, refer to the appropriate DTC.

Is a T-50/T-60 available?

Go to Step 5

Go to Step 3

Is a Tech 2 available?

Go to Step 6

Go to Step 4

Important:: While the PCM is in the Auto Learn Procedure, battery voltage must be maintained at all times. This procedure must be followed exactly as indicated or the procedure will have to be repeated from the beginning.

Important: Performing the following procedures will cause a DTC P1630 to set when they are completed. This is the intended functionality. Once it is set, turn the ignition off for 30 seconds, then turn the ignition back on and P1630 will clear. If it does not, go to DTC P1630 table.

Attempt to start vehicle (vehicle will start and stall), after the engine has stalled leave the ignition ON for 10 minutes (security light will remain on for 10 minutes and then go out).
After the Security lamp turns OFF, turn the ignition off for 30 seconds.
Again, attempt to start vehicle (vehicle will start and stall), after the engine has stalled leave the ignition ON for 10 minutes (security light will remain on for 10 minutes and then go out).
After the Security lamp turns OFF, turn the ignition off for 30 seconds.
Again, attempt to start vehicle (vehicle will start and stall), after the engine has stalled leave the ignition ON for 10 minutes (security light will remain on for 10 minutes and then go out) or until DTC P1630 sets.
Turn the ignition off for 30 seconds.
Turn the ignition on and wait 30 seconds.
Attempt to start the engine.

Does the engine start and operate normally?

Go to Step 7

Go to Step 8

Important: Performing the following procedures will cause a DTC P1630 to set when they are completed. This is the intended functionality. Once it is set, turn the ignition off for 30 seconds, then turn the ignition back on and DTC P1630 will clear. If it does not, go to DTC P1630 table.

Using Techline terminal, enter the Service Programming System (SPS).
Select terminal to vehicle programming.
Select Done and follow instructions on Vehicle Set-up screen
Select Vehicle Theft Re-learn.
Follow the instructions on the remaining screens.

•	The PCM and the Passlock control module will be prepared for a re-learn.

•	A security timer will be on for approximately 10 minutes or until DTC P1630 sets. It is important that during the 10 minute-wait, the user keep the terminal connected to the vehicle.

•	When the PCM and the Passlock control module are prepared to re-learn, turn the ignition OFF for 30 seconds and then start the engine.

Does the engine start and operate normally?

Go to Step 7

Go to Step 8

Using a scan tool enter the Service Programming System (SPS).
After entering the vehicle information, choose the Request Info soft key on the scan tool.
Select Done and follow instructions on Vehicle Set-up screen.
Disconnect the scan tool from the vehicle and connect to the Techline terminal.
At the Techline terminal select Service Programming System (SPS) and select terminal to scan tool programming method. Select Done.
Follow the instructions on the remaining screens.
Select Vehicle Theft Re-learn.
Select Program at the summary screen. The terminal will download information to the scan tool.
Return the scan tool to the vehicle and connect to Diagnostic Link Connector (DLC).
Select Service Programming from the scan tool main menu. Answer the prompts regarding the model year and vehicle type. Press the Theft Re-learn soft key on the scan tool.
Follow the instructions on the remaining screens.

•	The PCM and the Passlock control module will be prepared for re-learn.

•	A security timer will be on for approximately 10 minutes or until DTC P1630 sets. It is important that during the 10 minute-wait, the user keep the terminal connected to the vehicle.

•	When the PCM and the Passlock control module are prepared to re-learn, turn the ignition OFF for 30 seconds and then start the engine.

Does the engine start and operate normally?

Go to Step 7

Go to Step 8

Important:: Before Clearing DTCs, monitor all DTC status parameters and note any additional DTCs.

Clear PCM DTCs.
Turn the ignition OFF for 30 seconds.
Attempt to start the engine.

Does the engine start and operate normally?

System OK

Go to Step 8

Are DTCs P1626, P1630 or P1631 set?

Go to applicable DTC

Go to Step 2