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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Corvette 🢒 Restraints 🢒 SIR 🢒 Scan Tool Does Not Communicate with Sensing and Diagnostic Module

Object Number: 391019 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 is located under the LH side of the instrument panel. The DLC supplies B+ and ground to the scan tool. The scan tool communicates with the SDM and other Class 2 modules that are on the data line.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 stay ON. Refer to Diagnostic System Check - Data Link Communications in Data Link Communications.

Test Description

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

    2.

  2. This test checks for scan tool communication with the PCM.

    3.

  3. This test checks for a blown SDM Fuse.

    4.

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

    5.

  5. This test checks for an open or high resistance condition in CKT 1139.

    6.

  6. This test determines whether there is an open or high resistance in CKT 1128 or if the SDM is malfunctioning.

Scan Tool Does Not Communicate with 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 on the scan tool.

Does the scan tool power-up?

--

Go to Step 3

Go to Scan Tool Inoperative in Data Link Communications

3

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

Can the scan tool communicate with the PCM?

--

Go to Step 4

Go to Scan Tool Does Not Communicate with Components in Data Link Communications

4

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

Is the SDM Fuse good?

--

Go to Step 9

Go to Step 5

5
  1. Replace the SDM fuse.
  2. Turn the ignition switch to the ON position for 10 seconds.
  3. Turn the ignition switch to the OFF position.
  4. Inspect the SDM Fuse.

Is the SDM Fuse good?

--

Go to Step 14

Go to Step 6

6

  1. Disconnect inline connectors C211 and C213.
  2. Disconnect the inflatable restraint sensing and diagnostic module (SDM). 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 SDM Fuse and ground.

Is the resistance reading less than the specified value?

OL

Go to Step 7

Go to Step 8

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

Is the repair complete?

--

Go to Step 14

--

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

Is the repair complete?

--

Go to Step 14

--

9

  1. Disconnect inline connectors C211 and C213.
  2. Disconnect the inflatable restraint sensing and diagnostic module (SDM). 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 SDM Fuse and terminal A1 of the SDM wiring harness connector.

Is the resistance reading 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. Disconnect the scan tool from the data link connector (DLC).
  2. Use the J 39200 DMM to measure the resistance from the SDM wiring harness connector terminal A4 to the DLC terminal 2.

Is the resistance reading within the specified value?

0-5 ohms

Go to Step 13

Go to Step 12

12
  1. Locate an open or a high resistance in CKT 1128.
  2. 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 (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Is the repair complete?

--

Go to Step 14

--

14

Reconnect all the SIR system components, make sure all the components are properly mounted.

Have all the SIR components been reconnected and properly mounted?

--

Go to SIR Diagnostic System Check

--