Circuit Description
The 2nd brake control solenoid is energized and de-energized by the Powertrain Control Module (PCM). The solenoid controls the orifice control valve which engages and disengages the O/D and 2nd brake. The 2nd brake control solenoid is activated when the reverse clutch is applied or released. The combined action of the solenoid is to control shift timing and shift feel.
Conditions for Setting the DTC
| • | Solenoid resistance is 30 ohms or lower (short circuit) when the solenoid is energized. |
| • | Solenoid resistance is 100K ohms or higher (open circuit) when the solenoid is not energized. |
| • | One driving cycle detection logic. |
Action Taken When the DTC Sets
A DTC P1790 is stored, but the Malfunction Indicator Lamp (MIL) does not illuminate.
Diagnostic Aids
Inspect for the following conditions:
| • | Faulty electrical circuit/open or short to the ground between the solenoid and the PCM |
| • | A faulty PCM |
| • | A faulty Solenoid |
An intermittent may be caused by the following conditions:
| • | A poor connection |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
Inspect the Powertrain Control Module (PCM) harness connectors for the following conditions:
| • | Backed out terminal |
| • | Improper mating |
| • | Broken locks |
| • | Improperly formed or damaged terminals |
| • | Inadequate terminal-to-wire connections |
Perform the following steps if DTC P1790 cannot be duplicated:
- Read the information in the freeze frame data.
- Use the data to determine the vehicle operating conditions when the DTC was set.
If any wiring repairs need to be made, refer to Repair Procedures in Electrical Diagnosis.
DTC Confirmation Procedure
- Turn the ignition switch to LOCK.
- Connect the Scan Tool to Data Link Connector (DLC).
- Turn the ignition switch to ON.
- Use a Scan Tool to clear the following items from the PCM memory:
- Start the engine.
- Step firmly on the brake pedal.
- Shift the manual selector to Drive (D).
- Leave the selector in Drive (D) for 10 seconds.
- Accelerate the vehicle in Drive (D).
- Keep driving for 60 seconds at 50 km/h (30 mph).
- Stop the vehicle.
- Use a Scan Tool to inspect DTC P1790.
| • | The DTC |
| • | The pending DTC |
| • | The freeze frame data |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
-
This step inspects the condition of the solenoid and the internal electrical harness for damage.
-
This step inspects for an open or short in the 2ND brake control circuit.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics | ||||
Was the On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls | |
2 |
Does the scan tool display any other DTCs in addition to DTC P1790? | -- | Go to applicable DTC table | Go to Step 3 |
Is the resistance within the specified value? | 11-15 ohms at 20°C (68°F) | Go to Step 4 | Go to Step 5 | |
Is the resistance within the specified value? | 11-15 ohms at 20°C (68°F) | Go to Step 6 | Go to Step 7 | |
5 |
Is the action complete? | -- | Go to Step 8 | -- |
6 | Replace the PCM. Is the repair complete? | -- | Go to Step 8 | -- |
7 | Repair the short, open or high resistance in the 2ND brake control solenoid circuit. Is the action complete? | -- | Go to Step 8 | -- |
8 |
Are any DTCs displayed on the Scan Tool? | -- | Go to the applicable DTC table | System OK |
