Supplemental Inflatable Restraint System Cadillac DeVille Concours

IDENTIFICATION

All models equipped with a Supplemental Inflatable Restraint (SIR) system have a number "2" (driver and passenger-side air bag modules) in the seventh position of the Vehicle Identification Number (VIN). The words Inflatable Restraint are marked on the steering wheel hub. Steering wheel hub is slightly larger in order to accommodate the driver-side air bag module.

SUPPLEMENTAL INFLATABLE RESTRAINT (SIR) SYSTEM

The Supplemental Inflatable Restraint (SIR) system is designed to protect the driver and passenger in a frontal collision. The air bag modules will deploy only upon frontal or near frontal impact of no more than 30 degrees off the center line of vehicle. System is not designed to deploy in rear impacts, side impacts, or rollovers. A frontal impact of sufficient severity (comparable to a collision into a solid wall at approximately 14 MPH or more) will cause sensors in vehicle to detect this sudden deceleration. These sensors, in turn, trigger the air bag modules.

SENSING AND DIAGNOSTIC MODULE (SDM)

The SDM monitors vehicle velocity changes to detect frontal crashes which are severe enough to warrant air bag module deployment. When a frontal crash of sufficient force is detected, SDM will cause enough current to flow through air bag modules to deploy air bag modules. The SDM also maintains a 36 Volt Loop Reserve (36 VLR) energy supply to provide deployment energy in cases where ignition voltage is lost in a frontal crash.

Additionally, the SDM provides diagnostic monitoring of the SIR system electrical components. When a malfunction is detected, the SDM sets a diagnostic trouble code (DTC) which is retrieved using a scan tool. The SDM warns the driver of system malfunctions by controlling the AIR BAG warning light.

AIR BAG WARNING LIGHT

When ignition switch is in RUN or START positions, battery voltage is applied to AIR BAG warning light. SDM illuminates this light by providing a ground to a lamp driver. When ignition is first turned on, AIR BAG warning light verifies light and SDM operation by flashing 7 times. Light is also used to warn driver of SIR electrical system faults which could potentially affect SIR system operation. AIR BAG warning light is the key to driver notification of SIR system faults.

FRONT END DISCRIMINATING SENSOR

The front end discriminating sensor is an auxiliary sensor which assists the SDM in determining when deployment should occur by providing the SDM with an input signal. Although the front end discriminating sensor is a mechanical sensor, it is not part of the deployment loop.

SIR COIL ASSEMBLY

SIR coil assembly consists of 2 or more current-carrying coils. It is installed in steering column and allows rotation of steering wheel while maintaining continuous (directly wired) contact of deployment loop through driver-side air bag module.

There is a shorting bar on the Yellow 2-way connector near base of steering column which connects SIR coil assembly to SIR wiring harness. The shorting bar shorts the circuits to main coil and driver-side air bag module when Yellow 2-way connector is disconnected. This shorts the circuit to the driver-side air bag module, preventing unwanted deployment of the air bag module when servicing the steering column or other SIR components.

AIR BAG MODULES

When the vehicle is in an accident of sufficient force to close the discriminating sensor, nitrogen gas inflates the cloth bag packed inside the steering wheel hub and in passenger-side instrument panel. The bag(s) inflate in less than 1/20 of a second. As air bag is contacted by driver or passenger, the gas is vented through openings in the bag, which deflates almost as soon as it is completely deployed.

KNEE BOLSTERS

Knee bolsters are used to absorb energy and control forward movement of front passengers. This is accomplished by limiting leg movement during a frontal crash.

SERVICE PRECAUTIONS

The following precautions should be observed when working with SIR system

1. The SDM maintains sufficient voltage to cause air bag deployment for up to 10 minutes after ignition is turned OFF, battery is disconnected, or fuse powering SDM is removed. In order to begin servicing immediately, inflator modules must be removed from the deployment loop. See «DISABLING SYSTEM»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__disabling-system) .
2. After repairs, ensure AIR BAG warning light is working properly and no system faults are indicated. See «SYSTEM OPERATION CHECK»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__system-operation-check) .
3. Always wear safety glasses when servicing or handling an air bag module.
4. Air bag module must be stored in its original special container until used for service. It must be stored in a clean, dry place, away from sources of extreme heat, sparks, or high electrical energy.
5. Air bag modules or SDMs should not be subjected to temperatures above 150°F (65°C).
6. Air bag modules or SDMs should not be used if they have been dropped from a height of 3 ft (0.9 m) or greater.
7. When placing a live air bag module on a bench or other surface, always make certain that the trim cover (finished side) is up and away from surface. This will reduce motion of module if accidentally deployed.
8. After deployment, air bag surface may contain deposits of sodium hydroxide, which can irritate skin. Always wear safety glasses, rubber gloves and long-sleeved shirt during clean-up, and wash hands using mild soap and water. Follow correct disposal procedures. See «DISPOSAL PROCEDURES»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__disposal-procedures) .
9. At no time should any electrical source be allowed near inflator on back of air bag module.
10. DO NOT apply power to SIR system unless all components are connected or a diagnostic chart requests it, as this will set a diagnostic trouble code.
11. When carrying a live air bag module, trim cover should be pointed away from your body to minimize injury in case of accidental deployment.
12. DO NOT attempt to service SDM, front end discriminating sensor, SIR coil assembly, or air bag modules. If defective, these parts must be replaced.
13. DO NOT probe a wire through insulator; this will damage it and eventually cause failure due to corrosion.
14. When performing electrical tests, prevent accidental shorting of terminals. Such mistakes can damage fuses or components and may cause a second fault code to set, making diagnosis of original problem more difficult.
15. When using diagnostic charts to diagnose SIR system, under no circumstances should a volt/ohmmeter, test light or any type of electrical equipment not specified by manufacturer be used. See «SPECIAL TOOLS»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__special-tools) .
16. If SIR system is not fully functional for any reason, vehicle should not be driven until system is repaired. DO NOT remove bulbs, modules, sensors or other components or in any way disable system from operating normally. If SIR system is not functional, park vehicle until repairs can be made.

SPECIAL TOOLS

To avoid deployment when working on SIR system, DO NOT use electrical test equipment such as test lights, battery or A/C-powered volt/ohmmeter, or any type of electrical equipment other than those specified by manufacturer. See SIR RECOMMENDED TOOLS table.

SIR RECOMMENDED TOOLS

DISABLING & ACTIVATING AIR BAG SYSTEM

DISABLING SYSTEM

Note. When AIR BAG fuse is removed and ignition switch is in RUN, the AIR BAG warning light will be on. This does not indicate a system malfunction.

1. Turn steering wheel to place vehicle wheels in straight-ahead position. Turn ignition switch to LOCK position.
2. Remove SIR fuse from trunk fuse block, located behind carpet in left front corner of trunk. Remove left sound insulator panel. Remove Connector Position Assurance (CPA) clip and disconnect driver-side Yellow 2-way connector and CPA at base of steering column. Disconnect passenger-side Yellow 2-way connector and CPA through trap door in glove box.

ACTIVATING SYSTEM

Turn ignition to LOCK position. Connect passenger-side Yellow 2-way connector and CPA through trap door in glove box. Connect driver-side Yellow 2-way connector and CPA at base of steering column. Install left sound insulator panel and SIR fuse. Turn ignition switch to RUN position and perform SYSTEM OPERATION CHECK .

POST-COLLISION INSPECTION

When a vehicle has been involved in a collision, certain components of the passive restraint system must be inspected or replaced. See PASSIVE RESTRAINT SYSTEM INSPECTION article in the GENERAL INFORMATION section for post-collision inspection information.

Scheme 1

1. If coil assembly has been removed from steering column and is being reinstalled, go to next step. New coil assemblies are provided pre-centered and include a Blue plastic tab that is snapped off once coil is installed. (Scheme 1)
2. Ensure front wheels face straight ahead when installing or removing a coil assembly. If coil is removed without wheels in straight-ahead position and steering wheel has not been moved, same coil can be reinstalled if coil hub has not been rotated.
3. Hold coil assembly with clear bottom upward to see coil ribbon. While holding coil assembly housing, depress spring lock and rotate hub in direction of arrow until it stops. Coil ribbon should now be wound up snug against center hub. Rotate coil hub in opposite direction approximately 2 1/2 turns. Release spring lock between locking tabs next to arrow. (Scheme 1)

DISPOSAL PROCEDURES

ON-VEHICLE DEPLOYMENT

1. Turn ignition switch to LOCK position. Disconnect driver-side and passenger-side air bag module Yellow 2-pin connectors. Cut air bag module harness connector from vehicle leaving at least 6 in (16 cm) of wire at the connector.
2. Strip 1/2 in (13 mm) of insulation from each wire lead to the connector. Cut 2 deployment wires at least 20 feet (610 cm) long from 18 gauge (0.8 mm 2 ) multi-strand wire. Strip 1/2 in (13 mm) of insulation from both ends of wire. Twist ends of wire together to short.
3. Twist together one connector wire lead to one deployment wire. (Scheme 2) Bend twisted connection flat and wrap tightly with electrical tape to insulate. Repeat this step for the other connector wire lead.
4. Remove all loose objects from front seat, and ensure no one is in vehicle. Connect deployment harness to air bag module Yellow 2-way connector. Stretch wires away from car as far as possible.
5. Repeat steps 1-4 for passenger-side air bag module.
6. Connect wires to a 12-volt battery. Air bags should deploy. DO NOT touch air bag module area for at least 10 minutes due to heat generated during deployment. Wear gloves and safety glasses before handling deployed air bag module. Wash hands with mild soap and water afterward. Deployed air bag modules can be disposed of like any other part.Repeat deployment procedure for passenger-side air bag.
7. Carefully remove air bag modules if they do not deploy. See «AIR BAG MODULE»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system) under REMOVAL & INSTALLATION. Temporarily store module with trim facing up. Contact manufacturer for further instructions.

Scheme 2

OFF-VEHICLE DEPLOYMENT

1. Turn ignition switch to LOCK position. Short the two deployment harness (J-38826) leads together by fully seating one banana plug into the other. Connect pigtail adapter to SIR deployment harness.
2. Remove driver-side air bag module. See «AIR BAG MODULES»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__air-bag-modules) under REMOVAL & INSTALLATION. Place air bag module on a work bench with trim cover facing up.
3. Place air bag module on ground (preferably outdoors) at least 6 feet (1.85 m) away from any people or objects. Stretch SIR deployment harness and pigtail adapter from air bag module to its full length. Place a 12-volt battery near shorted end of SIR deployment harness.
4. Connect air bag module to pigtail adapter on SIR deployment harness. (Scheme 3) Ensure area around air bag module is clear of people and objects. Verify that air bag module is resting with trim cover facing up.
5. Separate the two banana plugs on SIR deployment harness. Connect SIR deployment harness wires to battery. (Scheme 3) Air bag module will deploy immediately. If air bag module does not deploy, go to next step. Disconnect SIR deployment harness from battery. Short the two SIR deployment harness leads. DO NOT touch air bag module area for at least 10 minutes due to heat generated during deployment. Wear gloves and safety glasses before handling deployed air bag module. Wash hands with mild soap and water afterward. Dispose of deployed air bag modules as you would any other part. Repeat deployment procedure for passenger-side air bag module.
6. Ensure that SIR deployment harness is disconnected from battery and that the two banana plugs have been shorted together. Disconnect pigtail adapter from air bag module. Temporarily store air bag module with trim cover facing up. Contact manufacturer for further instructions.

Scheme 3

REMOVAL & INSTALLATION

Removal

1. Before proceeding, read air bag service precautions section. See «SERVICE PRECAUTIONS»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__service-precautions). Disable air bag system. See «DISABLING SYSTEM»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__disabling-system).
2. Remove driver seat. Remove left front sill plate. Fold back carpet and insulation to access SDM. Remove connector position assurance (CPA) clip and disconnect electrical connector. Remove SDM fasteners. (Scheme 4) Remove SDM.

Scheme 4

Installation

1. Mount SDM on vehicle, ensuring arrow is pointing toward front of vehicle. Install SDM fasteners. (Scheme 4) Tighten to specification. See «TORQUE SPECIFICATIONS»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__torque-specifications). Reconnect electrical connector and CPA.
2. Position carpet and insulation over SDM. Install driver seat and left front sill plate. Reactivate air bag system. See «ACTIVATING SYSTEM»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__activating-system). Ensure system is functioning properly. See «SYSTEM OPERATION CHECK»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__system-operation-check).

1. Before proceeding, read air bag service precautions section. See «SERVICE PRECAUTIONS»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__service-precautions). Disable air bag system. See «DISABLING SYSTEM»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__disabling-system).
2. Remove underhood fuse block cover. Remove CPA clip and disconnect electrical connector. Remove plastic radiator support cover and air cleaner housing cover. Remove sensor pigtail clips and sensor fasteners. Remove sensor. (Scheme 5)

Scheme 5

1. Align sensor to vehicle, ensuring arrow on sensor body is pointing toward front of vehicle. Install and tighten sensor fasteners. See «TORQUE SPECIFICATIONS»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__torque-specifications) . Install plastic radiator support cover. Install sensor pigtail clips. Install air cleaner housing cover. Reconnect electrical connector and reinstall CPA clip. Install underhood fuse block cover.
2. Reactivate air bag system. See «ACTIVATING SYSTEM»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__activating-system) . Ensure proper system function. See «SYSTEM OPERATION CHECK»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__system-operation-check) .

1. Before proceeding, read air bag service precautions section. See «SERVICE PRECAUTIONS»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__service-precautions) . Disable air bag system. See «DISABLING SYSTEM»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__disabling-system) .
2. Remove air bag module. See «AIR BAG MODULE»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system) . Remove steering wheel nut. Using steering wheel puller (J-1859-03), remove steering wheel.
3. To install steering wheel, feed coil assembly lead through slot in steering wheel. Install steering wheel and tighten nut to specification. See «TORQUE SPECIFICATIONS»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__torque-specifications) . Install driver-side air bag module. See Installation (Driver-Side) under «AIR BAG MODULE»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system) in this section.
4. Reactivate air bag system. See «ACTIVATING SYSTEM»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__activating-system) . Ensure proper system function. See «SYSTEM OPERATION CHECK»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__system-operation-check) .

Note. Front wheels of vehicle must be turned to straight-ahead position before beginning service. Failure to do so can result in coil assembly being removed without being centered. Reinstalling coil assembly under such circumstances causes ribbon in coil assembly to break when steering wheel is turned fully in one direction. Ensure key is always in LOCK position to prevent wheel from turning and uncentering coil assembly. To re-center coil assembly, see CENTERING COIL ASSEMBLY under ADJUSTMENTS.

1. Before proceeding, read air bag service precautions section. See «SERVICE PRECAUTIONS»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__service-precautions). Disable air bag system. See «DISABLING SYSTEM»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__disabling-system).
2. Remove air bag module. See «AIR BAG MODULE»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system). Remove steering wheel. See «STEERING WHEEL»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system). Remove coil assembly retaining clip. Remove coil assembly off shaft end letting coil hang freely. (Scheme 6)
3. Remove wave washer. Using Lock Plate Compressor (J-23563-SIR), depress shaft lock and remove shaft lock retaining ring. Remove shaft lock. Remove turn signal canceling cam assembly. Remove upper bearing spring, inner race seat, and inner race.
4. Turn signal to right turn (up) position. Remove multifunction lever and hazard knob assembly. Remove turn signal switch arm. Remove turn signal switch assembly. Attach mechanics wire to coil assembly lower connector at base of steering column and carefully pull wire through gear shift lever bowl, column housing and lock housing cover. Remove mechanic's wire.

Scheme 6

1. Using a mechanic's wire, carefully feed coil assembly wire and lower connector through lock housing cover, column housing, and gear shift lever bowl. Allow coil assembly to hang freely. Remove mechanic's wire. Install wiring protector.
2. Install turn signal switch assembly and arm. Tighten screws to specification. See «TORQUE SPECIFICATIONS»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__torque-specifications) . Install hazard knob assembly and multifunction lever. Install inner race, upper bearing inner race seat, and spring. Install turn signal canceling cam and shaft lock. Install NEW shaft lock retaining ring. Using lock plate compressor (J-23653-SIR), align block tooth on shaft, and depress shaft lock plate. Install wave washer.
3. Ensure coil assembly hub and steering shaft are centered. See «CENTERING COIL ASSEMBLY»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system) under ADJUSTMENTS. Coil assembly will become uncentered if column is separated from steering gear and is allowed to rotate, or if centering spring is depressed, allowing hub to rotate while coil assembly is removed from column.
4. Install coil assembly, using horn tower on canceling cam to align hole on inner ring of coil and projections on steering column housing with projections on outer ring of coil.
5. Install steering wheel. See «STEERING WHEEL»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system) . Install driver-side air bag module. See «AIR BAG MODULE»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system) . Reactivate air bag system. See «ACTIVATING SYSTEM»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__activating-system) . Ensure proper system function. See «SYSTEM OPERATION CHECK»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__system-operation-check) .

Removal (Driver-Side)

1. Before proceeding, read air bag service precautions section. See «SERVICE PRECAUTIONS»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__service-precautions). Disable air bag system. See «DISABLING SYSTEM»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__disabling-system).
2. Loosen 4 screws from back of steering wheel until back of air bag module can be accessed. (Scheme 7) Disconnect horn contact by pushing slightly and twisting counterclockwise. Disconnect CPA and coil assembly connector from air bag module. Remove air bag module.

Scheme 7

Installation (Driver-Side)

1. Turn ignition off. Connect horn contact to steering column. Connect coil assembly connector and CPA to air bag module. Install air bag module to steering wheel, ensuring no wires are pinched. Tighten 4 air bag module screws through back of steering wheel. Tighten screws to specification. See «TORQUE SPECIFICATIONS»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__torque-specifications) .
2. Reactivate air bag system. See «ACTIVATING SYSTEM»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__activating-system) . Ensure proper system function. See «SYSTEM OPERATION CHECK»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__system-operation-check) .

Removal (Passenger-Side)

1. Before proceeding, read air bag service precautions section. See «SERVICE PRECAUTIONS»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__service-precautions). Disable air bag system. See «DISABLING SYSTEM»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__disabling-system).
2. Remove instrument panel upper trim pad. Remove bracket fastener behind trap door in rear of glove box. Remove 4 air bag module fasteners. Remove passenger-side air bag module and pigtail. (Scheme 8)

Scheme 8

Installation (Passenger-Side)

Turn ignition off. Install air bag module and pigtail. Install 4 air bag module fasteners to specification. See TORQUE SPECIFICATIONS . Install bracket fastener behind trap door in rear of glove box and tighten to specification. Install instrument panel upper trim pad. Reactivate air bag system. See ACTIVATING SYSTEM . Ensure proper system function. See SYSTEM OPERATION CHECK .

SYSTEM OPERATION CHECK

If system is functioning normally, air bag warning light will flash 7 times and then go out when ignition switch is turned to ON position.

Four possible warning light conditions can indicate a system failure

1. Light does not illuminate at all.
2. Light comes on while vehicle is driven.
3. Light flashes 7 times, and remains on.
4. Light does not flash but remains lit when ignition is turned on.

SIR system faults are usually due to a disconnected/loose electrical connector caused by previous service on vehicle. Always check Yellow SIR connector at base of steering column for loose or damaged wiring.

WIRE REPAIR

Because of sensitive nature of circuitry, manufacturer has developed special wiring repair procedures. Wire Repair Kit (J-38125-A) contains special sealed splices for use in repairing SIR wiring. Sealed splices are a heat shrink sleeve with sealing adhesive to produce a sealed splice and a cross-hatched core crimp to produce a positive contact for low energy circuits.

If any terminal or connector in SIR wire harness (except pigtails) is damaged, component can be repaired using one of connector repair assembly packs. Terminals in SIR system are manufactured from a special metal to provide necessary contact for low energy circuits. These terminals are only available in wiring kit, and no other terminal should be substituted.

If an SIR wire pigtail is damaged, entire component (including pigtail) should be replaced. Under no circumstances should wire, connector or terminal repair be attempted on passenger compartment discriminating sensor, forward discriminating sensor, air bag module, or SIR coil assembly.

If any wire except a pigtail is damaged, wire can be repaired by splicing in a new section of wire of same gauge. Sealed splices and crimping tool must be used for these splices. To open wiring harness, remove tape as necessary. To avoid wire insulation damage, manufacturer recommends use of a sewing seam ripper. Refer to instructions in kit for wire repair procedure.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

CONNECTOR IDENTIFICATION

Note. To identify SIR wiring connector terminals (Scheme 9)

Scheme 9

DIAGNOSIS & TESTING

Diagnostic Trouble Codes (DTCs)

The Sensing & Diagnostic Module (SDM) provides a record of DTCs stored according to type. The SDM performs diagnostic monitoring of the SIR system electrical components and sets a diagnostic trouble code (DTC) when a malfunction is detected. Current DTCs are stored in SDM and are erased when fault is corrected. Current DTCs can be read using a scan tool such as Tech 1.

Scan Tool Diagnostics

A scan tool will read and clear current codes and history codes. Ensure scan tool contains correct cartridge for SIR diagnostics. To use scan tool, connect it to DLC connector, plug in power source and turn ignition switch to RUN position. Follow scan tester manufacturer instructions for communication with SIR system. Scan tester reads serial data from SDM data link output to DLC connector.

Diagnostic Procedure

1. SIR SYSTEM DIAGNOSTIC CHECK should always be starting point of SIR diagnostics. See «SIR DIAGNOSTIC SYSTEM CHECK»(/cadillac/deville-concours/1994-1998/remont/airbag/#supplemental-inflatable-restraint-system__sir-diagnostic-system-check) under DIAGNOSTIC CHARTS. SIR DIAGNOSTIC SYSTEM CHECK checks for proper INFLATABLE RESTRAINT indicator light operation and SIR trouble codes using flash code and scan tester methods.
2. SIR DIAGNOSTIC SYSTEM CHECK will lead to correct diagnostic chart to diagnose SIR problems. Always perform SIR DIAGNOSTIC SYSTEM CHECK after repair or diagnostic procedures to ensure repair is correct and no other problems are present.

On-Board Diagnostics

1. To display DTCs, turn ignition on. Press the OFF and WARMER (digital cluster) and PASSENGER WARMER (analog cluster) buttons of the Climate Control Center simultaneously until all segments of display are on.
2. Each DTC will be displayed with its status, current or history. The order of system DTC display will be as follows: PCM, IPC, ACM, SDM, TCS, RSS, PZM, IRC, RFA, CCP, PHN. Pressing the LO button will display the next available system selection.

SIR DIAGNOSTIC SYSTEM CHECK

Description

When ignition switch is turned ON, IGNITION 1 voltage is applied from SIR fuse to SDM at IGNITION 1 input terminal No. B9 and from RLY IGN 1 fuse to SDM at REDUNDANT INDICATOR IGNITION 1 input terminal No. A4. SDM responds by flashing AIR BAG indicator 7 times then turning off while performing tests on SIR system.

When engine is being cranked, IGNITION 1 voltage is applied from CRANK fuse to SDM at CRANK input terminal No. B1. SDM responds by grounding SIR indicator output terminal No. A9 until IGNITION 1 voltage is removed from CRANK input. This results in AIR BAG warning light being ON steady during cranking. After cranking SDM will flash AIR BAG warning light six times and perform tests on SIR system.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. AIR BAG indicator should flash 7 times after ignition switch is turned to ON.
2. AIR BAG indicator should remain ON steady during cranking.
3. After cranking, AIR BAG warning light should flash six times then go OFF.
4. This test checks the Serial Data line and will determine whether history diagnostic trouble codes are stored and, if so, identify them.
5. When AIR BAG warning light flashes four times during bulb check this indicates malfunction in redundant light driver circuitry. These malfunctions are diagnosed by DTC SD1062.
6. Improper operation of AIR BAG indicator is indicated. This test differentiates an indicator stays ON condition from an indicator does not come ON condition.
7. This test checks the Serial Data line and will identify stored diagnostic trouble codes and whether they are current or history.

Diagnostic Aids

The order in which diagnostic trouble codes are diagnosed is very important. Failure to diagnose trouble codes in order specified may result in extended diagnostic time, incorrect diagnosis and parts replacement.

Scheme 10

CHART A - SDM INTEGRITY CHECK

When SDM recognizes IGNITION 1 voltage applied to terminal No. B9 is greater than 7 volts, AIR BAG indicator is flashed 7 times to verify operation. At this time SDM performs Turn ON tests followed by CURRENT SOURCE DIAGNOSTICS and CONTINUOUS MONITORING tests. When a malfunction is detected, SDM sets a current diagnostic trouble code and turns AIR BAG indicator ON. SDM will clear current diagnostic trouble codes and move them to a history file when malfunction is not longer detected and/or ignition switch is cycled, except for DTC SD1051, SD1052 and SD1071. DTC SD1051 can only be cleared using scan tool clear codes command. DTC SD1052 and SD1071 may not clear after clear codes command is issued.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. This test confirms a current malfunction. If not current malfunction is occurring (History DTC set) Diagnostic Aids for appropriate diagnostic trouble code should be referenced. SDM should not be replaced for a History DTC except when directed.
2. This test checks for a malfunction introduced into SIR system during diagnostic process. It is extremely unlikely that a malfunctioning SDM would cause a new malfunction to occur during diagnostic process.
3. When all circuitry outside SDM has been found to operate properly, as indicated by appropriate diagnostic chart, then and only then should SDM be replaced.

Scheme 11

CHART B - AIR BAG WARNING LIGHT COMES ON STEADY

When ignition switch is first turned ON, IGNITION 1 voltage is applied from RLY IGN 1 fuse REDUNDANT INDICATOR IGNITION 1 terminal No. A4 and to AIR BAG warning light which is connected to SIR indicator and terminal No. A9. SIR fuse applies voltage to IGNITION 1 input terminal No. B9. SDM responds by flashing AIR BAG warning light 7 times. If IGNITION 1 is outside of normal voltage range, AIR BAG warning light will come on steady with no DTCs.

When engine is being cranked, IGNITION 1 voltage is applied from the CRANK fuse to SDM at Crank input. SDM responds by grounding SIR indicator output until IGNITION 1 voltage is removed from Crank input. This results in AIR BAG warning light being ON during cranking. After cranking, SDM will flash AIR BAG warning light six times.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. An open in SIR fuse would cause AIR BAG warning light to come ON steady.
2. A disconnected SDM harness connector will cause warning light to come ON steady via shorting bar from terminal No. A9 to terminal No. A10.
3. This test checks for open in ground circuit to SDM.
4. This test checks for open in IGNITION 1 circuit to SDM.
5. This test checks for short from Crank input circuit to B+.
6. This test checks for short from SIR indicator circuit to ground.
7. This test checks whether a short to ground caused SIR fuse to open.
8. This test determines whether short to ground is due to short in wiring.

Scheme 12

CHART C - AIR BAG WARNING LIGHT DOES NOT COME ON

When ignition switch is first turned ON, IGNITION 1 voltage is applied from RLY IGN 1 fuse REDUNDANT INDICATOR IGNITION 1 terminal No. A4 and to AIR BAG warning light which is connected to SIR indicator and terminal No. A9. SIR fuse applies voltage to IGNITION 1 input terminal No. B9. SDM responds by flashing AIR BAG warning light 7 times. If IGNITION 1 is outside of normal voltage range, AIR BAG warning light will come on steady with no DTCs.

When engine is being cranked, IGNITION 1 voltage is applied from the CRANK fuse to SDM at Crank input. SDM responds by grounding SIR indicator output until IGNITION 1 voltage is removed from Crank input. This results in AIR BAG warning light being ON during cranking. After cranking, SDM will flash AIR BAG warning light six times.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. This test determines whether malfunction is in AIR BAG warning light circuitry or instrument cluster power feed circuitry.
2. This test confirms integrity of REDUNDANT INDICATOR IGNITION 1 circuit.
3. This tests checks for open in SIR indicator circuit, instrument cluster circuitry, and AIR BAG warning light bulb.
4. This test determines whether malfunction is due to short from SIR indicator circuit to B+ or malfunctioning instrument cluster.

When ignition switch is first turned ON, IGNITION 1 voltage is applied from RLY IGN 1 fuse REDUNDANT INDICATOR IGNITION 1 terminal No. A4 and to AIR BAG warning light which is connected to SIR indicator and terminal No. A9. SIR fuse applies voltage to IGNITION 1 input terminal No. B9. SDM responds by flashing AIR BAG warning light 7 times. If IGNITION 1 is outside of normal voltage range, AIR BAG warning light will come on steady with no DTCs.

When engine is being cranked, IGNITION 1 voltage is applied from the CRANK fuse to SDM at Crank input. SDM responds by grounding SIR indicator output until IGNITION 1 voltage is removed from Crank input. This results in AIR BAG warning light being ON during cranking. After cranking, SDM will flash AIR BAG warning light six times.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. 5) This test checks for available power to instrument cluster power feed circuit.
2. 6) This test checks for short from instrument cluster power feed circuit to ground.
3. 7) This test determines whether short to ground is due to short in wiring.
4. 8) This test checks whether malfunction is due to open power feed circuit from RLY IGN 1 fuse to instrument cluster.

Scheme 13

Scheme 14

CHART D - AIR BAG WARNING LIGHT DOES NOT COME ON STEADY DURING CRANK

When ignition switch is first turned ON, IGNITION 1 voltage is applied from RLY IGN 1 fuse REDUNDANT INDICATOR IGNITION 1 terminal No. A4 and to AIR BAG warning light which is connected to SIR indicator and terminal No. A9. SIR fuse applies voltage to IGNITION 1 input terminal No. B9. SDM responds by flashing AIR BAG warning light 7 times. If IGNITION 1 is outside of normal voltage range, AIR BAG warning light will come on steady with no DTCs.

When engine is being cranked, IGNITION 1 voltage is applied from the CRANK fuse to SDM at Crank input. SDM responds by grounding SIR indicator output until IGNITION 1 voltage is removed from Crank input. This results in AIR BAG warning light being ON during cranking. After cranking, SDM will flash AIR BAG warning light six times.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. This test checks if malfunction is due to open CRANK fuse.
2. This test checks for proper signal to Crank input during cranking.
3. This test determines whether lack of proper crank signal is due to open Crank input circuit or open power feed to CRANK fuse.
4. This test checks whether CRANK fuse is open due to short to ground in Crank input circuit.
5. This test determines whether short to ground is in wiring harness.

Scheme 15

DTC SD1015 - PASSENGER-SIDE INITIATOR CIRCUIT RESISTANCE HIGH

When ignition switch is turned ON, SDM will perform tests to diagnose critical malfunctions within itself. Upon passing these tests, IGNITION 1, 36 VLR, and deployment voltages are measured to ensure they are within normal voltage ranges. SDM then proceeds with CURRENT SOURCE DIAGNOSTICS Test, PASSENGER-SIDE LOW terminal No. A5 is grounded through a resistor and passenger current source connected to PASSENGER-SIDE HIGH terminal No. A6 allows known amount of current to flow. By monitoring voltage difference between PASSENGER-SIDE HIGH and PASSENGER-SIDE LOW SDM calculates combined resistance of passenger-side inflator module, harness wiring CKTs 1403 and 1404 and connector terminal contacts.

DTC Will Set

When combined resistance of passenger-side inflator module, harness wiring CKTs 1403 and 1404, and connector terminal contact is above a specified value. This test is run once each ignition cycle during CURRENT SOURCE DIAGNOSTICS. Test when no higher priority faults are detected during Turn ON, no higher priority faults are detected during CONTINUOUS MONITORING, no crank signal present or IGNITION 1 voltage is above specified value.

Action Taken

SDM turns on AIR BAG indicator and sets a diagnostic trouble code.

DTC Will Clear

When ignition switch is turned OFF.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. This test determines if malfunction is passenger-side inflator module circuitry or in SDM wiring harness circuitry.
2. This test checks if malfunction is due to high resistance in CKT 1403.
3. This test checks if malfunction is due to high resistance is CKT 1404.

An intermittent condition is likely to be caused by a poor connection at passenger-side inflator module harness connector terminal Nos. A or B, SDM terminal Nos. A5 or A6, or a poor wire to terminal connection in CKT 1403 or CKT 1404. The test for this diagnostic trouble code is only run while AIR BAG indicator is performing BULB TEST, unless DTC SD1017 or DTC SD1026 is detected. When scan tool CLEAR CODES command is issued and the malfunction is still present, DTC will not reappear until next ignition cycle.

Scheme 16

DTC SD1016 - PASSENGER-SIDE INITIATOR CIRCUIT RESISTANCE LOW

When ignition switch is turned ON, SDM will perform tests to diagnose critical malfunctions within itself. Upon passing these tests, IGNITION 1, 36 VLR, and deployment voltages are measured to ensure they are within normal voltage ranges. SDM then proceeds with CURRENT SOURCE DIAGNOSTICS Test, PASSENGER-SIDE LOW terminal No. A5 is grounded through a resistor and passenger current source connected to PASSENGER-SIDE HIGH terminal No. A6 allows known amount of current to flow. By monitoring voltage difference between PASSENGER-SIDE HIGH and PASSENGER-SIDE LOW SDM calculates combined resistance of passenger-side inflator module, harness wiring CKTs 1403 and 1404 and connector terminal contacts.

When combined resistance of passenger-side inflator module, harness wiring CKTs 1403 and 1404, and connector terminal contact is below a specified value. This test is run once each ignition cycle during CURRENT SOURCE DIAGNOSTICS. Test when no higher priority faults are detected during turn ON, no higher priority faults are detected during CONTINUOUS MONITORING, no crank signal present or IGNITION 1 voltage is above specified value.

SDM turns on AIR BAG indicator and sets a diagnostic trouble code.

When ignition switch is turned OFF.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. DTC SD1016 and SD1022 will set simultaneously when DRIVER-SIDE HIGH circuit is shorted to PASSENGER-SIDE HIGH circuit due to parallel current paths.
2. This test determines if malfunction is in passenger-side inflator module circuitry or SDM wiring harness circuitry.
3. This test checks for short from PASSENGER-SIDE HIGH circuit to PASSENGER-SIDE LOW circuit.
4. This test checks for short from PASSENGER-SIDE HIGH circuit to DRIVER-SIDE LOW circuit.

An intermittent condition is likely to be caused by a short between CKT 1403 or CKT 347, CKT 348 or CKT 1404, or a malfunctioning shorting bar on passenger-side inflator module which would require replacement of passenger-side inflator module. The test for this diagnostic trouble code is only run while AIR BAG indicator is performing BULB TEST, unless DTC SD1017 or SD1026 is detected. When scan tool CLEAR CODES command is issued and the malfunction is still present, DTC will not reappear until next ignition cycle.

Scheme 17

DTC SD1017 - PASSENGER-SIDE INITIATOR CIRCUIT OPEN

When ignition switch is turned ON, SDM will perform tests to diagnose critical malfunctions within itself. Upon passing these tests, IGNITION 1, 36 VLR, and deployment voltages are measured to ensure they are within normal voltage ranges. SDM then proceeds with CURRENT SOURCE DIAGNOSTICS Test, PASSENGER-SIDE LOW terminal No. A5 is grounded through a resistor and passenger current source connected to PASSENGER-SIDE HIGH terminal No. A6 allows known amount of current to flow. After CURRENT SOURCE DIAGNOSTICS are completed the SDM removes the low resistance ground from PASSENGER-SIDE LOW and switches the passenger current source at PASSENGER-SIDE HIGH. SDM then measures voltage at PASSENGER-SIDE HIGH and PASSENGER-SIDE LOW during CONTINUOUS MONITORING. By monitoring voltage difference between PASSENGER-SIDE HIGH and PASSENGER-SIDE LOW SDM calculates combined resistance of passenger-side inflator module, harness wiring CKTs 1403 and 1404 and connector terminal contacts.

When voltage difference between PASSENGER-SIDE HIGH terminal No. A6 and PASSENGER-SIDE LOW terminal No. A5 is above or equal to a specified value for 500 milliseconds during CURRENT SOURCE DIAGNOSTICS or CONTINUOUS MONITORING.

SDM turns on AIR BAG indicator and sets a diagnostic trouble code.

When voltage difference between PASSENGER-SIDE HIGH terminal No. A6 and PASSENGER-SIDE LOW terminal No. A5 is below a specified value for 500 milliseconds during CONTINUOUS MONITORING.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. This test determines if malfunction is passenger-side inflator module circuitry or in SDM wiring harness circuitry.
2. This test checks if malfunction is due to high resistance in CKT 1403.
3. This test checks if malfunction is due to high resistance is CKT 1404.

An intermittent condition is likely to be caused by a poor connection at passenger-side inflator module harness connector terminal Nos. A or B, SDM terminal Nos. A5 or A6, or an open in CKT 1403 or CKT 1404.

Scheme 18

DTC SD1021 - DRIVER-SIDE INITIATOR CIRCUIT RESISTANCE HIGH

When ignition switch is turned ON, SDM will perform tests to diagnose critical malfunctions within itself. Upon passing these tests, IGNITION 1, 36 VLR, and deployment loop voltages are measured to ensure they are within normal voltage ranges. The SDM then proceeds with CURRENT SOURCE DIAGNOSTICS Test. DRIVER-SIDE LOW terminal No. A2 is grounded through a resistor and the driver current source connected to DRIVER-SIDE HIGH terminal No. A1 allows a known amount of current to flow. By monitoring the voltage difference between DRIVER-SIDE HIGH and DRIVER-SIDE LOW the SDM calculates the combined resistance of the driver-side inflator module, SIR coil assembly, harness wiring CKTs 347 and 348 and connector terminal contact.

When the combined resistance of the driver-side inflator module, SIR coil assembly, harness wiring CKTs 347 and 348 and connector terminal contact is above a specified value. This test is run during CURRENT SOURCE DIAGNOSTICS Test when

1. 1) No higher priority faults are detected during Turn ON.
2. 2) No higher priority faults are detected during CONTINUOUS MONITORING.
3. 3) No Crank signal present.
4. 4) IGNITION 1 voltage is above a specified value.

SDM turns on AIR BAG indicator and sets a diagnostic trouble code.

When ignition switch is turned OFF.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. This test determines if malfunction is driver-side inflator module circuitry or in SDM wiring harness circuitry.
2. This test checks if malfunction is due to high resistance in CKT 347.
3. This test checks if malfunction is due to high resistance is CKT 348.
4. This test determines if malfunction is in driver-side inflator module or SIR coil assembly.

An intermittent condition is likely to be caused by poor connection at terminal Nos. A or B of SIR coil connector at base of steering column, terminal Nos. A or B of driver-side inflator module connector at top of steering column, SDM terminal Nos. A1 or A2 or a poor wire to terminal connection in CKT 347 or CKT 348. The test for this diagnostic trouble code is only run while AIR BAG indicator is performing BULB TEST, unless DTC SD1017 or DTC SD1026 is detected. When scan tool CLEAR CODES command is issued and malfunction is still present, DTC will not reappear until next ignition cycle.

Scheme 19

DTC SD1022 - DRIVER-SIDE INITIATOR CIRCUIT RESISTANCE LOW

When ignition switch is turned ON, SDM will perform tests to diagnose critical malfunctions within itself. Upon passing these tests, IGNITION 1, 36 VLR, and deployment loop voltages are measured to ensure they are within normal voltage ranges. The SDM then proceeds with CURRENT SOURCE DIAGNOSTICS Test. DRIVER-SIDE LOW terminal No. A2 is grounded through a resistor and the driver current source connected to DRIVER-SIDE HIGH terminal No. A1 allows a known amount of current to flow. By monitoring the voltage difference between DRIVER-SIDE HIGH and DRIVER-SIDE LOW the SDM calculates the combined resistance of the driver-side inflator module, SIR coil assembly, harness wiring CKTs 347 and 348 and connector terminal contact.

When the combined resistance of the driver-side inflator module, SIR coil assembly, harness wiring CKTs 347 and 348 and connector terminal contact is above a specified value. This test is run during CURRENT SOURCE DIAGNOSTICS Test when

1. 1) No higher priority faults are detected during Turn ON.
2. 2) No higher priority faults are detected during CONTINUOUS MONITORING.
3. 3) No Crank signal present.
4. 4) IGNITION 1 voltage is above a specified value.

SDM turns on AIR BAG indicator and sets a diagnostic trouble code.

When ignition switch is turned OFF.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. DTC SD1016 and DTC SD1022 will set simultaneously when DRIVER-SIDE HIGH circuit is shorted to PASSENGER-SIDE HIGH circuit due to parallel current paths.
2. This test determines if malfunction is in driver-side inflator module circuitry or SDM wiring harness circuitry.
3. This test checks for short from DRIVER-SIDE HIGH circuit to DRIVER-SIDE LOW circuit.
4. This test checks for short from DRIVER-SIDE HIGH circuit to PASSENGER-SIDE LOW circuit.
5. This test determines if malfunction is in driver-side inflator module or SIR coil assembly.

An intermittent condition is likely to be caused by a short between CKT 347 and CKT 348, 1403, or 1404, or a malfunctioning shorting bar on driver-side inflator module or SIR coil assembly which would require replacement of component. The test for this diagnostic trouble code is only run while AIR BAG indicator is performing BULB TEST, unless DTC SD1017 or DTC SD1026 is detected. When scan tool CLEAR CODES command is issued and malfunction is still present, DTC will not reappear until next ignition cycle.

Scheme 20

DTC SD1024 - INITIATOR CIRCUIT VOLTAGE LOW

When ignition switch is turned ON, SDM will perform tests to diagnose critical malfunctions within itself. Upon passing these tests, IGNITION 1, 36 VLR, and deployment loop voltages are measured to ensure they are within normal voltage ranges. The SDM monitors the voltages at DRIVER-SIDE LOW terminal No. A2 and PASSENGER-SIDE LOW terminal No. A5 to detect shorts to ground in inflator module circuits. The service wait time is 10 minutes. See DISABLING SYSTEM before replacing SRS components.

When the 36 VLR power supply in SDM is within normal operating voltage range and at least one of the two inflator modules is not open. The voltage of both DRIVER-SIDE LOW and PASSENGER-SIDE LOW is below a specified value for 500 milliseconds. This test is run during Turn ON tests and every 100 milliseconds during CONTINUOUS MONITORING.

SDM turns on AIR BAG indicator and sets DTC.

When voltage measured at DRIVER-SIDE LOW and PASSENGER-SIDE LOW are above specified value for 500 milliseconds.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. This test determines if malfunction is in driver-side inflator module circuitry.
2. This test determines if malfunction is in passenger-side inflator module circuitry.
3. This test checks for short from DRIVER-SIDE HIGH to ground.
4. This test checks for short from DRIVER-SIDE LOW to ground.
5. This test checks for short from PASSENGER-SIDE LOW to ground.
6. This test checks for short from PASSENGER-SIDE HIGH to ground.

An intermittent condition is likely to be caused by a short to ground in the inflator module circuits. Inspect CKTs 347, 348, 1403 and 1404 carefully for cutting or chafing. If the wiring pigtail of SIR coil assembly, driver-side inflator module or passenger-side inflator module is damaged the component must be replaced.

Scheme 21

Scheme 22

DTC SD1025 - INITIATOR CIRCUIT SHORT TO IGNITION

When ignition switch is turned ON, SDM will perform tests to diagnose critical malfunctions within itself. Upon passing these tests, IGNITION 1, 36 VLR, and deployment loop voltages are measured to ensure they are within normal voltage ranges. The SDM monitors the voltages at DRIVER-SIDE LOW terminal No. A2 and PASSENGER-SIDE LOW terminal No. A5 to detect shorts to B+ in inflator module circuits. The service wait time is 10 minutes. See DISABLING SYSTEM before replacing SRS components.

When the 36 VLR power supply in SDM is in normal operating voltage range and neither of two inflator modules is open. Then voltage measured at DRIVER-SIDE LOW and PASSENGER-SIDE LOW is within specified range. Once conditions are met SDM will ground DRIVER-SIDE LOW and PASSENGER-SIDE LOW through resistor and check IGNITION 1 is in normal operating voltage range. When all previous conditions are met and voltage measured at DRIVER-SIDE LOW and PASSENGER-SIDE LOW is above specified value.

SDM turns on AIR BAG indicator and sets DTC SD1025 and DTC SD1071.

When malfunction is no longer occurring and ignition switch is turned OFF, however, DTC SD1071 will remain current.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. This test determines if malfunction is in driver-side inflator module circuitry.
2. This test determines if malfunction is in passenger-side inflator module circuitry.
3. This test checks for short from DRIVER-SIDE HIGH to B+.
4. This test checks for short from DRIVER-SIDE LOW to B+.
5. This test checks for short from PASSENGER-SIDE HIGH to B+.
6. This test checks for short from PASSENGER-SIDE LOW to B+.

An intermittent condition is likely to be caused by a short to B+ in inflator module circuit. A DTC SD1025 history would be accompanied by DTC SD1071 current. Inspect circuits and components indicated on DTC SD1025 charts to ensure replacement SDM will not be damaged.

Scheme 23

Scheme 24

DTC SD1026 - DRIVER-SIDE INITIATOR CIRCUIT OPEN

When ignition switch is turned ON, SDM will perform tests to diagnose critical malfunctions within itself. Upon passing these tests, IGNITION 1, 36 VLR, and deployment voltages are measured to ensure they are within normal voltage ranges. SDM then proceeds with CURRENT SOURCE DIAGNOSTICS Test, DRIVER-SIDE LOW terminal No. A2 is grounded through a resistor and passenger current source connected to DRIVER-SIDE HIGH terminal No. A1 allows known amount of current to flow. After CURRENT SOURCE DIAGNOSTICS are completed the SDM removes the low resistance ground from DRIVER-SIDE LOW and switches the passenger current source at DRIVER-SIDE HIGH. SDM then measures voltage at DRIVER-SIDE HIGH and DRIVER-SIDE LOW during CONTINUOUS MONITORING. By monitoring voltage difference between DRIVER-SIDE HIGH and DRIVER-SIDE LOW SDM calculates combined resistance of passenger-side inflator module, harness wiring CKTs 347 and 348 and connector terminal contacts.

When voltage difference between DRIVER-SIDE HIGH terminal No. A1 and DRIVER-SIDE LOW terminal No. A2 is above or equal to a specified value for 500 milliseconds during CURRENT SOURCE DIAGNOSTICS or CONTINUOUS MONITORING.

SDM turns on AIR BAG indicator and sets a diagnostic trouble code.

When voltage difference between DRIVER-SIDE HIGH terminal No. A1 and DRIVER-SIDE LOW terminal No. A2 is below a specified value for 500 milliseconds during CONTINUOUS MONITORING.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. This test determines if malfunction is driver-side inflator module circuitry or in SDM wiring harness circuitry.
2. This test checks if malfunction is due to high resistance in CKT 347.
3. This test checks if malfunction is due to high resistance is CKT 348.
4. This test determines if malfunction is in driver-side inflator module or SIR coil assembly.

An intermittent condition is likely to be caused by a poor connection at driver-side inflator module terminal Nos. A or B, SIR coil assembly terminal Nos. A or B, SDM terminal Nos. A1 or A2, or an open in CKT 347 or CKT 348.

Scheme 25

DTC SD1035 - DISCRIMINATING SENSOR OPEN OR SHORT TO GROUND

When ignition switch is turned ON, SDM will perform tests to diagnose critical malfunctions within itself. Upon passing these tests, IGNITION 1, 36 VLR, and deployment loop voltages are measured to ensure they are within normal voltage ranges. The SDM then proceeds with CURRENT SOURCE DIAGNOSTICS followed by CONTINUOUS MONITORING. SDM supplies REFERENCE VOLTAGE at terminal No. B6 and measures voltage at SENSOR SIGNAL terminal No. B5. During normal operation voltage measured at SENSOR SIGNAL will be about one half REFERENCE VOLTAGE.

When voltage measured at SENSOR SIGNAL terminal No. B5 is below specified value for 500 milliseconds during CONTINUOUS MONITORING.

SDM turns on AIR BAG indicator and sets a diagnostic trouble code.

When voltage measured at SENSOR SIGNAL terminal No. B5 is in normal range for 500 milliseconds during CONTINUOUS MONITORING.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. This test checks proper resistance of forward discriminating sensor.
2. This test checks for open in REFERENCE VOLTAGE circuit.
3. This test checks for open in SENSOR SIGNAL circuit.
4. This test checks for short from REFERENCE VOLTAGE to ground.
5. This test checks for short from SENSOR SIGNAL to ground.

An intermittent condition is likely to be caused by a poor connection to forward discriminating sensor at terminal Nos. A or B, poor connection to SDM at terminal Nos. B5 or B6, a short to ground or open in CKT 349 or 1851.

Scheme 26

DTC SD1036 - DISCRIMINATING SENSOR CLOSED OR SHORT TO IGNITION

When ignition switch is turned ON, SDM will perform tests to diagnose critical malfunctions within itself. Upon passing these tests, IGNITION 1, 36 VLR, and deployment loop voltages are measured to ensure they are within normal voltage ranges. The SDM then proceeds with CURRENT SOURCE DIAGNOSTICS followed by CONTINUOUS MONITORING. SDM supplies REFERENCE VOLTAGE at terminal No. B6 and measures voltage at SENSOR SIGNAL terminal No. B5. During normal operation voltage measured at SENSOR SIGNAL will be about one half REFERENCE VOLTAGE.

When voltage measured at SENSOR SIGNAL terminal No. B5 is below specified value for 500 milliseconds during CONTINUOUS MONITORING.

SDM turns on AIR BAG indicator and sets a diagnostic trouble code.

When voltage measured at SENSOR SIGNAL terminal No. B5 is in normal range for 500 milliseconds during CONTINUOUS MONITORING.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. This test checks proper resistance of forward discriminating sensor.
2. This test checks for short in REFERENCE VOLTAGE circuit to SENSOR SIGNAL circuit.
3. This test checks for REFERENCE VOLTAGE to B+.
4. This test checks for short from SENSOR SIGNAL to B+.

An intermittent condition is likely to be caused by a short from CKT 349 to CKT 1851, a short from CKT 349 to B+, or a short from CKT 1851 to B+.

Scheme 27

DTC SD1051 - FRONTAL CRASH DETECTED

SDM contains a sensing device which converts vehicle velocity changes to an electrical signal. The electrical signal is processed by the SDM and compared to a value stored in memory. When signal exceeds stored value, additional signal processing is performed and signals are compared to signals stored in memory. When 2 of the signals exceed stored values, SDM will cause sufficient current to flow through inflator modules deploying air bags and causing DTC to set.

When SDM detects a frontal crash, up to 30 degrees off centerline of vehicle, of sufficient force to warrant deployment of air bags.

SDM turns on AIR BAG indicator, records CRASH DATA and sets a diagnostic trouble code.

When scan tool CLEAR CODES command is received by SDM.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

1. If inflator module(s) has not deployed, DTC SD1051 may have set falsely.
2. If DTC SD1051 has set with no signs of frontal impact, diagnostic trouble code has set falsely.
3. This test checks for an SDM malfunction setting the diagnostic trouble code.
4. This test determines if DTC was set inadvertently during diagnosis.

Scheme 28

DTC SD1052 - DATA AREA FULL

When SDM detects a frontal crash, up to 30 degrees off centerline of vehicle, of sufficient force to warrant deployment of air bags, DTC SD1051 will set. SDM will record SIR system and vehicle status in EEPROM. DTC SD1052 will set when SDM has stored information for two frontal crash events.

When SDM attempts to store frontal crash information and finds EEPROM data area full. This test is run each time SDM stores or attempts to store information for frontal crash event and also during Turn ON tests.

SDM turns on AIR BAG indicator, records CRASH DATA and sets a diagnostic trouble code.

When scan tool CLEAR CODES command is received by SDM. If, at next ignition ON after receiving CLEAR CODES command, SDM detects data area full, history diagnostic trouble code is set. This allows AIR BAG warning light to illuminate should any additional malfunctions be detected.

Scheme 29

DTC SD1055 - SDM CALIBRATION MIS-MATCH

The Body Control Module (PZM) sends a message over the UART data line containing identification information. The PZM message includes vehicle body type identification information. If message sent from PZM does not match calibration information stored in SDM, DTC SD1055 is set.

When identification information message sent over UART from PZM does not match identification information stored in SDM.

SDM turns on AIR BAG indicator and sets a diagnostic trouble code.

The ignition switch is turned OFF. After correcting the SIR CAL PZS33 vehicle selection in the PZM OVERRIDE mode of the On-Board Diagnostics, turn ignition OFF and then ON to clear DTC SD1055. Clear history DTC using TECH 1 or On-Board Diagnostics, SDM CLEAR CODES command.

Scheme 30

DTC SD1061 - AIR BAG WARNING LIGHT CIRCUIT FAILURE

When the ignition key is first turned ON, battery voltage is applied to AIR BAG warning light and to IGNITION 1 input terminal No. B9. SDM responds by flashing AIR BAG indicator 7 times alternating between the primary and redundant light drivers. SDM monitors light driver output by comparing output of SIR indicator terminal No. A9 to microprocessor commanded state. If IGNITION 1 voltage to SDM is outside normal operating range and output state does not match commanded state of light driver for 400 milliseconds, DTC SD1061 will set.

When IGNITION 1 voltage is above specified value and output state at SIR indicator terminal No. A9 does not match commanded state of light driver for 400 milliseconds. This test runs every 100 milliseconds during CONTINUOUS MONITORING.

SDM attempts to Turn ON AIR BAG indicator and sets a diagnostic trouble code.

When ignition switch is turned OFF.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

When SDM is configured for serial data controlled warning light, DTC SD1061 will set. Clearing SIR diagnostic trouble codes will reset SDM allowing it to control AIR BAG warning light.

See SIR DIAGNOSTIC SYSTEM CHECK and refer to CHARTS B and C to diagnose warning light circuit malfunctions.

Scheme 31

DTC SD1062 - REDUNDANT AIR BAG WARNING LIGHT CIRCUIT FAILURE

When the ignition key is first turned ON, battery voltage is applied to AIR BAG warning light and to IGNITION 1 input terminal No. B9. SDM responds by flashing AIR BAG indicator 7 times alternating between the primary and redundant light drivers. SDM monitors light driver output by comparing output of SIR indicator terminal No. A9 to microprocessor commanded state. If IGNITION 1 voltage to SDM is outside normal operating range and output state does not match commanded state of light driver for 400 milliseconds, DTC SD1062 will set.

When IGNITION 1 voltage is above specified value and output state at SIR indicator terminal No. A9 does not match commanded state of light driver for 400 milliseconds. This test runs every 100 milliseconds during CONTINUOUS MONITORING.

SDM attempts to Turn ON AIR BAG indicator and sets a diagnostic trouble code.

When ignition switch is turned OFF.

Note. Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

This test determines if malfunction is due to open in REDUNDANT INDICATOR IGNITION 1 circuit.

An intermittent condition is likely to be caused by poor connection to SDM at terminal No. A4 or open in CKT 1039B. A poor REDUNDANT INDICATOR GROUND connection to SDM would set DTC SD1062. SDM mounting surface should be free of any dirt or foreign material and that it is properly fastened to ensure good REDUNDANT INDICATOR GROUND.

Scheme 32

DTC SD1071 - INTERNAL SDM FAULT

DTC SD1071 indicates potential internal SDM malfunction and will set if any of the following conditions are detected

1. 1) 36 VLR Voltage out of normal operating range.
2. 2) Crash data recording reserve voltage discharge time failure for 3 consecutive ignition cycles.
3. 3) Calculated checksum for internal memory does not match stored value.
4. 4) Voltage measured at DRIVER-SIDE LOW and PASSENGER-SIDE LOW are too high.
5. 5) Sensing device inside SDM which converts vehicle velocity changes to electrical signal is malfunctioning.
6. 6) Driver current source and/or passenger current source is malfunctioning.
7. 7) Temporary memory storage area is malfunctioning.
8. 8) SDM unable to read from or write to EEPROM.
9. 9) Arming sensor inside SDM is not closed during deployment event.
10. 10) DTC SD1025 has been set.

DTC will set when any of the indicated malfunctions are detected by the SDM.

SDM attempts to Turn ON AIR BAG indicator and sets a diagnostic trouble code.

A scan tool CLEAR CODES command is received by SDM. Some of indicated malfunctions will only allow AIR BAG indicator to go out briefly then come back on.

See SIR DIAGNOSTIC SYSTEM CHECK .

Scheme 33

SIR System Wiring Diagram (Concours, DeVille, Eldorado, & Seville). Scheme 34

See also:
• DISABLING SYSTEM
• SYSTEM OPERATION CHECK
• DISPOSAL PROCEDURES
• SPECIAL TOOLS
• AIR BAG MODULE
• AIR BAG MODULES
• SERVICE PRECAUTIONS
• TORQUE SPECIFICATIONS
• ACTIVATING SYSTEM
• SIR DIAGNOSTIC SYSTEM CHECK