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For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Century (China) (CNG) 🢒 Restraints 🢒 SIR 🢒 Scan Tool Does Not Communicate with Sensing and Diagnostic Module

Object Number: 418863 Size: SF
SIR Components
SIR Schematics
SIR Caution
Handling ESD Sensitive Parts Notice

Circuit Description

The data link connector (DLC) is the provision for communicating with the inflatable restraint sensing and diagnostic module (SDM) and other Class 2 modules that are on the same data line. The DLC supplies B+ and ground to the scan tool. The scan tool is connected to the DLC in order to perform the following functions:

    • Read the data list
    • Read diagnostic trouble codes (DTCs)
    • Clear DTCs

Diagnostic Aids

The loss of serial data communication between the SDM and the instrument cluster will cause the AIR BAG warning lamp to come ON solid. Refer to Diagnostic System Check - Data Link Communications in Data Link Communications.

Test Description

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

  1. This step checks for proper operation of the scan tool.

    2.

  2. This step checks to see if the scan tool can communicate with another module on the same Class 2 data line.

    3.

  3. This step checks to see if the AIR BAG Fuse is blown.

    4.

  4. This step determines if there is a short to ground in CKT 1139 or if there is a malfunctioning SDM.

    5.

  5. This step checks to see if there an open or a high resistance in CKT 1139.

    6.

  6. This step checks to see if there is an open or a high resistance in CKT 1128.

Scan Tool Does Not Communicate With The SDM

Step

Action

Value(s)

Yes

No

1

Was the SIR Diagnostic System Check performed?

--

Go to Step 2

Go to SIR Diagnostic System Check

2

  1. Install the scan tool.
  2. Turn the ignition switch to the ON position.
  3. Turn the scan tool ON.

Does the scan tool turn ON?

--

Go to Step 3

Go to Scan Tool Inoperative in Data Link Communications

3

Attempt to establish communicaton with the powertrain control module (PCM).

Does the scan tool communicate with the PCM?

--

Go to Step 4

Go to Scan Tool Does Not Communicate w/Class 2 Data Line in Data Link Communications

4

  1. Turn the ignition switch to the OFF position.
  2. Remove the AIR BAG Fuse.
  3. Inspect the AIR BAG Fuse.

Is the AIR BAG Fuse good?

--

Go to Step 9

Go to Step 5

5
  1. Replace the AIR BAG Fuse.
  2. Turn the ignition key to the ON position and wait 10 seconds.
  3. Turn the ignition key to the OFF position.
  4. Remove the AIR BAG Fuse.
  5. Inspect the AIR BAG Fuse.

Is the AIR BAG Fuse good?

--

Go to Step 14

Go to Step 6

6

  1. Disconnect inline connectors C215 and C216.
  2. Disconnect the inflatable restraint sensing and diagnostic module. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Use the J 39200 Digital Multimeter (DMM) to measure the resistance between the output side of the AIR BAG Fuse and a known good ground.

Is the measured resistance less than the specified value?

OL

Go to Step 7

Go to Step 8

7
  1. Locate a short to ground in CKT 1139.
  2. Repair the short to ground in CKT 1139.
  3. Replace the AIR BAG Fuse.

Is the repair complete?

--

Go to Step 14

--

8
  1. Replace the inflatable restraint sensing and diagnostic module. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  2. Replace the AIR BAG Fuse.

Is the repair complete?

--

Go to Step 14

--

9

  1. Disconnect inline connectors C215 and C216.
  2. Disconnect the inflatable restraint sensing and diagnostic module. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Use the J 39200 Digital Multimeter (DMM) to measure the resistance between the output side of the AIR BAG Fuse and terminal A1 of the SDM wiring harness connector.

Is the measured resistance within the specified value?

0-2 ohms

Go to Step 11

Go to Step 10

10
  1. Locate an open or a high resistance in CKT 1139.
  2. Repair the open or the high resistance in CKT 1139.

Is the repair complete?

--

Go to Step 14

--

11

  1. Remove the scan tool.
  2. Use the J 39200 to measure the resistance between terminal F of the splice pack SP205 wiring harness connector and terminal A5 of the SDM wiring harness connector.

Is the measured resistance within the specified value?

0-5 ohms

Go to Step 13

Go to Step 12

12
  1. Inspect the splice pack SP205 and the SP205 wiring harness connector for corrosion or damaged terminals.
  2. Replace the splice pack SP205 or the SP205 wiring harness connector if either one is corroded or damaged.
  3. Locate an open or a high resistance in CKT 1128.
  4. Repair the open or the high resistance in CKT 1128.

Is the repair complete?

--

Go to Step 14

--

13

Replace the inflatable restraint sensing and diagnostic module. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Is the repair complete?

--

Go to Step 14

--

14
  1. Reconnect all SIR components.
  2. Make sure that all components and connectors are properly mounted.

Have all the SIR components been reconnected and properly mounted?

--

Go to SIR Diagnostic System Check

--