Inspection Procedure 25: Blower Switch System <Cooler, Manual A/C>

OPERATION

The battery voltage is applied to the engine-ECU connector terminal BFAN from the blower switch.

FUNCTION

When the blower fan is turned ON and the battery voltage is applied to the engine-ECU, the engine-ECU increases the idle speed.

PROBABLE CAUSES

Failed A/C system
Open/short circuit or harness damage in blower switch circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Perform voltage measurement at engine-ECU connector.

Measure engine-ECU terminal voltage.
Engine: Idling
Voltage between terminal BFAN and body earth.

OK:
System voltage (when blower speed selection dial is "3 (MH)" position)
1 V or less (when blower switch is except "3 (MH)" position)

Q. Is the check result normal?

	Go to Step 2.

	Check A/C system (Refer to GROUP 55A - Troubleshooting - Check Chart for Trouble Symptoms) <Manual A/C>.

STEP 2. Check harness between blower switch connector terminal and engine-ECU connector terminal BFAN.

Check output line for short circuit.

Q. Is the check result normal?

	Go to Step 3.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 3. Check the trouble symptoms.

Q. Does the trouble symptom persist?

	Replace the engine-ECU.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).