GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Epica 🢒 DTC 🢒 DTC P0218

Circuit Description

The transmission fluid temperature (TFT) sensor is a positive temperature coefficient thermistor, temperature sensitive resistor, that provides information to the transmission control module (TCM) regarding transaxle fluid temperature. The temperature sensor is located in the valve body. The calculated temperature is a factor used to determine the shift time and shift delay time.

The internal electrical resistance of the sensor varies in relation to the operating temperature of the transaxle fluid.

The TCM sends a 5-volt reference signal to the temperature sensor and measures the voltage rise in the electrical circuit. A higher fluid temperature creates a higher resistance in the temperature sensor, thereby measuring a higher voltage signal.

The TCM measures this voltage as another input to help control line pressure, shift schedules, and torque converter clutch (TCC) apply. When transaxle fluid temperature reaches 120°C (248°F), the TCM enters HOT MODE. Above this temperature the TCM modifies the transaxle shift schedule and the TCC apply in an attempt to reduce fluid temperature by reducing transaxle heat generation.

Conditions for Setting the DTC
    • The calculated temperature is compared with the predetermined minimum and maximum value.
    • If the temperature is less than the minimum value or greater than the maximum value, the current temperature is regarded as range and the corresponding error will be set.

Action Taken When the DTC Sets
    • No lamp control required by diagnostic information should be stored immediately when the malfunction is detected.
    • The TCM assumes the transaxle fluid temperature is 60°C (140°F).
    • No influence on driveability

Conditions for Clearing the DTC

Using a scan tool can clear history DTCs.

Diagnostic Aids

When DTC P0218 sets, the possible cause of the fault could be the transaxle temperature sensor.

Step

Action

Values

Yes

No

1

Did you perform the Diagnostic System Check-Automatic Transmission?

--

Go to Step 2

Go to Diagnostic System Check - Automatic Transmission

2
  1. Install the scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Record and clear the DTCs.
  4. Turn OFF the ignition.
  5. Turn ON the ignition, with the engine OFF.
  6. Select transaxle fluid temperature (TFT) on the scan tool.
  7. Drive the vehicle and observe the scan tool for either of the following conditions:
    8. • The TFT does not change more than 1.5°C (2.7°F) in 80 seconds since start-up.
    • The TFT changes more than 20°C (36°F) within 7 seconds. This is an unrealistic change.

Did either of the fail conditions occur?

--

Go to Step 3

Go to Diagnostic Aids

3
  1. Turn OFF the ignition.
  2. Disconnect the transaxle wiring connector.
  3. Measure the resistance between terminals 9 and 4 of the transaxle wiring connector.

Is the resistance within the specified values?

TFT 25°C (77°F)

990 ohms

Go to Step 7

Go to Step 4

4
  1. Remove the oil pan.
  2. Disconnect the wiring connector of the transaxle fluid temperature sensor.
  3. Inspect the automatic transaxle wiring harness for an intermittent short or open.

Was a problem found?

--

Go to Step 5

Go to Step 6

5

Replace the automatic transaxle wiring harness.

Is the replacement complete?

--

System OK

--

6

Replace the TFT sensor.

Is the replacement complete?

--

System OK

--

7
  1. Disconnect the automatic transaxle wiring connector and disconnect the wiring connector of the transmission control module (TCM).
  2. Measure the resistance between terminal 4 of the transaxle wiring connector and terminal B1 of the TCM wiring connector.
  3. Measure the resistance between terminal 9 of the transaxle wiring connector and terminal A4 of the TCM wiring connector.

Is the resistance within the specified value?

∞

Go to Step 9

Go to Step 8

8
  1. Inspect the automatic transaxle wiring for an intermittent short to ground or open condition.
  2. Inspect the automatic TFT sensor wiring harness for an intermittent short to ground or open condition.
  3. Repair the circuit if necessary.

Is the repair complete?

--

System OK

--

9
  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage of terminal A4 of the TCM wiring connector.
  3. Measure the voltage of terminal B1 of the TCM wiring connector.

Is the voltage within the specified range?

9-16 V

Go to Step 10

Go to Step 11

10
  1. Inspect the automatic transaxle wiring harness for an intermittent short to power.
  2. Inspect the automatic TFT sensor wiring harness for an intermittent short to power.
  3. Repair the circuit if necessary.

Is the repair complete?

--

System OK

--

11

Replace the TCM. Refer to Transmission Control Module Replacement .

Is the replacement complete?

--

Go to Step 12

--

12
  1. After the repair use the scan tool Clear Info. function and road test the vehicle.
  2. Review the DTC Info.

Has the last test failed or is the current DTC displayed?

--

Go to Step 2

System OK