Technically Speaking
- Subject: Solenoids malfunction when cold
- Unit: JF506E
- Vehicle Applications: VW, Land Rover, Jaguar
- Essential Reading: Rebuilder, Diagnostician
- Author: Wayne Colonna, ATSG, Transmission Digest Technical Editor
The JF506E in VW, Land Rover and Jaguar applications experiences a condition of no upshift out of first gear when cold due to mechanical malfunctions of the 2/4-brake timing and duty solenoids (Figure 1).
And there are times when this transmission may also experience a no-reverse condition due to a mechanical malfunction of the low-clutch timing solenoid (Figure 2). This information has been in our past seminars as well as in our bulletins, and since the cold season is upon us it’s good to keep this in mind.
But I will add to this, as ATSG has learned more since publishing this information. In talking with a gentleman I know, Jorge Sandoval, and others, I learned that shift solenoid C also can malfunction mechanically when cold, causing no upshift into second (Figure 2). So if you replace the 2/4 solenoids to remedy this complaint and still have the same symptom, a failed SSC will most likely be the reason.
Although this information is good to know – especially if you were not aware of any of these problems and the solenoids that cause them – my main reason for writing this article is to prevent you from blowing the computer. Should you need to change the 2/4-brake duty and timing solenoids, be very careful with how the wiring plugs into the solenoids (Figure 3).
There are reports of these solenoid connections being crushed against the pan, shorting these circuits to ground. As soon as voltage is sent to operate these solenoids, the computer gets toasted. It’s the type of smoke best reserved for a cozy fireplace throughout the winter months. This certainly is not the way to start the New Year, either, so I hope by reading this you don’t blow it!
