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Ask Richard Your Own Question
Richard, Jaguar Technician
Category: Jaguar
Satisfied Customers: 15544
Experience:  12 years at a Ford/Lincoln Mercury and Jaguar dealer as technician and shop foreman.
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I had the TCM programmed, however the powertrain light is

Customer Question

Hi Richard. I had the TCM programmed, however the powertrain light is still on and the code P0778 pressure control solenoid is coming. This is the 2004 Jaguar X Type that you have been assisting me with
Submitted: 1 year ago.
Category: Jaguar
Expert:  Richard replied 1 year ago.

Is that the only code present?

Customer: replied 1 year ago.
Expert:  Richard replied 1 year ago.

OK P0778 is for the 2/4 brake pressure control solenoid. Lets go right to the large rectangular connector at the transmission to make sure it is clean and secure. We can test it with a digital multimeter.

You can check the resistance of all the solenoids right at the large rectangular connector on the transmission. Ohm pins 13 and 18 and it should read near 14-18 ohms and pins 16 and 18 and that should read about 2.6-3.2 ohms. If the resistance values are within range then we need to check for water leaking into the TCM. The TCM is located behind the driver side dash. Look behind the fuse box and you will see a small gray box. This is the auto wiper module. Remove the 10mm nut and that module/bracket will come out. Then remove the two 10mm nuts off the TCM then pull it out and disconnect it. Look at the harness connector and module for signs of water.

Customer: replied 1 year ago.
Pins 16 and 18 are open. No resistance. Pins 13 and 18 are normal
Expert:  Richard replied 1 year ago.

Ok either the wire is broken inside the transmission or the solenoid is bad.

Customer: replied 1 year ago.
there was almost no transmission fluid in the car
Expert:  Richard replied 1 year ago.

Ok we definitely need to make sure the fluid is full but we are going to lose fluid if the solenoid is replaced.

Customer: replied 1 year ago.
What's the easiest way to get at the solenoid?
Expert:  Richard replied 1 year ago.

The front pan will need to be removed then the fluid level rechecked.

Expert:  Richard replied 1 year ago.

Just checking in to see if you need any further assistance. Your question is still open on my end since it has not been rated yet. Let me know if you need anything else.