GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 Catera 🢒 DTC 🢒 DTC 78 Driver Side Air Bag Deploy Loop Resist. Low

Object Number: 601086 Size: SF
SIR Components
Seat Belt Pretensioners, Side Inflatable Restraint Modules, and Sensors
SIR Handling Caution
Handling ESD Sensitive Parts Notice

Circuit Description

When you first turn ON the ignition, the inflatable restraint sensing and diagnostic and seat belt pretensioner module (SDM) performs tests to diagnose critical malfunctions within itself. Then, the SDM proceeds with the RESISTANCE MEASUREMENT test to measure the deployment loop resistances to ensure that they are within their respective normal resistance ranges. During one portion of the RESISTANCE MEASUREMENT test, the SDM does the following:

    • Measures the voltage difference between the driver side high and driver side low circuits
    • Uses the measured voltage to calculate the resistance of the driver side air bag deployment loop

Upon passing these tests, the energy reserve is charged and the firing transistors are tested. The SDM then goes into the CONTINUOUS MONITORING mode.

Conditions for Running the DTC

When the ignition voltage is within the normal operating voltage range, the SDM performs the RESISTANCE MEASUREMENT test in order to calculate the resistance of the driver side air bag deployment loop.

Conditions for Setting the DTC

The calculated resistance of the driver side air bag deployment loop is below 1.6 ohms.

Action Taken When the DTC Sets

The SDM turns ON the AIR BAG warning lamp.

Conditions for Clearing the DTC
    • You can issue a CLEAR CODES command
    • A history DTC will clear once 255 malfunction free ignition cycles have occurred.

Diagnostic Aids

The following can cause an intermittent condition:

    • The inflatable restraint side impact module 2-way connector.
    • The SDM wiring harness connector.
    • The wire to terminal connections in the driver side high circuit.
    • The wire to terminal connections in the driver side low circuit.
    • Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The numbers below refer to step numbers on the diagnostic table.

  1. This step checks the inflatable restraint side impact module 2-way connector.

    2.

  2. This step checks the SDM wiring harness connector.

    3.

  3. This step determines if there is a short between the driver side high and driver side low circuits or if there is a malfunctioning SDM.

Step

Action

Value(s)

Yes

No

1

Did you perform A Diagnostic System Check - SIR?

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Go to Step 2

Go to Diagnostic System Check - SIR

2

  1. Turn OFF the ignition.
  2. Remove the ignition key.
  3. Disconnect the inflatable restraint side impact module 2-way connector. Refer to Inflatable Restraint Side Impact Module Replacement - Left Side .
  4. Inspect the male and female sides of the inline connector for the following conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems:
    5. • Corrosion
    • Damaged terminals
    • Poor connections/terminal tension

Does either the male or female sides of the inline connector exhibit signs or corrosion, terminal damage, or poor connections?

--

Go to Step 3

Go to Step 4

3
  1. If the female side of the inline connector is damaged, the inflatable restraint side impact module must be replaced.
  2. If the male side of the inline connector is damaged, replace the male side of the connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 10

--

4
  1. Reconnect the inflatable restraint side impact module 2-way 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 this DTC is current?

--

Go to Step 5

Go to Diagnostic Aids

5
  1. Turn OFF the ignition.
  2. Remove the ignition key.
  3. Use the J 38715-55 adapter to connect the J 38715-A SIR Driver/Passenger Load Tool PASSENGER INFLATOR connector to the inflatable restraint side impact module wiring harness connector.
  4. Turn ON the ignition, with the engine OFF.
  5. Use the scan tool to request the SIR data list display.
  6. Read the driver side air bag deployment loop resistance LH SIDE AIR BAG RES.

Does the scan tool indicate that the LH SIDE AIR BAG RES. is less than the specified value?

1.6 ohms

Go to Step 7

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Remove the ignition key.
  3. Replace the inflatable restraint side impact module. Refer to Inflatable Restraint Side Impact Module Replacement - Left Side .

Did you complete the replacement?

--

Go to Step 10

--

7

  1. Turn OFF the ignition.
  2. Remove the ignition key.
  3. Remove the J 38715-A .
  4. Disconnect the inflatable restraint sensing and diagnostic and seat belt pretensioner module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic and Seat Belt Pretensioner Module Replacement .
  5. Insert the J 42113 Shorting Bar Tool into the SDM wiring harness connector above the driver side high and driver side low circuits.
  6. Use the J 39200 Digital Multimeter (DMM) to measure the resistance between the driver side high and driver side low circuits.

Does the resistance measure less than the specified value?

OL

Go to Step 8

Go to Step 9

8

Locate and repair a short between the driver side high and driver side low circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 10

--

9

Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic and Seat Belt Pretensioner Module Replacement .

Did you complete the repair?

--

Go to Step 10

--

10
  1. Reconnect all SIR components.
  2. Verify that all components and connectors are properly mounted.
  3. Turn ON the ignition, with the engine OFF.
  4. Use the scan tool in order to clear the DTCs.

Did you complete the action?

--

Go to Diagnostic System Check - SIR

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