Circuit Description
The 1-2 shift solenoid (1-2 SS) valve controls transmission fluid pressure acting on the 1-2 and 3-4 shift valves to position the valves for the appropriate gear. The 1-2 SS valve is a normally open exhaust valve located on the lower control valve body. Ignition voltage is supplied to the solenoid on circuit 839. The output driver module (ODM), within the PCM, commands the solenoid ON or OFF by providing a ground path through circuit 1222. When the 1-2 SS valve is commanded ON, the PCM senses low voltage. When the 1-2 SS valve is commanded OFF, the PCM senses high voltage.
If the PCM detects voltage limits that do not meet the calibration, then DTC P0753 sets. DTC P0753 is a Type A DTC.
Conditions for Running the DTC
| • | No ODM DTC P1650. |
| • | The engine run time is greater than 5 seconds. |
Conditions for Setting the DTC
The PCM detects an open, a short to ground, or a short to power on the 1-2 shift solenoid valve circuits within 5 seconds.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL). |
| • | SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on the driver information center (DIC). |
| • | The PCM commands 2nd gear. |
| • | The PCM commands default line pressure. |
| • | The PCM inhibits TCC engagement. |
| • | The PCM freezes steady state adapts. |
| • | The PCM freezes garage shift adapts. |
| • | The PCM stores DTC P0753 in PCM history. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes. |
| • | A scan tool clears the DTC from PCM history. |
| • | The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring. |
| • | The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | Inspect the wiring at the PCM, the transmission 20-way connector, the 1-2 shift solenoid valve 2-way connector, and all other circuit connecting points for the following conditions: |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Reduced terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| - | Moisture intrusion |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
| • | Refer to Shift Solenoid Valve State and Gear Ratio table. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies that the 1-2 SS valve is operating and that an intermittent condition may have set the DTC.
-
This step isolates the automatic transmission wiring harness so that you can diagnose the engine wiring harness.
-
This step isolates circuit 1222 for an open.
-
This step isolates circuit 1222 of the engine wiring harness for a short to power.
-
This step isolates the engine wiring harness so that you may diagnose the automatic transmission wiring harness.
-
This step measures for a short to ground in circuit 1222.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||
2 |
Important: Before clearing the DTCs, 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 the PCM. Is DTC P0758 or P1860 set? | -- | ||||||
3 |
Refer to Wiring Repairs in Wiring Systems. Was the condition found? | -- | ||||||
4 |
Important: The condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics in Wiring Systems, for complete circuit distribution. Inspect circuit 839 of the engine wiring harness, for a short to ground. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | ||||||
5 |
Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | -- | |||||
|
Important: The condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics in Wiring Systems, for complete circuit distribution. Inspect circuit 839 of the engine wiring harness for an open. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | -- | ||||||
Using the scan tool, cycle the 1-2 shift solenoid ON and OFF three times. Listen at the transmission side cover. Does the 1-2 shift solenoid valve click when commanded ON? | -- | Go to Diagnostic Aids | ||||||
8 |
Is the test lamp ON? | -- | ||||||
Inspect circuit 1222 of the engine wiring harness for a short to ground. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | |||||||
10 | Cycle the 1-2 shift solenoid ON and OFF three times. Does the test lamp cycle ON and OFF as commanded? | -- | ||||||
Is the test lamp always OFF? | -- | |||||||
12 | Inspect circuit 1222 of the engine wiring harness for an open. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | ||||||
Inspect circuit 1222 of the engine wiring harness for a short to power. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | |||||||
14 |
Is the resistance value within the specified range? | 20-40 ohms | ||||||
15 | Is the resistance greater than the specified value? | 40 ohms | ||||||
Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | |||||||
17 | Measure the resistance from terminal A to the transmission case. Is the resistance less than the specified value? | 100 ohms | Go to Diagnostic Aids | |||||
18 | Inspect circuit 1222 of the automatic transmission wiring harness for a short to ground. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | ||||||
19 | Repair the wiring as necessary. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||
20 | Replace the automatic transmission wiring harness. Refer to Unit Repair. Is the replacement complete? | -- | -- | |||||
21 | Replace the 1-2 shift solenoid valve. Refer to Solenoid A Replacement. Is the replacement complete? | -- | -- | |||||
22 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |||||
23 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK |
