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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Blazer - 4WD - RHD 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 DTC B0161 Outside Air Temp Sensor Circuit High

Object Number: 569104 Size: MF
HVAC Components
ECC Module and Temperature Sensors
Handling ESD Sensitive Parts Notice
DTC B0165, B0166, B0180, B0181, B0185, B0186 Thumbnail
DTC B0165, B0166, B0180, B0181, B0185, B0186 Thumbnail
DTC B0165, B0166, B0180, B0181, B0185, B0186 Thumbnail

Circuit Description

The outside (ambient) air temperature sensor is a thermistor used to control the signal voltage in the electronic climate control module. The electronic climate control module supplies a reference voltage (about 5 volts) on CKT 636 (DK GRN/WHT) to the sensor. When the outside (ambient) air temperature is cold, the thermistor resistance is high. Therefore, the electronic climate control module will receive a high voltage input. If the outside air temperature is hot, the thermistor resistance is low . Therefore, the electronic climate control module will receive a low signal voltage input. Refer to Sensor Resistance Table .

Conditions for Setting the DTC

With the ignition switch is in the ON position, the electronic climate control module will detect DTC B0161 any time CKT 636 (DK GRN/WHT) is near 5 volts or higher.

Action Taken When the DTC Sets

The electronic climate control module will use a default value of -3.3°C (26°F) (or 168 A/D counts) until the fault is cleared.

Conditions for Clearing the MIL/DTC

This fault will clear as soon as the fault goes away or has been repaired. The system will then return to normal operation. History DTCs can only be cleared by removing and restoring B+ or by using the scan tool.

Diagnostic Aids
    • The electronic climate control module may set class 2 lost communication DTCs when the body control module (BCM) or the vehicle control module (VCM) is being reprogrammed. After reprogramming, check for DTCs in the electronic climate control module. Clear any history U DTCs, then resume diagnosis.
    • Visually inspect the sensor connector and harness for corrosion and damage. The resistance value of the sensor must be within 300-170,000 ohms. Refer to Sensor Resistance Table . If resistance is not within specifications, replace the sensor.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step measures the resistance of the outside (ambient) air temperature sensor.

    2.

  2. This step inspects for B+ on CKT 636.

    3.

  3. This step determines if the short to B+ is in CKT 636 or in the electronic climate control module.

    4.

  4. This step inspects for an open in CKT 552.

    5.

  5. This step replaces a defective outside (ambient) air temperature sensor.

    6.

  6. This step repairs an open in CKT 552.

    7.

  7. This step inspects for intermittents and tests for a malfunctioning electronic climate control module.

    8.

  8. This step replaces a defective electronic climate control module.

    9.

  9. This step inspects for 5 volts on CKT 636.

    10.

  10. This step determines if the open is in CKT 636 or in the electronic climate control module.

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check

2

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the outside (ambient) air temperature sensor.
  3. Measure the resistance between sensor terminal A and terminal B.
  4. Compare the reading to the temperature/resistance table. Refer to Sensor Resistance Table .

Is the resistance within the range specified in the table?

--

Go to Step 3

Go to Step 7

3

  1. Turn the ignition switch to the ON position.
  2. Measure the voltage at terminal B of the outside (ambient) air temperature sensor harness connector and ground.

Is the battery voltage within the specified range?

9-6 V

Go to Step 3

Go to Step 12

4

Inspect for a short to B+ in CKT 636 (DK GRN/WHT).

Did you find a short to B+?

--

Go to Step 5

Go to Step 11

5

Repair the short to B+ in CKT 636 (DK GRN/WHT).

Is the repair complete?

--

Go to Diagnostic System Check

--

6

Inspect for continuity to ground at terminal A of the outside (ambient) air temperature sensor harness connector and ground.

Is continuity present?

--

Go to Step 10

Go to Step 8

7

Replace the outside air temperature sensor.

Is the replacement complete?

--

Go to Diagnostic System Check

--

8

Inspect for an open in CKT 552 (BLK).

Did you find an open?

--

Go to Step 9

Go to Step 11

9

Repair the open in CKT 552 (BLK).

Is the repair complete?

--

Go to Diagnostic System Check

--

10

  1. Turn the ignition switch to the OFF position.
  2. Reconnect the outside (ambient) air temperature sensor.
  3. Reconnect the electronic climate control module.
  4. Turn the ignition switch to the ON position.
  5. Clear any electronic climate control module DTCs.

Does the DTC reset?

--

Go to Step 11

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

11

Replace the electronic climate control module.

Is the replacement complete?

--

Go to Diagnostic System Check

--

12

Measure the voltage on terminal B of the outside (ambient) air temperature sensor connector to ground.

Is the voltage within the specified range?

4-6 V

Go to Step 6

Go to Step 13

13

Inspect for an open in CKT 636 (DK GRN/WHT).

Did you find an open?

--

Go to Step 14

Go to Step 11

14

Repair the open in CKT 636 (DK GRN/WHT).

Is the repair complete?

--

Go to Diagnostic System Check

--