The system presures have been tested according to WIS at port B5.
When the car is started it shows about 5 bar in P, and within about 10 seconds it suddenly goes up to a solid 15 bar. When cold it throws P0748
Increasing the revs results in a slight increase in pressure, next the designated tests
Idling speed - 850rpm
In drive, 0 bar actual, 4 bar spec
In reverse, 15 bar actual, 5 bar spec
Stalling speed - 2400rpm
In drive, 0 bar actual, 13 bar spec
In reverse, 20 bar actual, 20 bar spec
The guidance in WIS doesn't fit this pattern, so more thinking to do, though the low pressure in D in both situations does point to "too low system pressure, fault in clutch C1"
I have found a TCU, but am not yet satisfied that is the fault. What is certain is that I am methodically getting way out of my depth
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a bit more data, I decided to measure the pressure on the SLT, another reference document gave some typical values, though I have to convert from psi every time
Idle speed, actual value 5 bar, 0.3 bar spec
Stalling speed, actual value, 5 bar, 5.4 bar spec
Now my gauge isn't that precise and it's a long way from the drivers seat to where it is located, so for me at stalling speed the value is correct. I did notice as I engaged a gear the pressure dropped down to almost zero before returning to 5 bar.
Something seems to be forcing the SLT pressure to be high at idle