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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Astro - 4WD 🢒 Restraints 🢒 SIR 🢒 DTC B0018 RF/Passenger Frontal Deployment Loop (Single Stage or Stage 1) Short to Ground/Voltage Out of Range

Object Number: 572350 Size: SF
SIR Components
SIR Schematics
SIR Handling Caution
Handling ESD Sensitive Parts Notice
SIR Caution

Circuit Description

When you first turn the ignition switch to the RUN position, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. The SDM then performs the following continuous diagnostic tests on the deployment loops:

    • Deployment loop voltage out of range test
    • Deployment loop resistance measurement test

If the voltage out of range test detects a short to voltage condition, the resistance measurement test for that deployment loop will not be performed.

Conditions for Running the DTC
    • Ignition 1 voltage is within the normal operating range.
    • Passenger frontal deployment loop is not shorted to voltage.

Conditions for Setting the DTC
    • The SDM detects the voltage at passenger frontal high is greater than 6 volts for 300 milliseconds.
    • The SDM detects the voltage at passenger frontal high is less than 2.4 volts and passenger frontal high to low side resistance is less than 6 ohms for 300 milliseconds.

Action Taken When the DTC Sets
    • The SDM disables the passenger frontal deployment resistance test.
    • The SDM commands ON the AIR BAG warning lamp via Class 2 serial data.

The SDM also sets this DTC as current after an accident. The SDM will write the status of this DTC to the "crash log" area of the EEPROM for retrieval.

Conditions for Clearing the DTC
    • Passenger frontal high is 6 volts or less for 300 milliseconds.
    • Passenger frontal high is 2.4 volts or greater and passenger frontal high to low side resistance is less than 6 ohms for 300 milliseconds.
    • You issue a scan tool CLEAR CODES command.
    • A history DTC will clear once 255 malfunction free ignition cycles have occurred.

When the SDM detects that no DTCs are present, the SDM commands the AIR BAG warning lamp OFF.

Diagnostic Aids

The following can cause an intermittent condition:

    • A short between the passenger frontal high and the passenger frontal low circuits.
    • A malfunctioning shorting bar on the inflatable restraint IP module 2-way connector.
    • Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. This step inspects the inflatable restraint IP module in-line connector.

    2.

  2. Tests for a malfunctioning inflatable restraint IP module.

    3.

  3. Tests for a short to ground in the passenger frontal high deployment circuit.

    4.

  4. Tests for a short to ground in the passenger frontal low deployment circuit.

    5.

  5. Tests for a short to voltage in the passenger frontal high deployment circuit.

    6.

  6. Tests for a short to voltage in the passenger frontal low deployment circuit or if there is a malfunctioning SDM.

Step

Action

Value(s)

Yes

No

1

Did you perform the SIR Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - SIR

2

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint IP module in-line connector.
  3. Inspect the wiring harness in-line connector for the following conditions:
    4. • Corrosion
    • Terminal damage
    • Poor connections/terminal tension

Do the connectors exhibit any signs of corrosion, terminal damage, or poor connections?

--

Go to Step 3

Go to Step 4

3

Replace the wiring harness side of the in-line connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you complete the replacement?

--

Go to Step 16

--

4
  1. Reconnect the inflatable restraint IP module in-line connector.
  2. Verify that the connector position assurance (CPA) is properly installed.
  3. Turn ON the ignition, with the engine OFF.
  4. Use the scan tool to request the SIR DTC display.

Does the scan tool indicate that DTC B0018 is current?

--

Go to Step 5

Go to Diagnostic Aids

5

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint IP module in-line connector.
  3. Install the J 38715-A SIR Load Tool to the wiring harness side of in-line connector. Use appropriate connector adaptors where necessary.
  4. Turn ON the ignition, with the engine OFF.
  5. Use scan tool to request the SIR DTC display.

Does the scan tool indicate that DTC B0018 is current?

--

Go to Step 7

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Replace the inflatable restraint IP module. Refer to Inflatable Restraint Instrument Panel Module Replacement .

Did you complete the replacement?

--

Go to Step 16

--

7

  1. Turn OFF the ignition.
  2. Remove the J 38715-A SIR Load Tool.
  3. Disconnect the inflatable restraint sensing and diagnostic module (SDM) connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  4. Using J 39200 DMM measure the resistance between the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector passenger frontal high deployment circuit terminal and a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure less than the specified value?

OL

Go to Step 8

Go to Step 9

8

Locate and repair a short to ground in the passenger frontal high deployment circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

9

Using J 39200 DMM measure the resistance between the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector passenger frontal low deployment circuit terminal and a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure less than the specified value?

OL

Go to Step 10

Go to Step 11

10

Locate and repair a short to ground in the passenger frontal low deployment circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

11

  1. Turn ON the ignition, with the engine OFF.
  2. Using J 39200 DMM measure the voltage between the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector passenger frontal high deployment circuit terminal and a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the voltage measure less than the specified value?

1 V

Go to Step 13

Go to Step 12

12

Locate and repair a short to voltage in the passenger frontal high deployment circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

13

Using J 39200 DMM measure the voltage between the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector passenger frontal low deployment circuit terminal and a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the voltage measure less than the specified value?

1 V

Go to Step 15

Go to Step 14

14

Locate and repair a short to voltage in the passenger frontal low deployment circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

15
  1. Turn OFF the ignition.
  2. Replace the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Did you complete the replacement?

--

Go to Step 16

--

16
  1. Reconnect all SIR system components.
  2. Verify that all components, connectors and CPAs are properly mounted.
  3. Use the scan tool in order to clear the DTCs.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK