What Does It Mean?
This is a generic diagnostic trouble code (DTC) and generally applies to OBD-II equipped vehicles with an automatic transmission.
This may include, but is not limited to, vehicles from Chrysler, Ford, Dodge, Hyundai, Kia, Ram, Lexus, Toyota, Mazda, Honda, VW, etc. Although generic, the exact repair steps may vary by year, make, model, and powertrain configuration.
Most automatic transmissions incorporate a number of shift solenoids, depending on the number of gears inside. Related trouble codes for the “D” shift solenoid are codes P0765, P0766, P0767, P0768, and P0769 depending on the specific malfunction that alerts the PCM to set the code and illuminate the Check Engine light. If you have an Overdrive light or other transmission warning light, it may also be illuminated.
The purpose of the shift solenoid circuit is for the PCM to monitor the shift solenoids to manage fluid movement between different hydraulic circuits and change the gear ratio at the appropriate time. This process maximizes engine performance levels at the lowest possible RPM.
The automatic transmission relies on bands and clutches to shift gears, and this is accomplished by having fluid pressure in the right place at the right time. Transmission solenoids are responsible for opening or closing valves in the valve body to allow transmission fluid to flow to the clutches and bands to move the transmission smoothly as the engine accelerates.
When the Powertrain Control Module (PCM) detects a malfunction in the “D” shift solenoid circuit, a variety of codes can be triggered depending on the specific vehicle, transmission, and number of gears incorporated in the specific automatic transmission. In this case, OBD-II trouble code P0768 is associated with an electrical malfunction in the transmission “D” shift solenoid circuit.
How Severe Is This DTC?
The severity of this code normally starts as moderate, but it can escalate to a more severe level quickly when not corrected in a timely manner.
What Are Some of the Symptoms of the Code?
Symptoms of a P0768 trouble code may include:
Transmission slipping
Transmission overheating
Transmission shifting harshly
Reduced fuel economy
Symptoms
potentially missed shifts
Vehicle enters limp mode
Check Engine light illuminated
What Are Some of the Common Causes of the Code?
Causes
of this P0768 transmission code may include:
Insufficient fluid level
Dirty or contaminated fluid
Dirty or clogged transmission filter
Faulty transmission valve body
Restricted hydraulic passages
Transmission has internal failure
Faulty shift solenoid
Corroded or damaged connector
Faulty or damaged wiring
Faulty PCM
What Are the P0768 Troubleshooting Steps?
Before starting the troubleshooting process for any malfunction, you should research Technical Service Bulletins (TSBs) for the specific vehicle by year, model, and transmission. In some circumstances, this can save you a lot of time in the long run by pointing you in the right direction. You should also check the vehicle’s records to verify the last time the filter and fluid were changed if possible.
Fluid and Wiring Inspections
The first step is to ensure the fluid level is correct and inspect the condition of the fluid for any contamination. Next, a thorough visual inspection to check the associated wiring for obvious defects such as scraping, rubbing, bare wires, or burn spots should be performed.
Next, check the connectors and connections for security, corrosion, and damaged pins. This process should include all wiring and connectors for the transmission solenoids, transmission pump, and PCM. Based on the configuration, the transmission bonding should be inspected for security and bonding issues.
Advanced Steps
Advanced steps become very vehicle-specific and require appropriate advanced equipment to operate accurately. These procedures require a digital multimeter and the vehicle-specific technical references. Voltage requirements will be highly based on the specific year and model of the vehicle. You must follow the troubleshooting chart specific to your vehicle.
Continuity Checks
Continuity checks should always be performed with the power disconnected from the circuit, and normal readings for wiring and connections should be 0 ohms of resistance, unless otherwise indicated by the technical data. Resistance or lack of continuity is an indication of faulty wiring that is open or shorted and must be repaired or replaced.
What Are the Common Repairs for This Code?
Replacing fluid and filter
Repairing or replacing a faulty shift solenoid
Repairing or replacing the faulty transmission valve body
Repairing or replacing the faulty transmission
Flushing the transmission to clean passages
Cleaning corrosion from connectors Repairing or replacing wiring
Reprogramming or replacing PCM
I hope the information in this article has been helpful in pointing you in the right direction to correct the issue with your shift solenoid circuit error code. This article is strictly informational, and the technical data and service bulletins specific to your vehicle should always take priority.