P0969 – Pressure control (PC) solenoid C -control circuit range/ performance
By (Contact Me)
Last Updated 2016-09-06
ASE Master Tech
| Trouble Code | Fault Location | Probable Cause |
|---|---|---|
| P0969 | Pressure control (PC) solenoid C -control circuit range/ performance | Wiring, poor connection, pressure control solenoid, ECM/PCM/TCM |
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What Does Code P0969 Mean?
If your vehicle has exhibited an illuminated malfunction indicator lamp (MIL), and has stored a code P0969, it means that the powertrain control module (PCM) has detected a problem with a specific electronic pressure control solenoid (EPCS) or solenoid circuit for the automatic transmission. The designation C usually refers to a tertiary EPCS/circuit. This code is used exclusively in vehicles equipped with automatic transmissions. Automatic transmissions in OBD-II vehicles are controlled electronically by the PCM or a stand-alone controller, called a transmission control module (TCM). Most transmission controllers are integrated into the PCM. The major components of the transmission control system are:- Control module
- Controller area network (CAN)
- Numerous sensors and solenoids
- A powerful hydraulic pump
- One or more electronic pressure control solenoid/s
- An assortment of shift solenoids
- A torque converter clutch solenoid
- A hydraulic valve body
The transmission controller receives input signals from various engine and transmission sensors. Engine sensor inputs typically include the degree of throttle angle, engine RPM, engine coolant temperature, and engine load percentage. Transmission sensor inputs are designed to monitor transmission input speed (RPM), transmission output speed (RPM), shifter position, torque converter lock-up percentage, vehicle speed, transmission temperature, and pump pressure. This is not an exhaustive list. These input signals are used by the transmission controller to aid in mapping shift strategy and electronic pump pressure parameters.
The electronic pressure control solenoid/valve (usually located in the valve body) is used to regulate pump pressure. Careful regulation of pump pressure keeps the transmission shifting smoothly and precisely. Maximum pump pressure - applied directly to the valve body - would lead to extremely harsh shifting and potential driveline damage.
If the PCM detects that it cannot regulate pump pressure (by applying the appropriate degree of voltage to the EPCS) or detects a level of EPCS circuit voltage/resistance that is not within programmed specifications, a P0969 will be stored and a MIL may be illuminated.
What are the common causes of code P0969 ?
- Transmission (front) pump failure
- Open or shorted wiring or connectors in the EPCS circuit
- Defective electronic pressure control solenoid
- Low or subpar transmission fluid
What are the symptoms of code P0969 ?
- Delayed transmission engagement
- Erratic transmission shifting
- The transmission may fail to shift
- Harsh transmission shifting
- A loud whining noise from the transmission torque converter/bell housing area
How do you troubleshoot code P0969 ?
To accurately diagnose a code P0969, you will need a diagnostic scanner (scan tool), a digital volt/ohmmeter (DVOM), a transmission pressure gauge, and vehicle factory digrams and information (All Data DIY). I like to begin my diagnosis with a visual inspection of transmission control wiring and connectors. Remember that a large segment of the transmission control harness is inside the transmission hosing.
A P0969 code may be attributed to an electronic malfunction or a mechanical malfunction. If the transmission is low on fluid, it could cause a low pressure condition and a stored P0969. Check the transmission fluid and refill it (always use the recommended fluid) if necessary. If the fluid level was low, you will also want to inspect the transmission, transmission cooler, and transmission cooling lines for leaks. Remove the dipstick (if applicable) and see if the fluid smells and looks burnt. If it appears burnt, suspect mechanical transmission failure, which will require an overhaul.
If the transmission fluid is significantly low (more than 2-quarts), you will need to locate the leak and repair it, Refill the transmission with the recommended fluid and test drive the vehicle to see if the problem persists and the code is reset. If the code is reset, use the transmission pressure gauge to check pump pressure. If the pump has been operated without enough fluid, it could have been damaged creating a low pressure condition that will also require a transmission overhaul.
Once the transmission leak has been repaired and it is refilled with clean fluid, connect the scan tool to the vehicle diagnostic connector and retrieve all stored codes and freeze frame data. Write this information down because it will prove helpful later. Clear the codes and test drive the vehicle (if possible).
If the code is reset, use the transmission pressure gauge to obtain a manual pressure reading. Consult your repair guide (All Data DIY) for pressure test recommendations. Compare this reading with manufacturer’s specifications. If fluid pressure is too low, suspect a mechanical failure. I pressure is within specs, you will likely discover that a defective EPCS or wiring malfunction are at the root of your malfunction.
Once you have located the EPCS (and gained access to it) use the DVOM to test resistance values. Compare your actual findings with manufacturer’s specifications and replace the solenoid if it doesn’t comply.
Disconnect all related controllers prior to testing circuit resistance (with the DVOM) in order to avoid controller damage.
Codes Related to P0969
- P0700 Transmission Control System Malfunction
- P0701 Transmission Control System Range/Performance
- P0702 Transmission Control System Electrical
- P0745 Pressure Control Solenoid Malfunction
- P0746 Pressure Control Solenoid Performance or Stuck Off
- P0747 Pressure Control Solenoid Stuck On
- P0748 Pressure Control Solenoid Electrical
- P0749 Pressure Control Solenoid Intermittent
- Any other transmission control codes
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