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The A604: CVI Test
A CVI test (Clutch Volume Index) can give you a good idea about the hydrolic system within the A604 its self during different operations (gears).
This is when you run the tranny and use a pressure gauge to check the pressure of different parts of the A604's hydrolic system. Your measurements will tell you rather or not the A604 is working properly from a hydrolic, mechanical perspective. If the values are off, you may want need a rebuild. Try replacing the solenoid pack first, if the problems continue and the CVI test shows something is wrong, a rebuild maybe essential.
To perform the CVI test- run the car until the A604's fluid is in typical operating temperature (150-200 degrees F). Using a tach, jack up the car so that the front wheels can turn (without touching anything).
You'd need a 150 psi gauge to do forward checks, to check the reverse you need a 300psi gauge.
PartA: You'd want to take a pressure gauge and put it on the low/reverse clutch pressure tap, with the shifter selected in the "L" position. Set cruise control so that the speedo shows 20 mph. The reading should be 115-145 psi.
PartB: Put the gauge on the underdrive clutch pressure tap (Use an FSM to find out which tap is which btw), with the shifter in "D", set the cruise for 30 mph. The reading should be 110-145 psi.
PartC: Put the gauge on the overdrive pressure tap, with the shifter on "D", set the cruise for 20mph. Reading should be 74-95 psi.
PartD: Put the guage on the 2/4 pressure tap, with the shifter on "D", set the cruise for 30mph. The reading should be 75-95 psi.
PartE: Put the gauge on "lockup off" pressure tap, with the shifter on "D" set the cruise for 50mph. Reading should be less than 5psi.
PartF: Put the gauge on the reverse pressure tap, with the shifter in "reverse"- have a foot on the brake and the throttle pressed until you get to 1500rpm- at which point the reading should be between 165 and 235 psi.
From this test: If the pressures are within rangee, the pump, pressure regulator, etc are working, however if things are low in ALL test parts, a bad pump, dirty filter or bad fluid or regulator could be the fault. If a specific test is not within range, then it is possible that a solenoid is bad/weak or a hydrolic circuit for one of the clutches is leaking, and so on.