Circuit Description
The 1-2 shift solenoid (SS) valve controls the fluid flow action on the 1-2 and the 3-4 shift valves. The 1-2 SS valve is a normally-open exhaust valve that is used with the 2-3 SS valve to allow for four different shifting combinations. The 1-2 SS valve attaches to the control valve body within the transmission. The ignition voltage goes directly to the 1-2 SS valve. The PCM controls the 1-2 SS Valve by providing the ground path through CKT 1222.
When the powertrain control module (PCM) detects a continuous open or short in the 1-2 SS valve circuit or the 1-2 SS valve, then DTC P0753 sets. DTC P0753 is a type D DTC. For California emissions vehicles, DTC P0753 is a type A DTC.
Conditions for Running the DTC
| • | The system voltage is 8.0-18.0 volts. |
| • | The ignition is ON. |
| • | The engine runs more than 300 RPM for greater than 7 seconds. |
Conditions for Setting the DTC
All conditions for running the DTC are met, and either of the following conditions occur for 4.3 out of 5 seconds.
| • | The PCM commands the solenoid on, and the voltage input remains high (B+). |
| • | The PCM commands the solenoid off and the voltage input remains low. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) for California emissions vehicles. |
| • | The PCM commands maximum line pressure. |
| • | The PCM freezes shift adapts. |
| • | The PCM inhibits 3-2 downshifts above 25 MPH. |
| • | The PCM stores DTC P0753 in PCM history. |
Conditions for Clearing the MIL/DTC
| • | For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes. |
| • | A scan tool can clear the MIL/DTC. |
| • | For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without an emission related diagnostic fault occurring. |
| • | For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-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 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. |
| • | An open ignition feed on CKT 1020 can cause multiple DTCs to set. |
| • | First diagnose and clear any engine DTCs or TP sensor codes that are present. Then inspect for any transmission DTCs that may have reset. |
| • | 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 tests the function of the 1-2 SS valve and the internal wiring harness.
-
This step tests the power to the 1-2 SS valve from the ignition through the fuse.
-
This step tests the ability of the PCM and the wiring to control the ground circuit.
-
This step measures the resistance of the automatic transmission wiring harness assembly and the 1-2 SS valve.
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. Were DTCs P0753, P0758, or P1860 also set? | -- | ||||||||
3 |
Refer to Wiring Repairs in Wiring Systems. Was the condition corrected? | -- | ||||||||
Using the transmission output control function on the scan tool, command the 1-2 SS valve ON and OFF three times while listening to the bottom of the transmission pan (use a stethoscope if needed). Does the solenoid click when commanded? | -- | Go to Diagnostic Aids | ||||||||
Is the test lamp on? | -- | |||||||||
6 | Repair the open or high resistance in ignition feed CKT 1020 (PNK) to the 1-2 SS valve. Refer to Wiring Repairs in Wiring Systems. Was the condition corrected? | -- | -- | |||||||
Does the test lamp illuminate when you command the shift solenoid ON and turn off when you command the shift solenoid OFF? | -- | |||||||||
8 | Inspect CKT 1222 (LT GRN) for an open or short to ground. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | ||||||||
9 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |||||||
10 |
Is the resistance within the specified range? | 19-31Ω | ||||||||
11 |
Is the resistance within the specified range? | 19-31Ω | ||||||||
12 |
Are both readings greater than the specified value? | 250kΩ | Go to Diagnostic Aids | |||||||
13 |
Are both readings greater than the specified value? | 250kΩ | ||||||||
14 | Replace the automatic transmission wiring harness assembly. Refer to Wiring Harness Replacement. Is the replacement complete? | -- | -- | |||||||
15 | Replace the 1-2 SS valve. Refer to Control Valve Body Replacement. Is the replacement complete? | -- | -- | |||||||
16 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK |
