Circuit Description
The 1-2 shift solenoid valve (1-2 SS Valve) controls the transmission fluid pressure on the 1-2 shift valve. Circuit 1039 provides ignition voltage to the solenoid. The powertrain control module (PCM), commands the solenoid ON and OFF by closing and opening the ground, and monitors voltage levels. When the 1-2 SS valve is commanded ON, the PCM detects a low voltage. When the 1-2 SS Valve is 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. DTC P0753 is a type B DTC.
Conditions for Running the DTC
| • | System voltage is 10-18 volts. |
| • | The engine speed is greater than 500 RPM. |
| • | Not in fuel shut off. |
Conditions for Setting the DTC
DTC P0751 sets if one of the following conditions exists for 5 seconds:
Condition 1
The PCM commands the solenoid ON and the voltage signal to the PCM remains high (B+).
Condition 2
The PCM commands the solenoid OFF and the voltage signal to the PCM 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 exist for setting the DTC. |
| • | The PCM inhibits commanded 3-2 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 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 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 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 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 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 checks if engine harness circuit 1222 is open.
-
This step checks if the solenoid and transmission circuit is within resistance specifications. Lower than expected readings indicate a short together on the control side of the internal transmission harness.
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. Are DTCs P0740, P0758 or P1860 set also? | -- | ||||||||||||||||
3 |
Refer to Wiring Repairs in Wiring Systems. Was a condition found and corrected? | -- | ||||||||||||||||
4 | Inspect for a short to ground in engine harness circuit 1039 (PNK) or transmission harness circuit 839 (RED). Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | -- | |||||||||||||||
5 | Inspect for an open in engine harness circuit 1039 (PNK) or transmission harness circuit 839 (RED). Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | -- | |||||||||||||||
Refer to Automatic Transmission Inline Harness Connector End View . Is the test lamp ON? | -- | |||||||||||||||||
7 | Repair the open in ignition feed circuit 1039 (PNK) to the transmission connector. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||||||||||||
Does the test lamp turn ON and OFF? | -- | |||||||||||||||||
9 | Inspect circuit 1222 (LT GRN) of the engine wiring harness for an open, short to ground or short to power. Refer to General Electrical Diagnosis in Wiring Systems. Did you find an open or short condition? | -- | ||||||||||||||||
10 |
Is the measured resistance within the specified range? | 19-31ohms | ||||||||||||||||
Connect a DMM from jumper terminal A to terminals B, C, D, F and the transmission case. Are all resistances greater than the specified value? | 29 ohms @ 20° C (68° F) 37 ohms @ 88° C (190° F) | |||||||||||||||||
12 | Is the resistance greater than the specified value? | 31 ohms | ||||||||||||||||
13 | Inspect the transmission harness circuits 839 (RED) and 1222 (LT GRN) for an open. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||||||||||||||||
14 | Disconnect wiring harness from the 1-2 shift solenoid. Connect DMM from jumper terminal A to terminal E. Is the resistance greater than the specified value? | 100 ohms | ||||||||||||||||
15 | Replace the transmission wiring harness. Refer to Solenoids and Wiring Harness Replacement . Is the replacement complete? | -- | -- | |||||||||||||||
16 | Replace the 1-2 shift solenoid valve. Refer to 1-2 Shift Solenoid Valve Replacement . Is the replacement complete? | -- | -- | |||||||||||||||
17 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |||||||||||||||
18 | Repair the wiring as needed. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||||||||||||
19 | Perform the following in order to verify the repair:
Has the test run and passed? | -- | System OK |
