The P0739 trouble code indicates that the Transmission Control Module (TCM) has detected a high voltage condition in the engine speed output circuit. The TCM monitors the engine speed to ensure proper operation of the transmission. If it detects a high voltage condition in the engine speed output circuit, it will trigger this trouble code and illuminate the Check Engine Light (CEL).
TCM Engine Speed Output Circuit High
Code symptoms P0739.
1. Check Engine Light (CEL) illuminated on the dashboard.
2. Engine may hesitate or stumble during acceleration.
3. Transmission may shift harshly or erratically.
4. Decreased fuel efficiency.
5. Vehicle may go into “limp mode” to prevent further damage.
This code is common in brands such as:: Chevrolet, Renault, Ford, Toyota, Nissan, Mercedes Benz, Honda.
Causes of the code P0739.
1. Faulty engine speed sensor.
2. Wiring or connector issues in the engine speed sensor circuit.
3. Faulty TCM.
4. ECM software issues.
5. Internal TCM hardware problems.
Code Solutions P0739.
1. Perform a visual inspection of the wiring and connectors associated with the engine speed sensor circuit. Repair or replace any damaged or corroded connections.
2. Test the engine speed sensor using a multimeter to ensure it is functioning properly. Replace the sensor if it’s faulty.
3. Perform a diagnostic scan of the TCM to retrieve freeze frame data and any stored trouble codes. This can provide valuable information about the specific conditions under which the code was set.
4. Check for any software updates or recalls related to the TCM or ECM. Update the software if necessary.
5. If the problem persists after addressing these potential causes, further diagnosis may be required. This may involve testing the TCM for proper operation, checking for internal hardware issues, or using advanced diagnostic tools to pinpoint the problem.