Circuit Description
The 1-2, 3-4 shift solenoid (1-2, 3-4 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, 3-4 SS valve is a normally-open exhaust valve located on the control valve body. Circuit 239 supplies ignition voltage to the 1-2, 3-4 SS valve. The output driver module, within the PCM, commands the solenoid ON or OFF by providing a ground path through circuit 1222. When the 1-2, 3-4 SS valve is commanded ON, the PCM senses low voltage. When the 1-2, 3-4 SS valve is commanded OFF, the PCM senses high voltage.
If the PCM detects a continuous open or a short to ground in circuit 1222 or the 1-2, 3-4 SS valve, then DTC P0753 sets. DTC P0753 is a type B DTC.
Conditions for Running the DTC
| • | The system voltage is 9-18 volts. |
| • | The engine speed is greater than 500 RPM for 5 seconds and not in fuel shut off. |
Conditions for Setting the DTC
DTC P0753 sets when either of the following conditions occurs for 5 seconds:
| • | The PCM commands the solenoid ON and voltage remains high (B+). |
| • | The PCM commands the solenoid OFF, and the voltage remains low (0 volts). |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the conditions for setting the DTC are met. |
| • | The PCM commands maximum line pressure. |
| • | The PCM freezes shift adapts. |
| • | The PCM inhibits 3-2 downshifts when the vehicle speed is greater than 48 km/h (30 mph). |
| • | 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 the PCM history. |
| • | The PCM clears the DTC from the PCM history if the vehicle completes 40 consecutive 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, 3-4 SS valve 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 |
| - | Corrosion |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
| • | Ensure that the scan tool commanded gear has correct solenoid states and ratio. |
| Refer to the Shift Solenoid Valve State and Gear Ratio table. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step isolates the fault between the engine harness and the transmission harness.
-
This step verifies that circuit 1222 is neither open nor shorted to power.
-
This step verifies that the 1-2, 3-4 shift solenoid (SS) valve has neither shorted across its windings nor increased its resistance.
-
Because of the harsh conditions inside the transmission, repairing the automatic transmission (A/T) wiring harness assembly is not acceptable. You must replace the A/T wiring harness assembly.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls | |
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 PCM. Are DTCs P0758 or P1860 set? | -- | ||
3 |
Was a 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. Refer to Wiring Repairs in Wiring Systems. Refer to Solenoids and Wiring Harness Replacement. Is the repair complete? | -- | -- | |
5 |
Refer to Wiring Repairs in Wiring Systems. Refer to Solenoids and Wiring Harness Replacement. Is the repair complete? | -- | -- | |
Refer to Automatic Transmission Inline Harness Connector End View . Important: Additional DTCs will set. Is the test lamp ON? | -- | |||
7 | Inspect circuit 1222 (LT GRN) of the engine harness for a short to ground. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||
Using the Scan Tool , cycle the 1-2, 3-4 solenoid ON and OFF three times. Does the test lamp cycle ON and OFF as commanded? | -- | |||
9 | Inspect circuit 1222 (LT GRN) of the engine harness for an open or a short to power. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||
Refer to Automatic Transmission Inline Harness Connector End View . Is the measured resistance within the specified range? | 19-24 ohms at 20°C (68°F) 24-31 ohms at 88°C (190°F) | |||
11 | Is the resistance greater than the specified value? | 100 ohms | ||
12 |
Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||
13 | Connect the J 39200 DMM from terminal A of the J 39775 jumper harness to ground. Is the resistance less than the specified value? | 100 ohms | Go to Diagnostic Aids | |
14 | Inspect A/T wiring harness assembly circuit 1222 (LT GRN) for a short to ground or short to power circuit 839 (RED). Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||
15 | Replace the 1-2, 3-4 SS valve. Refer to 1-2 Shift Solenoid Replacement. Is the replacement complete? | -- | -- | |
16 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |
Replace the Automatic Transmission Wiring Harness Assembly. Refer to Solenoids and Wiring Harness Replacement. Is the replacement complete? | -- | -- | ||
18 | Repair circuit 1222 (LT GRN) of the engine harness. Is the repair complete? | -- | -- | |
19 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK |
