DTC P1631 Theft Deterrent Start Enable Signal Not Correct. GMC Truck Savana 1998

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1998 🢒 Savana 🢒 DTC 🢒 DTC P1631 Theft Deterrent Start Enable Signal Not Correct

Engine Controls Components
Cell 22: PWR, GND and DLC
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

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

Conditions for Setting the DTC

•	The vehicle Anti-Theft system is enabled.

•	The fuel disable is set.

•	An incorrect fuel continue password has been received.

Action Taken When the DTC Sets

•	The vehicle will not start.

•	The Malfunction Indicator Lamp (MIL) will not illuminate.

Conditions for Clearing the DTC

•	A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other emission related failure.

•	PCM battery voltage is interrupted.

•	Using a scan tool.

Test Description

Number(s) below refer to the step number(s) on the diagnostic table.

The 11 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 11 minutes has expired.

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

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

Important: Before prceeding with this table, check for any Vehicle Theft Deterrent (VTD) contoller DTCs being set (except if you were sent here from PCM replacement). If a VTD controller DTC is set, refer to the approiate VTD controller 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.

Turn the ignition on, engine off, for 11 minutes.
Turn the ignition off for 30 seconds.
Turn the ignition on, engine off, for 11 minutes.
Turn the ignition off for 30 seconds.
Turn the ignition on, engine off, for 11 minutes 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

Using a T-50/T-60 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 Vehicle Theft Deterrent (VTD) control module will be prepared for re-learn.

•	A security timer will be on for approximately 11 minutes or until DTC P1630 sets. It is important that during the 11 minute-wait, the user keep the terminal connected to the vehicle.

•	When the PCM and the Vehicle Theft Deterrent (VTD) 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 Tech 2 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 Tech 2 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 Tech 2.
Return the Scan Tool to the vehicle and connect to Diagnostic Link Connector (DLC).
Select Service Programming from the Tech 2 main menu. Answer the prompts regarding the model year and vehicle type. Press the Theft Re-learn soft key on the Tech 2.
Follow the instructions on the remaining screens.

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

•	A security timer will be on for approximately 11 minutes or until DTC P1630 sets. It is important that during the 11 minute-wait, the user keep the terminal connected to the vehicle.

•	When the PCM and the VTD 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 table

Go to Step 2