DTC P0964 Pressure Control Solenoid 2 (PCS2) Control Circuit Open
P0964 - Pressure Control Solenoid 2
Circuit Description
Pressure Control Solenoid 2 (PCS2) is a normally open solenoid used to apply the C2 clutch in fourth through sixth range, and the C3 clutch in Reverse. The TCM commands the solenoid OFF to produce hydraulic pressure in the clutch apply circuit. When PCS2 is commanded ON, the C2 clutch is released.
The TCM sends control current to PCS2 from High Side Driver 2 (HSD2) via wire 171. HSD2 is continuously ON unless the TCM detects a fault condition. The Transmission Control Module (TCM) regulates the amount of current to PCS2 by switching PCS2 Low Side Driver (LSD) ON and OFF. Wire 152 completes the circuit between PCS2 and its LSD. DTC P0964 indicates that the TCM has detected an open condition in PCS2 electrical circuit. The open condition may exist in the high side (wire 171) or low side (wire 152).
Conditions for Running the DTC
• The components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 9V and less than 32V (24V TCM).
• TCM initialization is in process or engine speed is greater than 200 rpm and less than 7500 rpm for 5 seconds.
Conditions for Setting the DTC
DTC P0964 sets when the TCM detects an open circuit on the PCS2 return circuit for more than 2 seconds.
Actions Taken When the DTC Sets
When DTC P0964 is active, the following conditions occur:
• The CHECK TRANS light illuminates.
• DTC is stored in TCM history.
• Hydraulic default (SOL OFF) is commanded. The shift selector position and hydraulic state of latch valves determines the range attained.
Conditions for Clearing the DTC/CHECK TRANS Light
Use the Allison DOC™ For PC–Service Tool to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without failure.
Diagnostic Aids
• DTC P0964 indicates an open in the electrical circuit for the PCS2 solenoid. In addition to PCS2, HSD2 also supplies power to solenoids PCS1, PCS3, and SS1. If DTC P0964 is accompanied by DTC P2727 (PCS1 open circuit) and/or DTC P0968 (PCS3 open circuit), the open is most likely in the high side of the circuit.
• You may have to drive the vehicle in order to experience a fault. Use the data obtained from failure records to determine transmission range and/or certain vehicle operating variables such as temperature, run time etc. This data can be useful in reproducing the failure mode when DTC was set.
• Inspect the wiring for poor electrical connections at the TCM and transmission connector. Look 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
• Inspect OEM wiring harness routing, look for possible contact points where chafing could occur leading to an open or short circuit condition. Moving parts on the vehicle could be contacting the harness; this includes parking brake drum, suspension components, etc.
• When diagnosing for an intermittent short or open, massage the wiring harness while watching the test
equipment for a change.
#Test Description
This DTC requires the use of the J 47275 TCM Breakout and J 47279 Transmission Breakout. The numbers below refer to step numbers on the diagnostic table.
2. Tests for the proper ignition voltage.
→Install the Allison DOC™ For PC–Service Tool.
→Start the Engine.
→Record the failure records.
→Monitor ignition voltage. Is the voltage within the specified values? 9–18V for 12V TCM, and 18–32V for 24V TCM.
3. Tests for an active DTC.
→Clear the DTC.
→Start the Engine and test drive the vehicle.
→Attempt to duplicate the same conditions observed in the failure records (range attained, temperature, etc.). NOTE: This DTC detects an open condition in the PCS2 electrical circuit. Did DTC P0964 return?
4. Tests the OEM harness for an excessive voltage drop caused by open condition in either wire 171 or wire 152 of the OEM chassis harness.
→Turn ignition OFF.
→Install J 47275 TCM Breakout between the OEM and TCM 80-way connectors.
→Install J 47279 Transmission Breakout between the OEM and transmission 20-way connectors.
→Turn ON the ignition, leave Engine OFF.
→Using Allison DOC™ For PC–Service Tool, enter solenoid test mode and command PCS2 ON. Read More: Solenoid Test using ALLISON DOC Software (ALLISON Transmission).
→Determine the voltage drop in the high side of the PCS2 circuit as follows:
• At J 47275-1 TCM Overlay, measure voltage between pin 71 and an isolated ground.
• At J 47279-1 Transmission Overlay, measure voltage between pin 6 and an isolated ground.
• Subtract the two voltage measurements to obtain the voltage drop in the circuit.
→Determine the voltage drop in the low side of the PCS2 circuit as follows:
• At J 47275-1 TCM Overlay, measure voltage between pin 52 and an isolated ground.
• At J 47279-1 Transmission Overlay, measure voltage between pin 5 and an isolated ground.
• Subtract the two voltage measurements to obtain the voltage drop in the circuit. NOTE: A voltage drop of more than 0.5V across either circuit indicates an excessive voltage loss in the OEM harness. Did either high-side or low-side voltage drop exceed 0.5VDC?
6. Tests for an open condition in the transmission internal harness.
→Turn ignition OFF.
→Disconnect the OEM 20-way connector from J 47279 Transmission Breakout. Leave the transmission 20-way connector connected to the breakout.
→Using a digital multimeter (DVOM), measure the resistance between pin 5 and pin 6 of the transmission 20-way connector. Is the resistance within the specified value?
7. Tests for the proper PCS2 resistance.
→Remove the hydraulic control module assembly.
→Disconnect PCS2 from the internal wiring harness.
→Using a DVOM, measure PCS2 resistance at pins A and B. Is resistance within the specified values? (4.0 to 7.8 ohms).
→Replace the internal wiring harness. Is the replacement complete?
→Replace PCS2. Is the replacement complete?
To verify the repair:
1. Clear the DTC.
2. Drive the vehicle under normal operating conditions.
Did the DTC return?
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