Circuit Description
The 1-2 shift solenoid (SS) valve controls transmission fluid pressure acting on the 1-2 and 2-3 shift valves to position the valves for the appropriate gear. The 1-2 SS valve is a normally open exhaust valve located on the control valve body. The transmission control module (TCM) provides voltage to the pressure control solenoid, the shift solenoids, and the torque converter clutch pulse width modulated (TCC PWM) solenoid through 2 separate solid-state devices called high side drivers (HSD) - HSD1 and HSD2. HSD1 provides electrical power to the pressure control solenoid. HSD2 provides electrical power to the shift solenoids, and the TCC PWM solenoid. The TCM then commands the solenoid ON or OFF by also providing a ground path. When the 1-2 SS valve is commanded ON, the TCM senses low voltage. When the 1-2 SS valve is commanded OFF, the TCM senses high voltage.
If the TCM detects a continuous open or short to ground in the 1-2 SS valve circuit, DTC P0973 sets. DTC P0973 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0973 1-2 Shift Solenoid (SS) Control Circuit Low Voltage
Conditions for Running the DTC
| • | The engine is running for 5 seconds and not in fuel cut-off. |
| • | The HSD1 is commanded ON. |
Conditions for Setting the DTC
The 1-2 SS valve feedback circuit indicates a continuous open or short to ground for 4.4 seconds.
Action Taken When the DTC Sets
| • | The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. |
| • | The TCM commands maximum line pressure. |
| • | The TCM inhibits 3-2 downshifts above 51 km/h (31 mph). |
| • | The TCM freezes transmission adaptive functions. |
| • | The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records. |
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records. |
| • | The TCM stores DTC P0973 in TCM history. |
Conditions for Clearing the MIL/DTC
| • | The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request. |
| • | A scan tool can clear the MIL/DTC. |
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring. |
| • | The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the electrical operation of the solenoid.
-
This step tests the TCM and the wiring to the transmission.
-
This step verifies that the circuit has the correct resistance.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||
2 |
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from both the ECM and the TCM. Is DTC P0976 or P2761 also set? | -- | Go to Step 3 | Go to Step 5 | ||||
3 | Test the ignition 1 voltage circuit of the 1-2 SS valve for an open or a short to ground between the TCM C1 connector and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 4 | ||||
4 |
Important: The condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics for complete circuit distribution. Test the ignition 1 voltage circuit of the 1-2 SS valve for an open or a short to ground between the AT inline 20-way connector and the 1-2 SS valve. Refer to Circuit Testing . Did you find the condition? | -- | Go to Step 16 | -- | ||||
Does the solenoid click when commanded ON and OFF? | -- | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 6 | |||||
Is the test lamp ON when you command the solenoid ON, and OFF when you command the solenoid OFF? | -- | Go to Step 10 | Go to Step 7 | |||||
7 | Is the test lamp always ON? | -- | Go to Step 8 | Go to Step 9 | ||||
8 | Test the control circuit of the 1-2 SS valve for a short to ground between the TCM connector C2 and the AT inline 20-way connector. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 18 | ||||
9 | Test the control circuit of the 1-2 SS valve for an open between the TCM connector C2 and the AT inline 20-way connector. Refer to Testing for Continuity and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 18 | ||||
Is the resistance within the specified range? | 19-31 ohms | Go to Step 13 | Go to Step 11 | |||||
11 | Is the resistance greater than the specified value? | 31 ohms | Go to Step 12 | Go to Step 13 | ||||
12 |
Refer to Testing for Continuity . Did you find a condition? | -- | Go to Step 16 | Go to Step 17 | ||||
13 | Measure the resistance from the 1-2 SS valve control circuits of the J 44152 to ground. Refer to Automatic Transmission Inline 20-Way Connector End View . Is the resistance less than the specified value? | 100 ohms | Go to Step 14 | Go to Step 15 | ||||
14 | Test the control circuit of the 1-2 SS valve for a short to ground between the AT inline 20-way connector and the 1-2 SS valve. Refer to Testing for Short to Ground . Did you find the condition? | -- | Go to Step 16 | -- | ||||
15 | Measure the resistance between the 1-2 SS valve control circuits and all other terminals, except the 2-3 SS valve control circuit, the TCC PWM solenoid valve control circuit, and the ignition 1 voltage circuit of the J 44152 . Refer to Automatic Transmission Inline 20-Way Connector End View . Is the resistance less than the specified value? | 100 ohms | Go to Step 16 | Go to Step 17 | ||||
16 | Replace the automatic transmission wiring harness. Refer to Wiring Harness Replacement . Did you complete the replacement? | -- | Go to Step 19 | -- | ||||
17 | Replace the 1-2 SS valve. Refer to Control Valve Body Disassemble . Did you complete the replacement? | -- | Go to Step 19 | -- | ||||
18 | Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 19 | -- | ||||
19 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 20 | Go to Step 2 | ||||
20 | With the scan tool, observe the stored information, capture info. and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |
