Circuit Description
The transmission control module (TCM) is an electronic device which monitors inputs to control various transmission functions including shift quality and transmission sensors, switches, and components to process for use within its control program. Based on this input information, the TCM controls various transmission output functions and devices.
DTCs P0725, P0726, and P0727 are related to the same circuit. These DTCs will not illuminate the malfunction indicator lamp (MIL), however, the DTC will be stored in memory.
The following information is transmitted between the TCM and the engine control module (ECM) through the controller area network (CAN) line:
| • | Engine malfunction signal |
| • | Engine speed |
| • | Engine output torque reduction signal |
| • | Engine coolant temperature (ECT) |
Conditions for Setting the DTC
| • | The turbine speed is more than 1,500 RPM. |
| • | The engine speed is less than 400 RPM. |
| • | The system voltage is too high or too low. |
| • | The CAN transmitting wiring harness is shorted or open. |
| • | The TCM or ECM is defective. |
Action Taken When the DTC Sets
| • | The hold lamp will blink. |
| • | The 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 4th 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. |
| • | Clear the DTCs with a scan tool. |
Diagnostic Aids
| • | An intermittent condition may be caused by a poor connection, rubbed-through wiring insulation, or a wire that is broken inside the insulation. |
| • | Any circuitry that is suspected as causing the complaint should be thoroughly inspected for the following conditions: |
| - | Backed-out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed |
| - | Damaged terminals |
| - | Poor terminal-to-wire connection |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Automatic Transmission? | -- | Go to Step 2 | |
2 |
Is the speed within the specified range? | 0-7,000 RPM | Go to Diagnostic Aids | Go to Step 3 |
3 |
Is the resistance within the specified values? | 0 ohms | Go to Step 5 | Go to Step 4 |
4 | Repair the malfunctioning terminals as necessary. Is the action complete? | -- | System OK | -- |
5 |
Is the resistance within the specified range? | 11-14 V | Go to Step 6 | Go to Step 7 |
6 | Repair the short to power. Is the action complete? | -- | System OK | -- |
7 | Inspect the engine speed. Go to Diagnostic System Check - Engine Controls in Engine Controls-2.0L or Diagnostic System Check - Engine Controls in Engine Controls-2.5L. Was a condition found? | -- | -- | Go to Step 8 |
8 |
Is DTC P0727 set? | -- | Go to Step 9 | Go to Step 10 |
9 | Replace the ECM. Refer to Engine Control Module Replacement in Engine Controls-2.0L or Engine Control Module Replacement in Engine Controls-2.5L. Is the action complete? | -- | Go to Step 10 | -- |
10 |
Did the last test fail or is the current DTC displayed? | -- | Go to Step 2 | System OK |
