codes b2721 p1631!!!!!!!!!???????????
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Cruising
Joined: Jan 2009
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codes b2721 p1631!!!!!!!!!???????????
having int start problems have codes b2721 and p1631. if it doesnt start i can wait 3 mins and it will start. i have tried the relearn no luck please anybody ever had this problem maybe had ideas what i could try
Melting Slicks
Joined: Oct 2007
Posts: 2,383
Likes: 13
From: Kinston North Carolina
Read this.
DTC B2721
Circuit Description
The body control module (BCM) supplies a 5 volt signal and a ground circuit for the PASS-Key® system. This allows the BCM to detect PASS-Key® resistance values. Inserting the PASS-Key® (with resistor pellet) in the ignition lock cylinder completes the PASS-Key® circuit. Contacts in the ignition lock cylinder mate with the pellet contacts. The BCM compares the resistance value of the key pellet to the valid resistance programmed into the BCM. If the proper resistance value is read, the BCM allows the following functions to occur:
The theft deterrent relay to energize.
The steering column to unlock.
The BCM sends a message through the serial data line to the powertrain control module (PCM) to enable fuel delivery.
If the resistance value is incorrect, a malfunction is present and a DTC will set.
Conditions for Setting the DTC
The resistance level sampled at the BCMs PASS-Key® signal circuit is one of 15 valid but incorrect resistance ranges, signaling an invalid PASS-Key® detection.
This condition must be present for 1 second.
Action Taken When the DTC Sets
The BCM stores DTC B2721 in memory.
The BCM sends a message to the instrument panel cluster (IPC) to illuminate the SECURITY indicator.
The BCM will disable the theft deterrent relay.
The PCM will not allow fuel delivery to occur.
The BCM disables sampling of the PASS-Key® resistance for a time-out period of 3 minutes.
The steering column remains in the locked position.
Conditions for Clearing the DTC
This DTC requires an ignition cycle in order to change from current to history.
The BCM detects a valid PASS-Key® resistance value on the PASS-Key® signal circuit after the 3 minute time-out period occurs.
A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.
Use the IPC clearing DTCs feature.
Use a scan tool.
Diagnostic Aids
The following conditions may cause an intermittent malfunction:
There is an intermittent open or short to ground on the PASS-Key® signal or ground circuit.
There are poor connections at the BCM or the ignition switch connector.
The ignition lock cylinder key contacts or the PASS-Key® resistor is dirty or loose.
If the key resistor pellet is incorrect, there will be no BCM outputs to the theft deterrent relay or to the PCM. This state will last about 3 minutes. If a key is inserted, or the ignition is turned ON again before the 3 minute time frame is complete, the timer will reset to 3 minutes. Disconnecting the battery will not clear the timer sequence, but the timer will reset to 3 minutes when the battery power is restored. Even if a proper key is inserted during one of the time periods, the vehicle will not start until the total time period has elapsed.
DTC P1631
Circuit Description
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.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The PCM detects an incorrect password from the VTD system.
The condition is present for less than 1 second.
Action Taken When the DTC Sets
The body control module (BCM) send a class to message to the instrument panel cluster (IPC) to illuminate the SECURITY indicator.
The PCM will not illuminate the malfunction indicator lamp (MIL).
The PCM will store conditions which were present when the DTC set as Failure Records data only. This information will not be stored as Freeze Frame data.
Conditions for Clearing the MIL/DTC
A History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
The DTC can be cleared by using a scan tool.
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 an incorrect key is used when attempting to start the vehicle, or 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.
DTC B2721
Circuit Description
The body control module (BCM) supplies a 5 volt signal and a ground circuit for the PASS-Key® system. This allows the BCM to detect PASS-Key® resistance values. Inserting the PASS-Key® (with resistor pellet) in the ignition lock cylinder completes the PASS-Key® circuit. Contacts in the ignition lock cylinder mate with the pellet contacts. The BCM compares the resistance value of the key pellet to the valid resistance programmed into the BCM. If the proper resistance value is read, the BCM allows the following functions to occur:
The theft deterrent relay to energize.
The steering column to unlock.
The BCM sends a message through the serial data line to the powertrain control module (PCM) to enable fuel delivery.
If the resistance value is incorrect, a malfunction is present and a DTC will set.
Conditions for Setting the DTC
The resistance level sampled at the BCMs PASS-Key® signal circuit is one of 15 valid but incorrect resistance ranges, signaling an invalid PASS-Key® detection.
This condition must be present for 1 second.
Action Taken When the DTC Sets
The BCM stores DTC B2721 in memory.
The BCM sends a message to the instrument panel cluster (IPC) to illuminate the SECURITY indicator.
The BCM will disable the theft deterrent relay.
The PCM will not allow fuel delivery to occur.
The BCM disables sampling of the PASS-Key® resistance for a time-out period of 3 minutes.
The steering column remains in the locked position.
Conditions for Clearing the DTC
This DTC requires an ignition cycle in order to change from current to history.
The BCM detects a valid PASS-Key® resistance value on the PASS-Key® signal circuit after the 3 minute time-out period occurs.
A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.
Use the IPC clearing DTCs feature.
Use a scan tool.
Diagnostic Aids
The following conditions may cause an intermittent malfunction:
There is an intermittent open or short to ground on the PASS-Key® signal or ground circuit.
There are poor connections at the BCM or the ignition switch connector.
The ignition lock cylinder key contacts or the PASS-Key® resistor is dirty or loose.
If the key resistor pellet is incorrect, there will be no BCM outputs to the theft deterrent relay or to the PCM. This state will last about 3 minutes. If a key is inserted, or the ignition is turned ON again before the 3 minute time frame is complete, the timer will reset to 3 minutes. Disconnecting the battery will not clear the timer sequence, but the timer will reset to 3 minutes when the battery power is restored. Even if a proper key is inserted during one of the time periods, the vehicle will not start until the total time period has elapsed.
DTC P1631
Circuit Description
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.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The PCM detects an incorrect password from the VTD system.
The condition is present for less than 1 second.
Action Taken When the DTC Sets
The body control module (BCM) send a class to message to the instrument panel cluster (IPC) to illuminate the SECURITY indicator.
The PCM will not illuminate the malfunction indicator lamp (MIL).
The PCM will store conditions which were present when the DTC set as Failure Records data only. This information will not be stored as Freeze Frame data.
Conditions for Clearing the MIL/DTC
A History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
The DTC can be cleared by using a scan tool.
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 an incorrect key is used when attempting to start the vehicle, or 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.
Last edited by byronhunter; May 28, 2009 at 07:25 PM.
