Air Bag System Testing

Introduction

This procedure is derived from the Porsche factory airbag system diagnostics procedure. It covers reading the fault codes stored in the airbag system's memory using the blink-code method.

The airbag system continuously self-monitors and stores faults. Any fault triggers the "Airbag" warning light on the instrument cluster. When the ignition is turned on and when the engine is started, the Airbag light illuminates and remains lit for 5 seconds. If no faults are detected, the light extinguishes.

Testing requires a test rig to apply a ground to the airbag test connector. See ELECT-12 (Air Bag Warning Light Reset) for test rig fabrication instructions.

After the ground is applied to the test connector, the Airbag light blinks in coded sequences to indicate stored faults. It takes approximately 2 minutes to complete the full fault readout, so the ignition must remain ON for at least 2 minutes during the test.

Tools

• Test rig (per ELECT-12)
• Pen and paper for recording fault codes

Procedure

1. Turn the ignition switch OFF.

2. Connect the test rig from the airbag Molex test connector to ground.

3. Depress and hold the switch/pushbutton on the test rig.

4. Turn the ignition switch ON.

5. Release the test rig pushbutton 3 seconds after the ignition switch is turned on.

6. Count and record the lamp blink codes. The sequence runs as follows:

   a. 5-second lamp test (light illuminates for 5 seconds). b. Light flashes 1 or more times to indicate the number of faults. c. 3-second pause, then fault codes begin. d. Light flashes 1–4 times to indicate the fault code group. e. 3-second pause. f. Light flashes 1–4 times to indicate the line in the fault table. g. 3-second pause. h. Light flashes 1–4 times to indicate the column in the fault table. i. 3-second pause. j. Light flashes 1 or 2 times:

   • 1 flash = short-time fault
   • 2 flashes = long-time fault k. 3-second pause, then next fault code sequence begins. l. Light remains lit at the end of the test.

7. Using the lamp code table, determine the system faults and take corrective action per the "Correcting Faults" section below.

8. After all testing and repairs are complete, reset the airbag warning light per ELECT-12.

The flash code test may be repeated as often as needed.

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Lamp Code Table

The fault code is identified by combining the group, line, and column numbers from the blink sequence. The grid below maps those combinations to hex codes.

Group 1:

	Column 1	Column 2	Column 3	Column 4
Line 1	01	11	21	31
Line 2	05	—	25	—
Line 3	09	19	29	—
Line 4	0D	1D	2D	—

Group 2:

	Column 1	Column 2	Column 3	Column 4
Line 1	02	12	22	32
Line 2	06	—	26	—
Line 3	0A	1A	2A	—
Line 4	0E	1E	2E	—

Group 3:

	Column 1	Column 2	Column 3	Column 4
Line 1	03	13	23	33
Line 2	07	17	27	—
Line 3	0B	1B	2B	—
Line 4	—	1F	2F	—

Group 4:

	Column 1	Column 2	Column 3	Column 4
Line 1	04	14	24	34
Line 2	08	18	28	—
Line 3	0C	1C	2C	—
Line 4	—	20	30	—

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Air Bag Fault Code Table

Hex Code	Fault Description	Fault Condition
01	Front Sensor Left	Closed 1 time
02	Front Sensor Left	Closed several times
03	Front Sensor Right	Closed 1 time
04	Front Sensor Right	Closed several times
05	Front Sensor Left	Closed permanently
06	Front Sensor Right	Closed permanently
07	Front Sensor Lead Left	Leaks against positive
08	Front Sensor Lead Right	Leaks against positive
09	Front Sensor Lead Left	Leaks against ground
0A	Front Sensor Lead Right	Leaks against ground
0B	Front Sensor Lead Left	Short circuit against positive
0C	Front Sensor Lead Right	Short circuit against positive
0D	Front Sensor Lead Left	Short circuit against ground
0E	Front Sensor Lead Right	Short circuit against ground
11	Front Sensor Lead Left	Break
12	Front Sensor Lead Right	Break
13	Front Sensor Lead Left	Excessive resistance
14	Front Sensor Lead Right	Excessive resistance
17	Ignition Capacitor 1	Insufficient capacitance
18	Ignition Capacitor 2	Insufficient capacitance
19	Transition resistance to Ignition Capacitor 1	Excessive
1A	Transition resistance to Ignition Capacitor 1	Excessive
1B	Ignition Pill Circuit 1	Leak against positive
1C	Ignition Pill Circuit 2	Leak against positive
1D	Ignition Pill Circuit 3	Leak against positive
1E	Ignition Pill Circuit 1	Short circuit against positive
1F	Ignition Pill Circuit 2	Short circuit against positive
20	Ignition Pill Circuit 3	Short circuit against positive
21	Ignition Pill Circuit 1	Leak against ground
22	Ignition Pill Circuit 2	Leak against ground
23	Ignition Pill Circuit 3	Leak against ground
24	Ignition Pill Circuit 1	Short circuit against ground
25	Ignition Pill Circuit 2	Short circuit against ground
26	Ignition Pill Circuit 3	Short circuit against ground
27	Ignition Pill Circuit 1	Break
28	Ignition Pill Circuit 2	Break
29	Ignition Pill Circuit 3	Break
2A	Ignition Pill Circuit 1	Insufficient resistance
2B	Ignition Pill Circuit 2	Insufficient resistance
2C	Ignition Pill Circuit 3	Insufficient resistance
2D	Ignition Pill Circuit 1	Excessive resistance
2E	Ignition Pill Circuit 2	Excessive resistance
2F	Ignition Pill Circuit 3	Excessive resistance
30	Failure Warning Lamp	Short circuit
31	Failure Warning Lamp	Broken filament
32	Control Unit	Internal fault
33	Firing Order Correct	—
34	Ignition Current Flowed	—

Circuit assignments:

• Ignition Pill Circuit 1 = Driver's airbag
• Ignition Pill Circuits 2 and 3 = Passenger's airbag

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Correcting Faults

Faults 01–06

Replace the left or right front sensor.

Faults 07–0E

Check the front sensor with an ohmmeter:

1. Terminals 1 and 2: should read 10 kΩ.
2. Terminals 2 and 3: should read 0 Ω.

If readings are correct, erase the fault memory. If the fault persists, replace the control unit. If readings are incorrect, replace the front sensor.

Fault 11 or 12

Check the front sensor plug connection for proper tightness. Then check the front sensor with an ohmmeter (see Faults 07–0E).

If the ohmmeter shows infinite resistance for point 1 or 2, replace the front sensor. If readings are in spec, replace the control unit.

Fault 13 or 14

Check the front sensor with an ohmmeter (see Faults 07–0E). If the front sensor checks out, replace the control unit.

Faults 17–1A

Replace the control unit.

Faults 1B, 1E, 21, 24

Try installing a new contact unit. Reset the airbag warning light (ELECT-12) and turn the ignition on. If the fault persists, try installing an airbag unit. Reset and re-test. If the fault still persists, replace the control unit.

Faults 1C, 1D, 1F, 20, 22, 23, 25, 26

Try installing a new airbag unit. Reset the airbag warning light (ELECT-12) and turn the ignition on. If the fault persists, replace the control unit.

Fault 27

Check the plug connection to the airbag unit and the contact unit for tightness. If connections are tight, try installing a new contact unit. Reset and re-test. If the fault persists, try installing an airbag unit. Reset and re-test. If the fault still persists, replace the control unit.

Fault 28 or 29

Check the plug connection to the airbag unit for tightness. If tight, try installing a new airbag unit. Reset and re-test. If the fault persists, replace the control unit.

Faults 2A, 2B, 2C

Try installing an airbag unit. Reset and re-test. If the fault persists, replace the control unit.

Fault 2D

Replace the contact unit. Check plug contacts on the airbag unit and contact unit for corrosion. If contacts are clean, try installing a new airbag unit. Reset and re-test. If the fault persists, replace the control unit.

Fault 2E or 2F

Check plug contacts on the airbag unit and contact unit for corrosion. If contacts are clean, try installing a new airbag unit. Reset and re-test. If the fault persists, replace the control unit.

Faults 30 and 31

The central warning lamp and belt symbol will continue to illuminate after the airbag warning fails. Remove and inspect the control lamp and replace if necessary. Check the wiring harness for damage and replace the control unit if needed.

Fault 32

Replace the control unit.

Faults 33 and 34

These codes appear only after an accident with airbag activation. All airbag system components must be replaced.