Hummer H3. Manual — part 588

SIR Schematics

Connector End View Reference

SIR Connector End Views

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Circuit/System Testing

1. If DTC B3856 or B3857 is current, replace the ROS.

2. Test the signal and voltage circuits between the SDM and ROS for a short to voltage, short

to ground or open/low resistance. Verify that a short to voltage, short to ground or open/low
resistance does not exist.

If any of the above conditions are found make the appropriate repair.

3. Reconnect all SIR components. Ignition ON, use the scan tool to clear the DTCs then

recheck for DTCs. Verify DTC B3855 does not set.

If DTC B3855 was current, replace the ROS. After replacement, refer to Repair
Procedures.

Repair Procedures

Inflatable Restraint Vehicle Rollover Sensor Replacement

SIR/SRS Wiring Repairs

Control Module References for SDM replacement, setup and programming

Repair Verification

Ignition ON, use the scan tool to clear the DTC, then recheck for DTC.

If DTC B3855 was current replace the SDM.

DTC U1241

Diagnostic Instructions

2007 Hummer H3

2007 RESTRAINTS Supplemental Inflatable Restraints - H3

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC U1241 Lost Communication With Scan Tool

Circuit Description

The passenger presence system (PPS) monitors itself for faults and will set/flash DTCs if a fault is
detected. The PPS communicates with the inflatable restraint sensing and diagnostic module
(SDM) via non class 2 communications. When the SDM receives input from the PPS that a PPS
fault has occurred, the SDM will request the instrument panel cluster (IPC) to turn ON the AIR
BAG indicator located on the IPC. To determine what DTCs have been set by the PPS, the Tech
2 is used to command the SDM to request the PPS to flash the DTCs using the PASSENGER
AIR BAG ON/OFF indicators located on the instrument panel. The Tech 2 sends a string of
commands to the SDM that allows the SDM to communicate with the PPS module and initiate
the flashing of the DTCs. When the Tech 2 has completed sending the commands, the PPS will
begin flashing any current or history DTCs that the system has stored. When the SDM no longer
receives commands from the Tech 2, the SDM mistakes this as a communication fault and sets
DTC U1241. DTC U1241 will set when the Tech 2 is used to flash DTCs from the PPS or after
the PPS has been rezeroed. DTC U1241 does not indicate a system malfunction and will not
cause any warning indicators to illuminate. When DTC U1241 sets, cycle the ignition and use the
scan tool to clear the code, no further diagnosis is necessary. For more detailed information
concerning the PPS, refer to SIR System Description and Operation. For more detailed
information concerning PPS flash code and rezeroing procedures, refer to Passenger Presence
System Flash Code Procedures and Passenger Presence System Programming and Setup .

Conditions for Running the DTC

Ignition 1 voltage is within the normal operating voltage range.

Conditions for Setting the DTC

DTC U1241 will set when the Tech 2 is used to flash DTCs from the PPS or after the PPS has
been rezeroed.

Conditions for Clearing the DTC

A scan tool CLEAR DTC command is issued.

2007 Hummer H3

2007 RESTRAINTS Supplemental Inflatable Restraints - H3

Diagnostic Aids

DTC U1241 does not indicate a system malfunction and will not cause any warning indicators to
illuminate. When DTC U1241 sets, cycle the ignition and use the scan tool to clear the code, no
further diagnosis is necessary.

Reference Information

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

SYMPTOMS - SIR

Visual/Physical Inspection

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

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

IMPORTANT: The following steps must be completed before using the

Symptom Tables.

1. Perform the Diagnostic System Check - Vehicle , 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.

2007 Hummer H3

2007 RESTRAINTS Supplemental Inflatable Restraints - H3

Testing for Intermittent Conditions and Poor Connections .

Symptom List

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

Refer to Passenger Presence System Indicator Circuit Malfunction in order to diagnose the
symptom.

AIR BAG INDICATOR CIRCUIT MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit Description

When the ignition is turned ON, the instrument panel cluster (IPC) flashes the AIR BAG
indicator seven times. The inflatable restraint sensing and diagnostic module (SDM) performs
tests to diagnose critical malfunctions within the SIR system. If no SIR system malfunctions
exists, the SDM will request the IPC to turn the AIR BAG indicator OFF after it has flashed 7
times. The AIR BAG indicator is controlled by the SDM via class 2 serial data.

Diagnostic Aids

If ignition 1 voltage for the SDM is outside of the normal operating voltage range (9-16
volts), the AIR BAG indicator will come ON solid with no DTC set.

The loss of serial data communication between the SDM and the IPC will cause the AIR
BAG indicator to come ON solid. Refer to DTC U1001-U1254 .

Reference Information

Schematic Reference

SIR Schematics

Connector End View Reference

SIR Connector End Views

Electrical Information Reference

2007 Hummer H3

2007 RESTRAINTS Supplemental Inflatable Restraints - H3