P0702: Transmission Control System Electrical
What to do
The transmission has probably defaulted to a fixed gear to protect itself. That default is meant to get you home, not to be driven on — the converter is unlocked in that state and generates heat the cooler was never sized for. Keep the journey short and avoid motorway speeds.
What this code means
An electrical fault in the transmission control system rather than a hydraulic one — supply, ground, or a circuit the module drives. Where P0701 says the transmission did not do as it was told, P0702 says the module cannot properly command it in the first place.
The pattern worth knowing is that one shorted solenoid can take down the whole set. Shift solenoids are typically driven from a shared supply or a shared driver stage inside the module, so a single winding that has shorted internally pulls that supply down and every solenoid on it stops responding. The result is a code implicating the entire control system and a transmission in limp mode, from one inexpensive failed part. Measuring each solenoid's resistance individually separates that case from a genuine module failure, and it is worth doing before a module is replaced.
Likely causes
Start here
- Short circuit in a transmission solenoid · moderate
- Damaged transmission wiring harness · moderate
- Corroded transmission connector · moderate
Less common
- Poor module ground connection · moderate
- Fluid tracking into the transmission connector · moderate
- Faulty transmission control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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