Circuit Description
The 1-2 Shift Solenoid Valve Assembly (1-2 SS Valve Assy.) controls the transmission fluid pressure on the 1-2 shift valve. Circuit 1339 provides ignition voltage to the solenoid. The Output Driver Module (ODM), within the Powertrain Control Module (PCM), commands the solenoid ON and OFF by closing and opening the ground. The PCM monitors voltage levels at the ODM. When commanded, the 1-2 SS Valve Assy. is commanded ON, the PCM detects a low voltage. When commanded OFF, the PCM detects a high voltage.
DTC P0753 sets if the received voltage is outside the calibration limits, indicating an open or short to ground. DTC P0753 is a type A DTC.
Conditions for Setting the DTC
| • | System voltage is 10-16 volts. |
| • | The engine speed is greater than 500 RPM. |
| • | Not in fuel shut off. |
| • | The PCM commands the solenoid ON and the voltage signal to the PCM remains high (B+). |
| • | The PCM commands the solenoid OFF and the voltage signal to the PCM remains low (0 volts). |
| • | All conditions are met for 5 seconds. |
Action Taken When the DTC Sets
| • | The PCM illuminates the Malfunction Indicator Lamp (MIL). |
| • | The PCM inhibits downshifts to 2nd gear if the vehicle speed is greater than 48 km/h (30 mph). |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL after three consecutive trips without a failure reported. |
| • | A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported. |
| • | The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | Inspect the wiring at the PCM, the transmission connector, 1-2 shift solenoid connector and all other circuit connecting points for the following conditions: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| - | Moisture intrusion |
| - | Corrosion |
| • | When diagnosing for an intermittent short or open condition, 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 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 shift solenoid has neither shorted across its windings nor increased its resistance.
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 for reference. The Clear Info function will erase the data. Are DTCs P0758, P1860 or P0740 set? | -- | ||||||||||||||||
3 |
Was a condition found and corrected? | -- | ||||||||||||||||
4 | Repair short to ground in engine harness circuit 1339 or transmission harness circuit 839. Refer to General Electrical Diagnosis . Was a condition found and corrected? | -- | -- | |||||||||||||||
5 | Repair the open in engine harness circuit 1339 or transmission harness circuit 839. Refer to General Electrical Diagnosis . Was a condition found and corrected? | -- | -- | |||||||||||||||
Important: Additional DTCs will set. Is the test lamp ON? | -- | |||||||||||||||||
7 | Inspect engine harness circuit 1222 for a short to ground. Refer to General Electrical Diagnosis . Was a condition found and corrected? | -- | ||||||||||||||||
Using the scan tool command the 1-2 solenoid ON and OFF three times. Does the test lamp cycle ON and OFF as commanded? | -- | |||||||||||||||||
9 | Inspect engine harness circuit 1222 for an open. Refer to General Electrical Diagnosis . Was a condition found and corrected? | -- | ||||||||||||||||
10 | Inspect engine harness circuit 1222 for a short to power. Refer to General Electrical Diagnosis . Was a condition found and corrected? | -- | ||||||||||||||||
Is the measured resistance within the specified range? | 19 ohms to 31 ohms | |||||||||||||||||
12 | Is the resistance greater than the specified value? | 31 ohms | ||||||||||||||||
13 | Inspect the transmission harness RED wire circuit 839 and the LT GRN wire circuit 1222 for an open. Refer to General Electrical Diagnosis . Was a condition found? | -- | ||||||||||||||||
14 | Replace the Automatic Transmission Wiring Harness. Refer to Solenoids and Wiring Harness Replacement . Is the replacement complete? | -- | -- | |||||||||||||||
15 | Connect the J 39200 Digital Multimeter from terminal A of the jumper to ground. Is the resistance less than the specified value? | 100 ohms | ||||||||||||||||
16 | Inspect the transmission harness LT GRN wire circuit 1222 for a short to ground or short to power. Refer to General Electrical Diagnosis . Was a condition found? | -- | ||||||||||||||||
17 | Replace the Automatic Transmission Wiring Harness. Refer to Solenoids and Wiring Harness Replacement . Is the replacement complete? | -- | -- | |||||||||||||||
18 | Replace the 1-2 Shift Solenoid Valve Assembly. Refer to Solenoids and Wiring Harness Replacement . Is the replacement complete? | -- | -- | |||||||||||||||
19 | Inspect PCM connector C1 (Blue) for bent, damaged or backed out connector pins. Was a condition found and corrected? | -- | ||||||||||||||||
20 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the replacement complete? | -- | -- | |||||||||||||||
21 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
