P0783: 3-4 Shift Malfunction DTC Trouble Code

The P0783 diagnostic trouble code is triggered when there is a problem with the 3-4 shift function.

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What Transmission Do I Have?

How Serious is the Code?

A P0783 might not seem like a big deal at first, but the problems can get a lot worse, and more expensive if you don’t get it seen about.

Symptoms

Symptoms of a P0783 include:

• Check engine light
• Unusually hard or erratic shifting
• Transmission slipping between 3rd and 4th gears
• Transmission will not change between 3rd and 4th gears
• Increased fuel consumption
• Overheating
• Limp Mode

Causes

• Insufficient transmission fluid
• Dirty transmission fluid / filter
• Frayed wiring / damaged connectors
• Failing 3-4 shift solenoid
• Failing transmission pump
• Internal pressure problems
• Valve body issue
• ECU or TCM failure

How to Diagnose the Code?

If the transmission fluid contains any dirt, sludge or metallic debris, the solenoids may not function properly. The presence of metal shavings could also indicate internal component failure, which is why checking the ATF level and condition should be the first step in diagnosing a transmission solenoid fault code. If the fluid is dirty and pressure blockages are suspected, then a transmission flush may be performed.

If there are no obvious maintenance related issues, then the wiring and connectors should be checked for evidence of damage and/or corrosion. If everything appears fine, then the 3-4 shift solenoid will need to be tested according to the manufacturer’s procedure. If no issues have been found by this point, then the problem could lie with the transmission pump, valve body, or pressure regulator.

Common Mistakes When Diagnosing

Even though most automatic transmissions operate in a similar fashion, not all the components work in the same way. Depending on the age and type of vehicle, the different types of solenoids can require different testing procedures to get accurate results.

What Repairs Will Fix P0783?

• Change the transmission fluid and filter
• Replace faulty solenoid(s)
• Repair or replace a faulty transmission pump
• Repair or replace defective transmission valve body
• Transmission flush to clean passages
• Cleaning corrosion from connectors
• Repairing or replacing wiring
• Flashing or replacing ECU / TCM

Related Codes

P0780 – Shift Malfunction

P0781 – 1-2 Shift Malfunction

P0782 – 2-3 Shift Malfunction

P0784 – 4-5 Shift Malfunction

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