Circuit Description
The inflatable restraint Sensing and Diagnostic and Seat Belt Pretensioner
Module (SDM) performs 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. The deployment
loop resistances are measured to ensure they are within their respective normal
resistance ranges. The SDM does the following during one portion of the Resistance
Measurement test:
| • | Measure the voltage difference between the DRIVER FRONTAL HIGH
and the DRIVER FRONTAL LOW. |
| • | Uses the measured voltage to calculate the resistance of the driver
deployment loop. |
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 deployment loop resistance is more than 6.0 ohms.
The driver deployment loop consists of the following components:
| • | The inflatable restraint steering wheel module. |
| • | The inflatable restraint steering wheel module coil. |
| • | The harness wiring of CKT BM30. |
| • | The harness wiring of CKT B30. |
| • | The connector terminal contact. |
The Resistance Measurement test checks for this malfunction. This test
only occurs once each ignition cycle when the IGNITION is within the normal
operating voltage range.
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 less than 6.0 ohms.
You must issue a scan tool Clear Codes command to clear a Current or
History code.
Diagnostic Aids
A poor connection can cause an intermittent condition. Check the following
for a poor connection:
| • | Check the inflatable restraint steering wheel module coil integral
2-way connector terminals 1 and 2. |
| • | Check the inflatable restraint steering wheel module coil connector
terminals 7 and 8. |
| • | Check the SDM terminals 1 and 2. |
| • | Check the wire to terminal connections in CKT BM30. |
| • | Check the wire to terminal connections in CKT B30. |
The diagnostic table directs the technician to note the entry value
of the Driver Air Bag Resistance. Comparing the value of the Driver Air Bag
Resistance 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 in CKT BM30.
-
This test determines whether the malfunction
is in CKT B30.
DTC 31 Driver Air Bag Deploy. Loop Resistance High
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 RUN 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 RUN 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. more than the specified value?
| 6.0 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 RUN 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. more than the specified value?
| 6.0 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 body 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 16
|
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
16
-
| --
|
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 the inflatable restraint steering wheel module coil connector terminal 7.
Is the resistance reading within the specified value?
| 0-0.5 ohms
|
Go to Step 14
|
Go to Step 13
|
13
| Repair the open circuit or high resistance condition in
CKT BM30.
Is the repair complete?
| --
|
Go to Step
16
| --
|
14
|
- Zero the J 39200
Digital
Multimeter.
- Use the J 39200
Digital
Multimeter to measure the resistance on the SDM harness connector from terminal 2
to the inflatable restraint steering wheel module coil connector terminal 8.
Is the resistance reading within the specified values?
| 0-0.5 ohms
| Go to
Integrity Check
|
Go to Step 15
|
15
| Repair the open circuit condition or high resistance in
CKT B30.
Is the repair complete?
| --
|
Go to Step
16
| --
|
16
| 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
17
| --
|
1
| Clear the SIR diagnostic trouble codes.
Are the SIR diagnostic trouble codes cleared?
| --
| Go to
SIR Diagnostic System Check
| --
|
