DTC P1631. Chevrolet Optra 2005

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2005 🢒 Optra 🢒 Engine 🢒 Engine Controls - 1.8L (L79) 🢒 DTC P1631

Circuit Description

The engine control module (ECM) initiates engine operation based on the immobilizer password received from the vehicle immobilizer, or vehicle theft deterrent (VTD) control module. The ignition key head contains a transponder that emits a magnetic field. This magnetic field interacts with the magnetic field generated by the coils of the theft deterrent control module creating a voltage. This voltage signal becomes the immobilizer password that is sent to the ECM. If the password is incorrect, or cannot be read by the ECM, DTC P1631 is set.

DTC Descriptors

This diagnostic procedure supports the following DTC:

DTC P1631 Invalid Data Received From Vehicle Immobilizer Control Module

Conditions for Running the DTCs

•	The ignition is ON and the engine is cranking.

•	The DTC P1631 diagnostic runs once per drive cycle.

Conditions for Setting the DTC

The ECM has received invalid data from the VTD control module

Action Taken When the DTC Sets

•	The control module stores the DTC information into memory when the diagnostic runs and fails.

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

•	The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.

•	The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC

•	A current DTC Last Test Failed clears when the diagnostic runs and passes.

•	A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.

•	Clear the DTC with a scan tool.

Diagnostic Aids

Attempting to start the vehicle by bypassing the VTD system or by substituting parts without performing the Programming Theft Deterrent System Components procedure will continue to cause a no start condition.

Step	Action	Yes	No
1	Use the scan tool in order to clear the DTCs. Turn OFF the ignition for 30 seconds. Attempt to start the engine. Use the scan tool and check for DTCs. Is DTC P1631 present?	Go to Diagnostic System Check - Theft Deterrent in Theft Deterrent	Go to Intermittent Conditions

Step

Action

Yes

Use the scan tool in order to clear the DTCs.
Turn OFF the ignition for 30 seconds.
Attempt to start the engine.
Use the scan tool and check for DTCs.

Is DTC P1631 present?

Go to Diagnostic System Check - Theft Deterrent in Theft Deterrent

Go to Intermittent Conditions