Possible causes
– Low transmission fluid level
– Dirty transmission fluid
– Faulty Reduction solenoid valve
– Reduction solenoid valve harness is open or shorted
– Reduction solenoid valve circuit poor electrical connection
– Dirty transmission fluid
– Faulty Reduction solenoid valve
– Reduction solenoid valve harness is open or shorted
– Reduction solenoid valve circuit poor electrical connection
When is the code detected?
The P0770 code is detected when the ECM detects an improper voltage drop when it tries to operate the solenoid valve.
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
– Transmission will not shift gears.
– Transmission will not shift gears.
P0770 HYUNDAI Description
Reduction solenoid valve is turned ON or OFF by the Transmission Control Module (TCM) in response to signals sent from the park/neutral position (PNP) switch, vehicle speed and Engine Control Module (ECM) (throttle opening). Gears will then be shifted to the optimum position.
HYUNDAI Technical Service Bulletins for P0770 code
1999 HYUNDAI SONATA ENGINE AND ENGINE COOLING:ENGINE
2001 HYUNDAI SANTA FE ENGINE AND ENGINE COOLING:ENGINE
2001 HYUNDAI XG ENGINE AND ENGINE COOLING:ENGINE
2003 HYUNDAI TIBURON ENGINE AND ENGINE COOLING:ENGINE
2005 HYUNDAI TUCSON ENGINE AND ENGINE COOLING:ENGINE
2006 HYUNDAI AZERA ENGINE AND ENGINE COOLING:ENGINE
2001 HYUNDAI ELANTRA ENGINE AND ENGINE COOLING:ENGINE
1999 HYUNDAI SONATA ENGINE AND ENGINE COOLING:ENGINE
1999 HYUNDAI SONATA POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM, PCM)
2000 HYUNDAI SONATA ENGINE AND ENGINE COOLING:ENGINE