GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1999 🢒 Aurora 🢒 DTC 🢒 DTC P1533 Air Conditioning (A/C) Low Side Temperature Sensor Circuit

Object Number: 191644 Size: SF
Engine Controls Components
Cell 21: A/C Sensors
OBD II Symbol Description Notice
ESD Notice

Circuit Description

The A/C low side temperature sensor uses a thermister to control the signal voltage to the PCM. The PCM applies 5 volts on CKT 731 to the sensor. When the sensor is cold, its resistance is high; therefore, the PCM will see a high signal voltage. As the sensor warms, its resistance becomes less and the signal voltage is pulled low through the ground, CKT 470. This diagnostic detects a shorted to ground or open A/C low side temperature sensor circuit by setting the DTC if the PCM monitors a signal voltage, temperature, that is too high or low.

Conditions for Running the DTC
    •  Ambient Air Temperature between 4°C (39°F) and 99°C (210°F).
    •  Ambient Air Temperature sensor failure not indicated by the HVAC controller.

Conditions for Setting the DTC

A/C low side temperature sensor reads less than -37°C (-35°F) or more than 99°C (210°F).

Action Taken When the DTC Sets

Disable the A/C compressor clutch.

    •  The Malfunction Indicator Lamp (MIL) will not illuminate.
    •  No message will be displayed.

Conditions for Clearing the DTC
    •  A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test.
    •  A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
    • Use a scan tool to clear DTCs.
    • Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in Powertrain Control Module Description .

Diagnostic Aids

With the vehicle engine not running and at ambient temperature the A/C temperature sensor should also be near ambient temperature. If the A/C temperature sensor is not near ambient temperature check for a sensor or circuit with resistance that is too high or too low. A sensor temperature reading that is too high would indicate a shorted or low resistance sensor or circuit. A sensor temperature reading that is too low would indicate an open or high resistance sensor or circuit.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2
  1. Ignition ON engine OFF.
  2. Using a scan tool observe the A/C Low Side Tmp. display.

Does the scan tool display a value between the range specified?

-37°C (-35°F) - 99°C (210°F)

Fault not present. Refer to Diagnostic Aids

Go to Step 3

3

Is the temperature displayed less than the value specified?

-37°C (-35°F)

Go to Step 4

Go to Step 7

4
  1. Turn the key to OFF.
  2. Disconnect the sensor connector.
  3. Jumper connector terminals A and B (harness side) together.
  4. Turn the key ON.

Is the temperature displayed more than the value specified?

99°C (210°F)

Go to Step 12

Go to Step 5

5
  1. Remove the jumper.
  2. Jumper terminal A to ground.

Is the temperature displayed more than the value specified?

99°C (210°F)

Go to Step 9

Go to Step 6

6
  1. Remove the jumper to ground.
  2. Store fluid life, turn the key to OFF and wait 30 seconds.
  3. Disconnect PCM connector C1.
  4. Using DMM J 39200 measure the resistance between PCM connector C1 terminal 52 and sensor connector terminal A.

Is the resistance more than the value specified?

5 ohms

Go to Step 10

Go to Step 14

7

Disconnect the sensor connector.

Is the temperature displayed less than the value specified?

-37°C (-35°F)

Go to Step 12

Go to Step 8

8
  1. Record the fluid life indexes, turn the key to OFF and wait 30 seconds.
  2. Disconnect PCM connector C1.
  3. Using DMM J 39200 measure the resistance to ground at PCM connector C1 terminal 52.

Is the resistance more than the value specified?

10K ohms

Go to Step 14

Go to Step 11

9

Repair the open in the A/C Low Temperature Sensor ground circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

10

Repair the open in the A/C Low Temperature Sensor signal circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

11

Repair the short to ground in the A/C Low Temperature Sensor signal circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

12
  1. Check terminal contact at the sensor connector.
  2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 13

13

Replace the sensor. Refer to Heating and Air Conditioning.

Is the replacement complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

14
  1. Check terminal contact at the PCM connector C1 terminals 52 and 73.
  2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 15

15

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the replacement complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--