Circuit Description
The 1-2 shift solenoid (SS) valve controls the fluid flow acting on the 1-2 and 3-4 shift valves. The solenoid is a normally-open exhaust valve. With the 2-3 SS valve, the 1-2 SS valve allows 4 different shifting combinations. The solenoid attaches to the control valve body within the transmission. The 1-2 SS valve receives ignition voltage through the ignition voltage circuit. The transmission control module (TCM) controls the solenoid by providing the ground path on the 1-2 SS valve control circuit.
When the TCM detects a continuous open, short to ground in the 1-2 SS valve circuit, then 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 system voltage is 8-18 volts. |
| • | The engine run time is greater than 5 seconds. |
Conditions for Setting the DTC
The TCM detects an open or short to ground in the 1-2 SS valve circuit 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 drive trip in which the Conditions for Setting the DTC are met. |
| • | The TCC commands maximum line pressure. |
| • | The TCM inhibits 3-2 downshift until vehicle speed is 40 km/h (25 mph) or less. |
| • | 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 during the second consecutive trip in which the Conditions for Setting the DTC are met. |
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 default actions when the ignition 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.
Step | Action | Value | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear Info function will erase the stored Freeze Frame and Failure Records from the TCM. Are DTCs P0976 or P2764 also set? | -- | Go to Step 3 | Go to Step 9 | |||||||
3 |
Was the fuse open? | -- | Go to Step 4 | Go to Step 7 | ||||||
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 a short to ground between the fuse block and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 5 | ||||||
5 |
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. Did you find the condition? | -- | Go to Step 17 | Go to Step 6 | ||||||
6 |
Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||
7 | Test the ignition 1 voltage circuit of the 1-2 SS valve for an open between the fuse block 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 20 | Go to Step 8 | ||||||
8 | Test the ignition 1 voltage circuit of the 1-2 SS valve for an open between the AT inline 20-way connector and the solenoid. Refer to Testing for Continuity . Did you find the condition? | -- | Go to Step 17 | Go to Testing for Intermittent Conditions and Poor Connections | ||||||
9 |
Refer to Automatic Transmission Inline 20-Way Connector End View . Does the test lamp turn ON and OFF? | -- | Go to Step 12 | Go to Step 10 | ||||||
10 | Test the ignition 1 voltage circuit of the 1-2 SS valve for an open between the fuse block 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 20 | Go to Step 11 | ||||||
11 | Test the control circuit of the 1-2 SS valve for an open or short to ground between the TCM and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 19 | ||||||
12 |
Refer to Automatic Transmission Inline 20-Way Connector End View . Does the resistance measure within the specified range? | 19-31 ohms | Go to Step 13 | Go to Step 16 | ||||||
13 | Measure the resistance from both terminals of the 1-2 SS valve to the transmission case. Are both readings greater than the specified value? | 250 K ohms | Go to Step 14 | Go to Step 15 | ||||||
14 | Measure the resistance on the control side of the 1-2 SS valve and all other terminals of the AT inline 20-way connector. Refer to Testing for Continuity . Is the resistance less than the specified value? | 250 K ohms | Go to Step 16 | Go to Testing for Intermittent Conditions and Poor Connections | ||||||
15 |
Are both readings greater than the specified value? | 250 K ohms | Go to Step 17 | Go to Step 18 | ||||||
16 |
Is the resistance within the specified range? | 19-31 ohms | Go to Step 17 | Go to Step 18 | ||||||
17 | Replace the AT wiring harness assembly. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||
18 | Replace the 1-2 SS valve. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||
19 | Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||
20 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 21 | Go to Step 2 | ||||||
21 | 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 |
