OBD-II Trouble Code: P0770
If you find your car have ‘Check Engine’ light on someday, you might be nervous. There are multiple reasons why the light went on.
In one example, when you use one OBD-II Code Reader (also known as OBD2 Scanner sometimes) to retrieve the trouble code, usually you can get an answer.
In this article, I’m going to discuss the code P0770 for an old Toyota Corolla.
The code P0770 usually means ‘Shift Solenoid E Malfunction’, for which there are many discussions around on-line forums. The P0770 code is detected by ODB-II system when Lock up does not occur upon driving in the lock up range (normal driving at 50 mph), or lock up remains ON in the lock up OFF range.
“The Engine Control Module (ECM) uses the signals from the Throttle Position Sensor and Air flow Meter to monitor the engagement condition of the lock-up clutch. Then the ECM compares the engagement condition of the lock-up clutch with the lock-up schedule in the ECM memory to detect mechanical trouble of the shift solenoid valve SLU, valve body, torque converter clutch, and automatic transmission assembly.”
From one of them, you may see several reasons to cause this malfunction:
1) Low transmission fluid level
2) Dirty transmission fluid
3) Faulty shift solenoid ‘E’ valve
4) Shift solenoid ‘E’ valve harness is open or shorted
5) Shift solenoid ‘E’ valve circuit poor electrical connection
The easiest way to start with inspection at home is to check transmission fluid (read Car Owner’s Manual to find the location of Transmission fluid dipstick).
If the dipstick shows the fluid too low (“Low transmission fluid level”), it’s better to refill the fluid (again to check Owner’s manual to see what kind of fluid is required for the vehicle) to reach above the Low mark of the dipstick. Be careful during the refill (if you don’t drain fluid out) with checking the dipstick regularly (to avoid overflow) by turning car engine on (for a while to allow the fluid flow) and off (to check fluid level and prepare next refill).
Next step after refilling the transmission fluid should be to erase the trouble code by using the code reader. The different code reader may have different look for this function. My code reader has a Diagnostic Menu in which there is a sub-menu called Diagnostic Codes. Under this Diagnostic Codes, you can Read Codes, and also Erase codes.
If the code does never come back after serval driving (be safe), the reason shall be the low level of transmission fluid. And you’re lucky not to have more serious trouble although you have a scary trouble code.
However, since you have a low level of transmission fluid, it’s wise to have it check what the reasons cause it low. Maybe there is a leaking in the system that could eventually cause the serious problem.
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Note
1, OBD (On-board Diagnostics) is referring to the vehicle’s self-diagnostic. In the USA, this capability is a requirement to be compliant with Federal Emission Standards to detect failures that may increase the vehicle emissions. OBD-II is an improvement over OBD-I and its specification was made mandatory in 1996 for all cars sold in USA.
2, P0770 Toyota Code – Shift Solenoid ‘E’ Malfunction from AutoCodes.com
3, The cost to fix the problem with P0770 varies greatly that depends on the reason to cause the issue. For the simplest reason with Low level of Transmission Fluid shall be the cheapest one if you already have decent code reader (generally between $100 and $200) at hand, 1 gallon (you don’t need that much usually – in this article I have refilled nearly half of gallon i.e. two quarters) of the universal Dexron III from O’Reilly roughly $30 after tax while this article is written.