Content .. 2062 2063 2064 2065 ..

Hummer H2. Manual - part 2064

SYMPTOMS - SIR

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the SIR system. Refer to Checking
Aftermarket Accessories in Wiring Systems.

Inspect the easily accessible or visible system components for obvious damage or conditions which could
cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for
Intermittent Conditions and Poor Connections in Wiring Systems.

Symptom List

Refer to Air Bag Indicator Circuit Malfunction in order to diagnose the symptom.

AIR BAG INDICATOR CIRCUIT MALFUNCTION

Circuit Description

The AIR BAG warning lamp is controlled by the inflatable restraint sensing and diagnostic module (SDM) via
Class 2 serial data. When the ignition switch is first turned to the RUN position, the SDM performs tests to

Reprogram the vehicle theft deterrent (VTD) system. Refer to
Programming Theft Deterrent System Components in Theft
Deterrent.Did you complete the reprogramming procedure?

Go to

Step 9

1. Verify that all components, connectors, and CPAs are properly

mounted.

2. Use the scan tool in order to clear the DTCs.

3. 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

IMPORTANT: The following steps must be completed before using the Symptom Tables.

1. Perform the Diagnostic System Check - SIR before using the Symptom

Tables in order to verify that all of the following are true:

There are no DTCs set.

The control module(s) can communicate via the serial data link.

2. Review the system operation in order to familiarize yourself with the

system functions. Refer to SIR System Description and Operation .

2004 Hummer H2

2004 RESTRAINTS SIR - Hummer H2

diagnose critical malfunctions within itself. The SDM then commands the AIR BAG warning lamp OFF after it
has flashed seven times.

Diagnostic Aids

If Ignition 1 voltage is outside of the normal operating voltage range (9-16 volts), the AIR BAG warning
lamp will come ON solid with no DTCs set.

The loss of serial data communication between the inflatable restraint sensing and diagnostic module
(SDM) and the instrument panel cluster (IPC), will cause the AIR BAG warning lamp to come ON solid.
Refer to DTC U1001-U1254 in Data Link Communications.

Test Description

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

3: This step checks to see if the AIR BAG warning lamp flashes seven times when the ignition switch is
first turned to the RUN position.

4: This step checks to see if DTC U1088 is present in the instrument panel cluster (IPC).

5: This step checks to see if the AIR BAG warning lamp can be commanded ON.

6: This step checks to see if ignition 1 voltage to the SDM is more than 9 V.

7: This step determines if ignition 1 voltage to the SDM is more than 16 V or if there is a malfunctioning
SDM.

8: This step inspects the SDM wiring harness connector for corrosion or damage.

10: Tests for an open or high resistance in the ignition 1 voltage circuit between the SDM and the SIR
Fuse.

12: Tests for an open or high resistance in the ignition 1 voltage circuit to the SIR Fuse.

14: Tests for an open or high resistance in the SDM ground circuit or if there is a malfunctioning SDM.

Air Bag Indicator Circuit Malfunction

Step

Action

Value

(s)

Yes

Schematic Reference:SIR Schematics
Connector End View Reference:SIR Connector End Views

Did you perform the SIR Diagnostic System
Check?

Go to Step 2

Go to Diagnostic

System Check - SIR

Did you perform the Instrument Cluster
Diagnostic System Check?

Go to Step 3

Go to Diagnostic

System Check -

Instrument Cluster

in Instrument Panel,

Gauges and Console

1. Turn OFF the ignition.

2. Observe the AIR BAG warning lamp

while turning the ignition switch to the

2004 Hummer H2

2004 RESTRAINTS SIR - Hummer H2

RUN position.

Does the AIR BAG warning lamp flash seven
times?

Go to Step 4

Go to Step 17

1. Install a scan tool.

2. Establish communication with the

instrument cluster.

3. Use the scan tool to request the

instrument cluster DTC display.

Does the scan tool indicate that DTC U1088
is current?

Go to DTC U1001-

U1254 in Data Link

Communications

Go to Step 5

Use the scan tool to command the AIR BAG
warning lamp ON.
Does the AIR BAG warning lamp command
ON?

Go to Step 6

Go to Step 17

1. Establish communication with the

inflatable restraint sensing and
diagnostic module (SDM).

2. Use the scan tool to request the SIR

DTC display.

Does the ignition voltage displayed measure
more than the specified value?

9 V

Go to Step 7

Go to Step 8

Does the ignition voltage displayed measure
more than the specified value?

16 V

Go to Diagnostic

System Check -

Engine Electrical in

Engine Electrical

Go to Step 16

1. Turn OFF the ignition.

2. Disconnect the inflatable restraint

sensing and diagnostic module (SDM)
wiring harness connector. Refer to
Inflatable Restraint Sensing and
Diagnostic Module Replacement .

3. Inspect the SDM wiring harness

connector for signs of corrosion or
damage.

Does the connector exhibit any signs of
corrosion or damage?

Go to Step 9

Go to Step 10

Repair or replace the inflatable restraint
sensing and diagnostic module (SDM) wiring
harness connector. Refer to Connector
Repairs in Wiring Systems.

2004 Hummer H2

2004 RESTRAINTS SIR - Hummer H2

Did you complete the replacement?

Go to Step 18

1. Disable the SIR system.

2. UsingJ 39200 DMM measure the

resistance between the inflatable
restraint sensing and diagnostic module
(SDM) wiring harness connector
ignition 1 circuit and the output side of
the SIR Fuse. Refer to Circuit Testing
in Wiring Systems.

Does the resistance measure within the
specified value?

0-2

ohm

Go to Step 12

Go to Step 11

Locate and repair an open or high resistance
in the ignition 1 circuit between the SIR Fuse
and the SDM wiring harness connector. Refer
to Wiring Repairs in Wiring Systems.
Did you complete the repair?

Go to Step 18

1. Turn ON the ignition, with the engine

OFF.

2. UsingJ 39200 DMM measure the

voltage between the power feed to the
SIR Fuse and a known good ground.
Refer to Circuit Testing in Wiring
Systems.

Does the voltage measure near the specified
value?

12 V

Go to Step 14

Go to Step 13

Locate and repair an open or high resistance
in the power feed circuit to the SIR Fuse.
Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?

Go to Step 18

Using J 39200 DMM measure the resistance
of the inflatable restraint sensing and
diagnostic module (SDM) ground circuit
between the SDM wiring harness connector
and a known good ground. Refer to Circuit
Testing in Wiring Systems.
Does the resistance measure less than the
specified value?

2 ohm

Go to Step 16

Go to Step 15

Locate and repair an open or high resistance
in the inflatable restraint sensing and
diagnostic module (SDM) ground circuit.
Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?

Go to Step 18

Replace the inflatable restraint sensing and

2004 Hummer H2

2004 RESTRAINTS SIR - Hummer H2

Content .. 2062 2063 2064 2065 ..