B1208 Intake Potentiometer Open (Low) - Automotive Repair Guides & Equipment

COMPONET LOCATION

GENERAL DESCRIPTION

The actuator contains a motor that changes intake door position and a potentiometer that monitors position of the door. When the driver changes the air intake switch, the ECU operates intake door motor to turn the intake door to the intended position. (in the FRESH mode, the intake door is closed. In REC mode, the intake door is opened) During operation the potentiometer delivers an intake door position to the A/C ECU.

DTC DESCRIPTION

The Airconditioner Control Module sets DTC B1208 if the Feed Back signal of Intake Actuator has been detected open or below 0.1V for 0.3 seconds.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible Cause

DTC Strategy

Voltage check

1.	Poor connection of connected part

2.	Open circuit in signal/power harness

3.	Short circuit in signal/power harness

4.	Faulty Intake potentiometer

Enable Conditions

IG KEY ON

Threshold value

Feedback circuit has been detected open or below 0.1V for 0.3 seconds

Failsafe

Setting mode : REC Fix at REC position

Setting mode : Except REC Fix at FRE position

SPECIFICATION

※ Voltage value of Intake potentiometer as a function of position of Intake door

Door position	Voltage
FRE	0.3±0.15V
REC	4.65±0.15V

DIAGNOSTIC CIRCUIT DIAGRAM

MONITOR SCANTOOL DATA

■ Check Actuation Test

1.	Connect scantool with diagnostic connector.

2.	Warm up the engine to normal temperature after engine start.

3.	Select ” Intake Potentiometer ” parameter on the current data with scantool.

4.	Perform Actuation Test for Air Inlet Mode Selection – Reculation /Fresh in order.

With performing Actuation test, check that the value of each position sensors are changing.

Recirculation : About 90%, Fresh : About 10%.

Are the value of each position sensors changed when performing actuation test ?

	▶ This is a intermittent problem caused by poor contact of component or Control Unit. ▶ Thoroughly check the looseness, poor connection, bent, corrosion, contamination, deformation or damage of connector. ▶ Repair or replace as necessary
	▶ Go to ” Inspection/Repair ” procedure.

TERMINAL AND CONNECTOR INSPECTION

1.	Many malfunctions in the electrical system are caused by poor connection. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

2.	Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

Has a problem been found?

	▶ Repair as necessary .
	▶ Go to “W/Harness Inspection” procedure.

SIGNAL CIRCUIT INSPECTION

■ Check for open in harness

1.	Ignition “OFF”

2.	Disconnect Intake actuator and A/C control unit main harness connector.

Measure resistance between Signal(F/B) terminal of Intake actuator harness connector and Signal(F/B) terminal of A/C-ECU harness connector.

below 1Ω

Is the measured resistance within specification?

	▶ Go to “Check short to ground in harness” as follows.
	▶ Check for open in harness. ▶ Repair as necessary .

■ Check short to ground in harness

1.	Ignition “OFF”

2.	Disconnect Intake actuator and A/C control unit main harness connector.

Measure resistance between Signal(F/B) terminal of Intake actuator harness connector and chassis ground.

Infinity

Is the measured resistance within specification?

	▶ Go to “Power circuit Inspection” procedure.
	▶ Check for short to ground in control harness. ▶ Repair as necessary .

POWER CIRCUIT INSPECTION

■ Check power in harness

1.	Ignition “OFF”

2.	Disconnect Intake actuator and Connect A/C control unit main harness connector.

3.	Ignition “ON”

Measure voltage between Sensor REF(5V) terminal of Intake actuator harness connector and chassis ground.

approx. 5V

Is the measured voltage within specification?

	▶ Go to ” Component inspection” procedure.
	▶ Check for open and short to ground in harness. ▶ Repair as necessary

COMPONENT INSPECTION

■ Check Intake actuator

1.	Ignition “OFF”

2.	Disconnect Intake actuator and connect A/C control unit main harness connector.

3.	Connect (+) terminal of battery to FRE(+) of intake actuator and (-) terminal to REC(-). (Component side)

4.	Verify that the actuator operates to the FRE position.

Verify that the Intake actuator operates to the REC position with reverse connecting. (REC(+) and FRE(-)) (Component side)

Refer the specifications in Fig.1)

Fig.1)

Actuator harness	FRE(+)	REC(-)	Door position
Battery terminal	12 V	ground	FRE
Battery terminal	ground	12 V	REC

Fig.1) ※ Function of the actuator motor according to terminal connection type. (observe safety regulations)

Is “Door position” display near the specified value?

	▶ Go to “Check potentiometer” procedure.
	▶ Substitute with a known-good Intake actuator and check for proper operation. If the problem is corrected, replace Intake actuator

■ Check potentiometer

1.	Ignition “OFF”

2.	Disconnect Intake actuator and A/C control unit main harness connector.

3.	Ignition “ON”(ENGINE “OFF”).

Measure voltage between Signal(F/B) terminal of Intake actuator harness connector and chassis ground. (Component side)

Refer the specifications in Fig.2)

Fig.2)

Door position	Voltage
FRE	0.3±0.15V
REC	4.65±0.15V

Fig.2) ※ Voltage value of intake potentiometer as a function of intake door position.

Is “voltage” display near the specified value?

	▶ Check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary
	▶ Substitute with a known-good Intake actuator and check for proper operation. If the problem is corrected, replace Intake actuator

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