Circuit Description
The shift solenoids are two identical, normally open electronic exhaust valves that control upshifts and downshifts in all forward gear ranges. These shift solenoids work together in a combination of ON and OFF sequences to control the line pressure and shift mechanisms, such as clutches and brakes.
Solenoid 1 controls the high or low of the line pressure - the flow to each clutch valve - by the operation type ON/OFF. For example, solenoid 1 is ON, line pressure will be low (599-799 kPa) (87-116 psi) (6-8 bar); solenoid 1 is OFF, line pressure will be high (1599-1799 kPa) (232-261 psi) (16-18 bar). Solenoid 2 controls the oil flow to clutch valve E or lock-up clutch valve by the ON/OFF signal.
The transmission control module (TCM) monitors numerous inputs to determine the appropriate solenoid state combination and transaxle gear tor the vehicle operating conditions.
Conditions for Setting the DTC
| • | Solenoid wiring shorted to ground. |
| • | No DTC P1850, P1852. |
| • | Immediately after the above condition occurs. |
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. |
Conditions for Clearing the Hold Lamp/DTC
| • | The hold lamp will turn OFF when the malfunction has not occurred after three-ignition cycle. |
| • | 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 P1851 sets, the possible cause of the fault could be solenoid 1.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Perform the Diagnostic System Check. Is the check complete? | -- | Go to Step 2 | |
2 |
Does solenoid 1 change ON/OFF? | -- | Go to Diagnostic Aids | Go to Step 3 |
3 |
Is the voltage within the specified value? | 11-14 V | Go to Step 4 | Go to Step 5 |
4 | Repair the internal line solenoid 1 for a short to power. Is the repair complete? | -- | System OK | -- |
5 | Replace solenoid 1. Is the replacement complete? | -- | Go to Step 6 | -- |
6 | Inspect if any DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | System OK |
