Circuit Description
The inflatable restraint Sensing and Diagnostic and Seat Belt Pretensioner
Module (SDM) performs Turn-On tests to diagnose critical malfunctions within
itself when the ignition switch is turned ON. The SDM monitors the six firing
loops to detect leakage currents to ground and system voltage in the frontal
and side air bag inflator module and seat belt pretensioner circuits. Then,
the SDM proceeds with the Resistance Measurement test to measure the deployment
loop resistances to ensure they are within their respective normal resistance
ranges. Upon passing these tests, and if the energy reserve is charged up,
the firing transistors are tested. The SDM then goes into Continuous Monitoring
mode. The SDM service wait time is 1 minute. Refer to On-Vehicle Service for
enable/disable procedures.
Conditions for Setting the DTC
The driver frontal air bag deployment loop resistance is less than 1.7 ohms.
The driver frontal air bag deployment loop consists of the following components.
| • | Inflatable restraint steering wheel module. |
| • | Inflatable restraint steering wheel module coil. |
| • | Harness wiring of CKT BM30. |
| • | Harness wiring of CKT B30. |
| • | Connector terminal contacts, including shorting bars. |
The deployment loop resistance test checks for this malfunction.
Action Taken When the DTC Sets
| • | The SDM sets a Diagnostic Trouble Code. |
| • | The SDM turns ON the AIR BAG warning lamp. |
Conditions for Clearing the DTC
The resistance of the driver deployment loop is greater than 1.7 ohms.
Current and History DTC codes must be cleared using a scan tool Clear
DTC Information command. If the circuit fault has been successfully repaired
and the conditions which caused the Current DTC 32 to set are no longer
existing, History DTC 32 will set. History DTC 32 may be cleared
using the scan tool.
Diagnostic Aids
The following can cause an intermittent condition:
| • | A short circuit between CKTs BM30 and B30. |
| • | A malfunctioning shorting bar in the inflatable restraint steering
wheel module. |
| • | A malfunctioning shorting bar in the inflatable restraint steering
wheel module coil . |
| • | A malfunctioning shorting bar on the inflatable restraint SDM
harness connector above SDM harness connector terminals 1 and 2. |
Inspect CKTs BM30 and B30 carefully for cutting and/or chafing. The
diagnostic table directs the technician to note the value of DRIVER AIR BAG
RES. Comparing the value of DRIVER AIR BAG RES. over multiple ignition cycles
can be helpful in determining if an intermittent condition exists.
When measurements are requested in this table,
use J 39200
Digital Multimeter
with the correct terminal adapter from J 35616
Connector Test Adapter Kit. When a check for proper connection
is requested, refer to General Electrical Diagnosis Procedures
in Wiring Systems. When a wire, connector or terminal repair
is requested, use J-38125
Terminal
Repair Kit and refer to Wiring Repair
.
Test Description
The numbers below refer to step numbers on the diagnostic table.
-
This
test determines whether the malfunction is in the inflatable restraint steering
wheel module. This is done by substituting the known good resistance of
the inflatable restraint steering wheel module. Then, observing if the malfunction
is still present.
-
This test determines whether the malfunction is in the
inflatable restraint steering wheel module coil.
-
This test determines
whether the malfunction is between CKT BM30 and CKT B30.
DTC 32 Driver Air Bag Deploy. Loop Resistance Low
Step
| Action
| Value(s)
| Yes
| No
|
1
| Was the SIR Diagnostic System Check performed?
| --
|
Go to Step 2
| Go to
SIR Diagnostic System Check
|
2
|
- Turn the ignition switch to the OFF position.
- Connect a scan tool to the DLC.
- Turn the ignition switch to the ON position.
- Request the SIR data list display.
- Read and record on the repair order the driver frontal air bag
deployment loop resistance DRIVER AIR BAG RES.
Has DRIVER AIR BAG RES. been read and recorded on the repair order?
| --
|
Go to Step 3
| --
|
3
|
- Turn the ignition switch to the OFF position.
- Wait one minute until the SDM energy reserve capacitors have discharge.
- Disconnect the negative battery cable. Refer to
Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing
any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to
the vehicle or its components.
.
- Disconnect the inflatable restraint steering wheel module. Refer
to Steering Wheel Inflator Module Replacement
in Steering Wheel and Column--Tilt.
- Use the J 38715-30 adapter to connect the J 38715-A
SIR Driver/Passenger Load Tool STEERING
COLUMN connector to the inflatable restraint steering wheel module integral
harness connector.
- Reconnect the negative battery cable.
- Turn the ignition switch to the ON position.
- Use the scan tool to request the SIR data list display.
- Read the driver frontal air bag deployment loop resistance DRIVER
AIR BAG RES.
Is the DRIVER AIR BAG RES. less than the specified value?
| 1.7 ohms
|
Go to Step 5
|
Go to Step 4
|
4
|
- Turn the ignition switch to the OFF position.
- Inspect the inflatable restraint steering wheel module integral
harness connector for damage.
- Ensure the nearby wiring is routed correctly.
- Replace the inflatable restraint steering wheel module. Refer
to Steering Wheel Inflator Module Replacement
in Steering Wheel and Column--Tilt.
Is the replacement complete?
| --
|
Go to Step
14
| --
|
5
|
- Turn the ignition switch to the OFF position.
- Wait one minute until the SDM energy reserve capacitors have discharged.
- Disconnect the negative battery cable. Refer to
Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing
any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to
the vehicle or its components.
.
- Remove the inflatable restraint steering wheel module coil from
the top of the steering column. Refer to Steering Wheel Inflator Module Coil Replacement
in Steering Wheel
and Column--Tilt.
- Use the J 39715 -40 adapter to connect the J 38715-A
SIR Driver/Passenger
Load Tool BASE OF COLUMN connector to the inflatable restraint steering wheel
module coil connector at the top of the steering column.
- Turn the ignition switch to the ON position.
- Use the scan tool to request the SIR data list display.
- Read the driver frontal air bag deployment loop resistance DRIVER
AIR BAG RES.
Is the DRIVER AIR BAG RES. less than the specified value?
| 1.7 ohms
|
Go to Step 7
|
Go to Step 6
|
6
|
- Turn the ignition switch to the OFF position.
- Disconnect the J 38715-A
SIR Driver/Passenger Load Tool.
- Inspect the inflatable restraint steering wheel module coil for
damage.
- Inspect the inflatable restraint steering wheel module coil connecting
wires for damage.
- Replace the inflatable restraint steering wheel module coil. Refer
to Steering Wheel Inflator Module Coil Replacement
in Steering Wheel and Column--Tilt.
Is the replacement complete?
| --
|
Go to Step
14
| --
|
7
|
- Turn the ignition switch to the OFF position.
- Wait one minute until the SDM energy reserve capacitors have discharged.
- Disconnect the negative battery cable. Refer to
Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing
any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to
the vehicle or its components.
.
- Disconnect the inflatable restraint Sensing and Diagnostic Module
(SDM). Refer to
Inflatable Restraint Sensing and Diagnostic and Seat Belt Pretensioner Module Replacement
.
- Check for proper connection at terminals 1 and 2 on the SDM harness
connector.
Are the terminals damaged and/or corroded?
| --
|
Go to Step 7
|
Go to Step
8
|
8
| Replace the IP harness.
Is the replacement complete?
| --
|
Go to Step
9
| --
|
9
| Check for proper connection at terminals 1 and 2 on the SDM.
Are the terminals damaged and/or corroded?
| --
|
Go to Step 11
|
Go to Step
14
|
10
| Check for proper connection at terminals 1 and 2 on the
SDM.
Are the terminals damaged and/or corroded?
| --
|
Go to Step 11
|
Go to Step
12
|
11
| Replace the inflatable restraint Sensing and Diagnostic
Module (SDM). Refer to
Inflatable Restraint Sensing and Diagnostic and Seat Belt Pretensioner Module Replacement
.
Is the replacement complete?
| --
|
Go to Step
14
-
| --
|
12
|
- Disconnect the J 38715-A
SIR Driver/Passenger Load Tool.
- Insert the J 42113
Shorting Bar Tool into the SDM harness connector terminal above terminals
1 and 2. This opens the short circuit bridge between terminals 1 and 2.
- Zero the J 39200
Digital
Multimeter.
- Use the J 39200
Digital
Multimeter to measure the resistance on the SDM harness connector from terminal 1
to terminal 2.
Is the resistance reading within the specified value?
| 0-0.5 ohms
|
Go to Step 13
| Go to
Integrity Check
|
13
| Repair the short circuit between
CKT BM30 and CKT B30.
Is the repair complete?
| --
|
Go to Step
14
| --
|
14
| Reconnect all the SIR system components. Ensure all the components are
properly mounted.
Are all the SIR system components reconnected and are all the SIR system
components properly mounted?
| --
|
Go to Step
15
| --
|
15
| Clear the SIR diagnostic trouble codes.
Are the SIR diagnostic trouble codes cleared?
| --
| Go to
SIR Diagnostic System Check
| --
|
