P2779

Downshift Switch Circuit Range/Performance

Severity

⚠️ Medium

Can you drive?

Yes, but get it checked soon

Approx. repair cost

$17–89 (est.)

Symptoms

Inability to downshift
Incorrect operation of the low gear mode
Turning on the emergency mode of the gearbox
Check Engine Light or Transmission Malfunction Is On
Reduced vehicle dynamics when driving downhill

Causes

Downshift switch malfunction
Open or short circuit in wiring
Contact problems or terminal oxidation
Transmission control module (TCM) malfunction
Problems with the control unit software

How to Fix

Check the downshift switch for malfunctions
Check the integrity of the wiring and the condition of the contacts
Diagnose the transmission control module (TCM)
If necessary, replace or reprogram the control unit

Related codes