P2709 Trouble Code Definition
A P2709 code denotes a problem in one specific shift solenoid. Automatic transmissions are computer controlled and use shift solenoids to actuate gear changes, managing the flow and transfer of fluid between hydraulic circuits and internal passages.
What a P2709 Code Means
While the conditions that trigger a code can vary from one manufacturer, year, or model to another, almost all vehicles select gear ratios based on information from throttle position, engine load, engine speed and vehicle speed. When the desired gear ratio doesn’t agree with the gear ratio detected in real time, the code will be stored and the malfunction indicator lamp (MIL) or Check Engine Light will illuminate. Sometimes, several failure cycles may be needed for the MIL to illuminate.
Common Causes for P2709 Code
A P2709 trouble code can result from:
- Failed shift solenoid
- Blocked hydraulic passages inside transmission
- Mechanical internal failures in transmission
- Dirty or contaminated fluid
- Failed PCM
- Failed transmission control module
Symptoms of P2709 Code
A P2709 code can display symptoms including:
- Harsh shifts
- Delayed transmission engagement
- Illuminated MIL or Check Engine Light
- Transmission slippage
- Transmission overheating
- Poor fuel economy
- Limp-in mode
A P2709 code can also be accompanied by other solenoid-related codes.
Diagnosing the P2709 Code
Any transmission problem diagnosis should start with an inspection of the transmission fluid dipstick, making sure the fluid level is topped off and that fluid is in good condition. If the fluid level is low, top off with manufacturer-approved fluid and run the unit long enough to determine where the leak is coming from.
Dirty or burned fluid is an indication that the transmission has been poorly maintained, and may have been operated with low fluid levels.
In case of burned-smelling fluid, drop the transmission pan and check for clutch material and other debris in the bottom of the pan. If such debris is present, the transmission will likely need a complete rebuild of hard and soft parts, a new torque converter and a fluid flush/fill in order to work properly again.
If debris isn’t present in the pan, look for any burned or shorted wiring and replace connectors and circuits as needed. In most cases it will be necessary to replace the entire internal wiring harness of the transmission.
If the system wiring and connectors appear to be OK, connect a scanner to the diagnostic port. Record trouble codes. Clear the codes and operate the vehicle to see if the code returns. If the code doesn’t return, this could indicate an intermittent condition which may be tricky to diagnose. In some cases, the condition may have to be allowed to worsen in order to make a proper diagnosis.
If the transmission seems to operate normally and codes don’t register again, the problem may have been due to low fluid level/pressure. If the code returns and you notice slippage with the transmission fluid level topped off, check the pump’s pressure with a manual pressure gauge.
Find a hydraulic pressure diagram for the vehicle and connect the gauge to the opening at the transmission housing in order to get a pump pressure reading. Compare your readings with manufacturer’s specs and make repairs as needed.
Low pump pressure can be due to clogged internal passages, faulty shift solenoids, faulty electronic pressure regulator or a defective pump.
If the transmission seems to be operating normally but the code returns immediately, suspect the shift solenoid. Check reference voltage and ground signals using a digital volt/ohmmeter. Disconnect all other related control modules before checking circuit resistance, to avoid damage to other components.
Replace any circuits/connectors as needed and retest system. Use the manufacturer’s wiring diagram for the shift solenoid involved, then test the solenoid and all other related circuits for resistance and continuity. Compare readings with manufacturer’s specs. Repair/replace circuitry, connectors or components that do not fall within manufacturer’s specs.
Retest the system afterward. If all system circuits are within spec, connect the scanner to the vehicle’s diagnostic port and see if you can manually engage the shift solenoids in question.
If the solenoid still won’t activate manually, replace the solenoid or solenoid pack. If the solenoid functions properly and all circuits are OK, suspect the PCM—but keep in mind that PCMs rarely fail, and replacement of the PCM will also require reprogramming.
Need help with a P2709 code?
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