DTC P0781 Non Europe or N American Emissions
Circuit Description
The special feature of a 4HP 16 automatic transaxle is that it operates without freewheels. Shifting between individual gears takes place by means of overlapping clutch engagement and release.
The advantages of overlap shifting are as follows:
| • | The transaxle can be a more compact design and is lighter on account of the absence of freewheels and the lower number of shift elements. |
| • | Lower drag losses, i.e., higher efficiency |
| • | Lower peak torque acting on the components and driveline |
However, overlap shifting necessitates high-performance hardware and software, and precision engine signals.
Conditions for Setting the DTC
| • | The transmission oil temperature is greater than -10°C (+14°F). |
| • | The selector lever is not in the neutral (N) or park (P) position. |
| • | System voltage is greater than 9 volts. |
| • | No input speed error DTCs P0715, P0716, and P0717 are set. |
| • | The output speed is greater than 256 RPM. |
| • | The input speed is greater than 400 RPM. |
| • | The 1-2 gear shift is active. |
Action Taken When the DTC Sets
| • | The hold lamp will blink. |
| • | The transmission control module (TCM) will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer. |
| • | Adopt Emergency/Substitute mode and constant 1st gear. |
| • | Open lock up clutch |
Conditions for Clearing the Hold Lamp/DTC
| • | The hold lamp will turn OFF when the malfunction has not occurred after 3 ignition cycles. |
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | Using a scan tool can clear history DTCs. |
Diagnostic Aids
When DTC P0781 sets, the possible cause of fault could be the transmission control module (TCM).
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Automatic Transmission? | -- | Go to Step 2 | |
2 |
Was the condition found and corrected? | -- | Verify Repair | Go to Step 3 |
3 | Inspect the electronic control module (ECM). Was a condition found? | -- | Go to Engine Control Module Replacement in Engine Controls-2.0L | Go to Step 4 |
4 |
Is the voltage within the specified values? | 11-14 V | Go to Step 5 | |
5 | Replace the TCM. Refer to Transmission Control Module Replacement . Did you complete the replacement? | -- | Go to Step 6 | -- |
6 |
Has the last test failed or is the current DTC displayed? | -- | Go to Step 7 | System OK |
7 | Repair or Replace the transaxle assembly as necessary. Refer to Transmission Replacement , if necessary. Did you complete the repair? | -- | Go to Step 8 | -- |
8 |
Are there any DTCs that have not been diagnosed? | -- | Go to Step 2 | System OK |
DTC P0781 European and N America Emissions
Circuit Description
The special feature of a 4HP 16 automatic transaxle is that it operates without freewheels. Shifting between individual gears takes place by means of overlapping clutch engagement and release.
The advantages of overlap shifting are as follows:
| • | The transaxle can be a more compact design and is lighter on account of the absence of freewheels and the lower number of shift elements. |
| • | Lower drag losses, i.e., higher efficiency |
| • | Lower peak torque acting on the components and driveline |
However, overlap shifting necessitates high-performance hardware and software, and precision engine signals.
Conditions for Setting the DTC
| • | The transmission oil temperature is greater than -10°C (+14°F). |
| • | The selector lever is not in the neutral (N) or park (P) position. |
| • | System voltage is greater than 9 volts. |
| • | No input speed error DTCs P0715, P0716, and P0717 are set. |
| • | The output speed is greater than 256 RPM. |
| • | The input speed is greater than 400 RPM. |
| • | The 1-2 gear shift is active. |
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) lamp will illuminate. |
| • | The transmission control module (TCM) will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer. |
| • | Adopt Emergency/Substitute mode and constant 1st gear. |
| • | Open lock up clutch |
Conditions for Clearing the MIL/DTC
| • | The MIL lamp will turn OFF when the malfunction has not occurred after 3 ignition cycles. |
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | Using a scan tool can clear history DTCs. |
Diagnostic Aids
When DTC P0781 sets, the possible cause of fault could be the transmission control module (TCM).
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Automatic Transmission? | -- | Go to Step 2 | |
2 |
Was the condition found and corrected? | -- | System OK | Go to Step 3 |
3 | Inspect the electronic control module (ECM). Was a condition found? | -- | Go to Engine Control Module Replacement in Engine Controls-2.0L or Engine Control Module Replacement in Engine Controls-2.5L | Go to Step 4 |
4 |
Is the voltage within the specified values? | 11-14 V | Go to Step 5 | |
5 | Repair or Replace the transaxle assembly as necessary. Refer to Transmission Replacement , if necessary. Did you complete the repair? | -- | Go to Step 6 | -- |
6 |
Has the last test failed or is the current DTC displayed? | -- | Go to Step 7 | System OK |
7 | Replace the transaxle assembly. Refer to Transmission Replacement . Did you complete the replacement? | -- | Go to Step 8 | -- |
8 |
Are there any DTCs that have not been diagnosed? | -- | Go to Step 2 | System OK |
