GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Astro - 2WD 🢒 Body and Accessories 🢒 Theft Deterrent 🢒 SECURITY Indicator Always On or Flashing

Object Number: 381516 Size: LF
Theft Deterrent System Components
Theft Deterrent System Schematics
Ignition Switch, Run, Run/Start, Off/Run/Start Bus
B+ Bus
B+ Bus
Cell 81 Instrument Cluster with Gauges (2 of 5)
GAUGES, AIR BAG Fuses
STOP/HAZ, AUX PWR Fuses
Cell 50 Data Link Connector Pin Assignment
Cell 14 Ground Distribution (5 of 10)
Cell 14 Ground Distribution (4 of 10)
Theft Deterrent System Schematic Icons
Theft Deterrent System Schematic Icons
Theft Deterrent System Schematic Icons

Circuit Description

The Security Indicator Always On or Flashing check is designed to find out the reason the Security indicator is staying on or flashing. However, the Theft Deterrent System Diagnostic System Check must always be the starting point for all Passlock system troubleshooting.

The Diagnostics in this table are designed to troubleshoot non DTC troubles. For example Battery power, Ignition 1 input, and shorted or open SECURITY indicator circuit.

Diagnostic Aids
    • Perform a visual check of the wiring and connectors.
    • Refer to Intermittents and Poor Connections

Test Description

The numbers below refer to the numbers in the diagnostic table.

  1. This step will determine if the Passlock module or the harness is causing the Security Indicator to stay on.

    2.

  2. This step determines if there is a short to ground in CKT 749.

  3. This step tests for an open in the class 2 line between Passlock terminal B4 and Splice S233.

    4.

  4. This step verifies if the security fuse randomly opened.

    5.

  5. This step tests for a short to ground in CKT 1740.

    6.

  6. This step tests for Ignition voltage at B3

    7.

  7. This step tests for battery input to the Passlock module.

Step

Action

Value(s)

Yes

No

1

Did you perform the Passlock System Check?

--

Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

2

Did the SECURITY telltale turn on with the ignition off?

--

Go to Step 16

Go to Step 3

3
  1. Turn the ignition switch to the LOCK position.
  2. Disconnect the Passlock module. Refer to Theft Deterrent Module Replacement .
  3. Turn the ignition switch to the ON position.

Did the security indicator turn off?

--

Go to Step 6

Go to Step 4

4
  1. Disconnect the Instrument Cluster connector. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console.
  2. Using the J 39200 , measure the resistance from connector terminal B2 of the Passlock module to ground.

Is the resistance within the specified value?

OL (Infinite)

Go to Step 18

Go to Step 5

5

Repair the short to ground in circuit 749.

Is the repair complete?

--

Go to Diagnostic System Check - Theft Deterrent

--

6

Using the J 39200 , measure the resistance from connector terminal B4 of the Passlock module to connector terminal 2 of the data link connector (DLC).

Is the resistance within the specified value?

0-5  ohms

Go to Step 8

Go to Step 7

7

Repair the open in circuit 1807 between Splice S233 and terminal B4 of the Passlock module.

Is the repair complete?

--

Go to Diagnostic System Check - Theft Deterrent

--

8

Test the Security Fuse.

Is the Security fuse open?

--

Go to Step 9

Go to Step  12

9
  1. Turn the ignition switch to the OFF position.
  2. Reconnect the Passlock module.
  3. Replace the Security fuse.
  4. Turn the Ignition switch to the ON position.

Is the Security fuse open?

--

Go to Step 10

Go to Diagnostic System Check - Theft Deterrent

10
  1. Turn the Ignition switch to the OFF position.
  2. Disconnect the Passlock module connector. Refer to Theft Deterrent Module Replacement .
  3. Using the J 39200 , measure the resistance from connector terminal B8 of the Passlock module to ground.

Is the resistance within the specified value?

OL (Infinite)

Go to Step  17

Go to Step 11

11
  1. Repair the short to ground in circuit 1740.
  2. Replace the Security fuse.

Is the repair complete?

--

Go to Diagnostic System Check - Theft Deterrent

--

12

Using the J 39200 , measure the voltage from connector terminal B3 of the Passlock module to ground.

Is the voltage within the specified value?

9-16  V

Go to Step 14

Go to Step 13

13

Repair the open in circuit 39 between S213 and connector terminal B3 of the Passlock module.

Is the repair complete?

--

Go to Diagnostic System Check - Theft Deterrent

--

14

Using the J 39200 , measure the voltage from connector terminal B8 of the Passlock Module to ground.

Is the voltage within the specified value?

9-16 V

Go to Step 17

Go to Step 15

15

Repair the open in circuit 1740.

Is the repair complete?

--

Go to Diagnostic System Check - Theft Deterrent

--

16

Repair the short to battery in circuit 749.

Is the repair complete?

--

Go to Step 17

--

17

Replace the Passlock module. Refer to Theft Deterrent Module Replacement .

Is the repair complete?

--

Go to Step 19

--

18

Replace the Instrument Cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console.

Is the repair complete?

--

Go to Diagnostic System Check - Theft Deterrent

--

19
  1. Reconnect all previously disconnected connectors and components.
  2. Ensure that the ignition switch is in the ON position.
  3. Replace any open fuses.
  4. Connect the scan tool.
  5. Clear Passlock DTCs, if any.
  6. Perform one of the following Passlock reprogramming procedures:
    7. • Seed and Key (10 minutes) Refer to PASSLOCK Reprogramming Seed and Key .
    • Auto learn (30 minutes) Refer to PASSLOCK Reprogramming Auto Learn .

Is the repair complete?

--

Go to Diagnostic System Check - Theft Deterrent

--