P0785: Shift/Timing Solenoid DTC Trouble Code

In order to handle transmission fluid being transferred from one hydraulic circuit to another, the ECU uses little spring-loaded plunger devices known as shift timing solenoids. If the computer does not think the data coming from the shift/timing solenoid is appropriate for the situation, it will store a P0785 diagnostic trouble code.

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What Transmission Do I Have?

How Serious is the Code?

The symptoms of a P0785 DTC may not seem very serious at first, but they will eventually progress to the point that the vehicle cannot be driven safely.

Symptoms

Symptoms of a P0785 include:

• Check engine light
• Delayed, harsh or erratic shifts
• Limp mode
• Slipping through the gears
• Getting ‘stuck’ in a gear
• Vehicle won’t move when in gear
• Transmission overheats
• Decreased fuel economy

Causes

• Low transmission fluid
• Dirty transmission fluid / filter
• Frayed wiring / damaged connectors
• Failed shift timing solenoid
• Pressure blockage
• TCM or ECU failure

How to Diagnose the Code?

Because an OBD2 trouble code referring to shift solenoids, relates to pressure issues. The level and quality of transmission fluid needs to be considered when starting to diagnose a shift timing solenoid diagnostic trouble code. Dirty ATF is often a sign of internal problems, which may require a replacement or remanufactured transmission. Performing a transmission flush can sometimes provide a temporary fix. But if major damage to the transmission pump, valve body or torque convertor has already happened, it might not make any difference.

If there are no issues with the condition of the transmission fluid, then the wiring and connectors will need to be inspected before testing the solenoid directly. If testing finds no fault with the shift timing solenoid, then the valve body should be considered.

Common Mistakes When Diagnosing

Often times, a shift timing solenoid OD2 trouble code can be caused by in an electrical short, or a blocked hydraulic passage.

What Repairs Will Fix P0785?

• Changing the transmission fluid and filter
• Replace faulty shift timing solenoid
• Perform transmission flush to clean passages
• Cleaning corrosion from connectors
• Repairing or replacing wiring
• Flash or replace PCM/TCM

Related Codes

P0786 – Shift/Timing Solenoid Range/Performance

P0787 – Shift/Timing Solenoid Low

P0788 – Shift/Timing Solenoid High

P0789 – Shift/Timing Solenoid Intermittent

Need a replacement transmission? Get an estimate for replacement transmissions and local installation. Look up your transmission model by vehicle make and model.

What Transmission Do I Have?

Full Transmission DTC Codes Table