Circuit Description
The shift solenoids are 2 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, if solenoid 1 is ON, the line pressure will be low, 599-799 kPa (87-116 psi). If solenoid 1 is OFF, the line pressure will be high, 1 599-1 799 kPa (232-261 psi). Solenoid 2 controls the oil flow to the clutch valve E or the 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 for the vehicle operating conditions.
Conditions for Setting the DTC
| • | The solenoid 1 wiring is shorted to ground. |
| • | No DTCs P1850 or P1852 are set. |
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 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 P1851 sets, the possible cause of the fault could be solenoid 1.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Does the solenoid 1 change ON/OFF? | -- | Go to Diagnostic Aids | Go to Step 3 |
3 |
Is the resistance within the specified values? | 11-14 V | Go to Step 4 | Go to Step 5 |
4 | Repair the internal line, solenoid 1, for a short to power. Did you complete the repair? | -- | System OK | -- |
5 | Replace the solenoid 1. Did you complete the replacement? | -- | Go to Step 6 | -- |
6 | Check if any DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | System OK |
