DTC 98 ONSTAR DCO Link Short to Ground. Cadillac Catera 2000

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2000 🢒 Catera 🢒 DTC 🢒 DTC 98 ONSTAR DCO Link Short to Ground

SIR Components
Power, Ground, Serial Data, Indicator and Front Inflatable Restraint Modules
Handling ESD Sensitive Parts Notice
SIR Handling Caution

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. Upon passing these tests, the energy reserve is charged and the firing transistors are tested. The SDM then goes into the CONTINUOUS MONITORING mode. The SDM is hard-wired to the body control module (BCM) through the deployment commanded output (DCO) circuit. During the CONTINUOUS MONITORING mode, the SDM sends fixed frequency pulses to the BCM. In the event of a collision involving air bag or seat belt pretensioner deployment, the SDM sends higher frequency pulses to the BCM, which in turn sends a Class 2 message to the ONSTAR module. Upon receiving the Class 2 message, the ONSTAR module transmits a deployment commanded output (DCO) signal to the service center via the vehicle's cellular telephone.

Conditions for Running the DTC

When the ignition voltage is within the normal operating voltage range and the SDM is in the CONTINUOUS MONITORING mode, the SDM monitors the DCO circuit in order to detect leakage currents to ground in the DCO circuit.

Conditions for Setting the DTC

The measured leakage current to ground is above a specified value in the DCO circuit.

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

A short to ground in the DCO circuit can cause an intermittent condition. Inspect the DCO circuit carefully for cutting and/or chafing.

Test Description

This step checks the SDM wiring harness connector.

This step checks the SDM terminals.

This step checks the BCM wiring harness connector C1.

This step checks the BCM terminals.

This step checks for a short to ground in the DCO circuit.

This step determines if there is a malfunctioning BCM or if there is a malfunctioning SDM.

Step

Action

Value(s)

Yes

Did you perform A Diagnostic System Check - SIR?

Go to Step 2

Go to Diagnostic System Check - SIR

Disconnect the inflatable restraint sensing and diagnostic and seat belt pretensioner module (SDM) wiring harness connector. Refer to Inflatable Restraint Sensing and Diagnostic and Seat Belt Pretensioner Module Replacement .
Inspect the SDM wiring harness connector for the following conditions, and Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems:

•

Corrosion

•	Damaged terminals

•	Poor connections/terminal tension

Does the SDM wiring harness connector exhibit any signs of corrosion, terminal damage, or poor connections?

Go to Step 3

Go to Step 5

Replace the SDM wiring harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 4

Inspect the SDM terminals for corrosion or damaged terminals.

Does the SDM exhibit any signs of corrosion or damaged terminals?

Go to Step 14

Go to Step 15

Inspect the SDM terminals for corrosion or damaged terminals.

Does the SDM exhibit any signs of corrosion or damaged terminals?

Go to Step 14

Go to Step 6

Disconnect the body control module (BCM) wiring harness connector C1. Refer to Body Control Module Replacement in Body Control System.
Inspect the BCM connector C1 for the following conditions, and refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems:

•

Corrosion

•	Damaged terminals

•	Poor connections/terminal tension

Does the BCM wiring harness connector C1 exhibit any signs of corrosion, terminal damage, or poor connections?

Go to Step 7

Go to Step 9

Replace the BCM wiring harness connector C1. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 8

Inspect the BCM terminals for corrosion or damaged terminals.

Does the BCM exhibit any signs of corrosion or damaged terminals?

Go to Step 13

Go to Step 15

Inspect the BCM terminals for corrosion or damaged terminals.

Does the BCM exhibit any signs of corrosion or damaged terminals?

Go to Step 13

Go to Step 10

Use the J 39200 Digital Multimeter (DMM) to measure the resistance between the DCO circuit and a known good ground.

Does the resistance measure less than the specified value?

Go to Step 11

Go to Step 12

Locate and repair a short to ground in the DCO circuit.

Did you complete the repair?

Go to Step 15

Connect the SDM wiring harness connector.
Connect the BCM wiring harness connector C1.
Turn ON the ignition, with the engine OFF.
Install a scan tool.
Use the scan tool to request the BCM Inputs.
Read the communication status of the ONSTAR test flag. Under proper operating conditions, the ONSTAR test flag will display SET.
Read the units displayed for the ONSTAR signal. Under proper operating conditions, the ONSTAR will display OK.

Does the scan tool indicate that the ONSTAR test flag displays SET and the ONSTAR signal displays OK?

Go to Step 14

Go to Step 13

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 15

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

Did you complete the replacement?

Go to Step 15

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

Did you complete the action?

Go to Diagnostic System Check - SIR