Code No.1A Front impact sensor (LH) circuit-short
Code No.1B Front impact sensor (LH) circuit-open
Code No.1C Front impact sensor (LH) short-circuited to power supply
Code No.1D Front impact sensor (LH) short-circuited to earth
Code No.2A Front impact sensor (RH) circuit-short
Code No.2B Front impact sensor (RH) circuit-open
Code No.2C Front impact sensor (RH) short-circuited to power supply
Code No.2D Front impact sensor (RH) short-circuited to earth

OPERATION

When the left and right front impact sensors detect a collision, the switches inside the sensors turn ON.
SRS-ECU judges how severe a collision is by detecting signals from the front impact sensors and the front air bag analogue G-sensor. If the impact is over a predetermined level, the SRS-ECU sends an ignition signal. At this time, if the front air bag safing G-sensor is on, the SRS air bag will inflate.

DIAGNOSIS CODE SET CONDITIONS

These diagnosis codes are set if these are abnormal resistance between the input terminals of the front impact sensors.
The most likely causes for these codes to be set are shown in the table below:

Code No.	Trouble causes
1A	Left front impact sensor or its wiring shorted
1B	Left front impact sensor or wiring open circuit
1C	Short to the power supply in the left front impact sensor harness
1D	Short to body earth in the left front impact sensor harness
2A	Right front impact sensor or its wiring shorted
2B	Right front impact sensor or wiring open circuit
2C	Short to the power supply in the right front impact sensor harness
2D	Short to body earth in the right front impact sensor harness

PROBABLE CAUSE

Damaged harness wires and connectors
Front impact sensor failed
Malfunction of the SRS-ECU

DIAGNOSIS PROCEDURE

Step 1. Check the front impact sensor.

Refer to

.

Q. Is the check result normal?

	Go to Step 2.

	Replace the front impact sensor (Refer to ).

Step 2. Resistance measurement at the SRS-ECU connector C-147.

(1)Disconnect the negative battery terminal.

(2)Disconnect SRS-ECU connector C-147.

(3)

caution

Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.

Take the measurements below at harness-side connector C-147.

Resistance between terminals 1 and 2 as well as 3 and 4.

NG: 2 ohms or less (short circuit) or 2 megaohms or more (open circuit)

(4)

Continuity between terminals 1, 2, 3, 4 and body earth

OK: No continuity

Q. Is the check result normal?

Go to Step 3.

Go to Step 4.

Step 3. Voltage measurement at the SRS-ECU connector C-147.

(1)Disconnect the negative battery terminal.

(2)Disconnect SRS-ECU connector C-147.
(3)Connect the negative battery terminal.
(4)Turn the ignition switch to the "ON" position.

(5)

caution

Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.

Take the measurements below at harness-side connector C-147.
(6)

Voltage between terminals 1, 2, 3, 4 and body earth

OK: 0V

Q. Is the check result normal?

Go to Step 5.

Go to Step 4.

Step 4. Check the wiring harness between the front impact sensor (RH) connector A-30 (terminals 1 and 2) and SRS-ECU connector C-147 (terminals 1 and 2) as well as between front impact sensor (LH) connector A-22 (terminals 1 and 2) and SRS-ECU connector C-147 (terminals 3 and 4).

note

Prior to the wiring harness inspection, check intermediate connectors C-124, and repair if necessary.

(1)

Check the front impact sensor output line for open or short circuit.

Q. Is the check result normal?

Go to Step 5.

Repair the wiring harness.

Step 5. Check whether the diagnosis code is reset.

Check again if the diagnosis code is set.

Q. Is diagnosis code 1A, 1B, 1C, 1D, 2A, 2B, 2C or 2D set?

	Replace the SRS-ECU (Refer to ).

	An intermittent malfunction is suspected (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points ).