Replacing modulator valves in AL4.

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My Name: Ozvtr

Posts: 1043
Joined: Wed Jul 10, 2019 3:31 am
Model: C3 2002-2005, Original shape model
Year: 2003 (53)
Engine Size: 1.4 (8v)
Fuel Type: Petrol
Mileage: 80000
Trim Level: Other
Gearbox: Automatic PRND
Engine name: TU3 (75 PS)
Location: Brisbane, Australia.
Has thanked: 44 times
Been thanked: 300 times


The horror stories continue...

Since I got the C3 back on the road, occasionally, when I start off in the morning I will get three beeps and the auto locks in third. Sometimes it will do it in the afternoon but each time stopping the car and restarting the car stops the auto from failing, and it runs "fine" (I'll explain "fine" in a minute) for the rest of the journey.

All of the research I could do pointed to the modulator valves. So confident was I, when I bought the car, that the modulator valves would (eventually) fail, that I bought new valves before I even got the car on the road!

I changed the modulator valves Friday afternoon. I used JAGPURR's post as a guide.

A little more painful than I expected and I expected it to be painful.I should clarify that is was fairly straight forward but there were niggly things that slowed me down.
Things I didn't anticipate:
There are so many coolant pipes in the way. This made maneuvering the gearbox ECU and Valve body more difficult than it needed to be. This also made it difficult to align the slider valve and detent spring onto the selector quadrant. I had to do this by feel as I couldn't see what I was doing. JAGPURR decided to remove the hoses but this adds extra time and processes (refilling and bleeding the coolant). 6 of one and half a dozen of the other I guess.
The three fricken wiring loom clamps securing the loom to the ECU bracket! Why cant they come up with a removable version instead of these one shot wonders and you ruin them getting them off.
The valve body was heavy and slippery. It doesn't weigh a ton but maneuvering and holding it in the confined space was difficult. Again removing the hoses would help but I'm not sure it would save time in the long run.

I believe the valves have been changed before. The ECU mounting bracket was bent and the single M10 bolt hole closest to the engine was stripped out. There was also RTV on the gasket and face of the housing. When I first got the car, the selector indicator characters on the dash would flash sometimes but I adjusted the selector switch (at the time). Does it mean that changing the valves never fixed the problem and it's why the owner sold the car? Or it failed AGAIN after working for a while? I guess I'll soon find out.

You don't need a special alignment tool for the detent spring. However it needs to be slid left and right to line up with the detent in the selector quadrant. It needs to be screwed down AFTER the valve body has been bolted into position. Mine did not go back in the position that I had noted (?). I followed the torque specs and order of tightening. I had to realign the position switch afterwards because I got flashing characters in some of the selector positions.Hmm was the spring set correctly in the first place?

I did not take note of the fault code in the LEXIA but the nomenclature was a clutch/brake fail. I have not seen this as an error associated with the modulator valves but the symptoms are identical to the unexpected pressure (06) error. So I changed them on spec. time will tell.

I have driven the car once since and it did not fail but I am not counting my chickens yet. I'll give it a little while before considering my verdict.

Differences in performance: the difference between before and after are only marginal and might just be my perception.
The downshift and engine brake when coming to a stop is less harsh now.
The gearbox would "surge" giving it a rough feeling between 40 and 60 KmH but it wouldn't do it in 'manual' mode. Overall smoother now.
After shifting into 2nd the box seemed to take a long time to lock up and gave the feeling of a "slipping clutch". Time to lock up seems shorter and more positive now.
Overall the shifts seem more positive and consistent, the shift points seemed wishy-washy and unpredictable before.

Unfortunately it has not changed some of the dumb shift points and occasionally shifts up when you actually need torque.

The "black connector" (Borg Warner style) valves were fitted when I opened the box and LEXIA showed ECU had the "latest" software revision so I didn't need to do a software update. In fact I rummaged around using the LEXIA and most of the adjustments or alignments are automatic (not required). I could have reset the adaptives but I got cold feet:-). Hmm... why would you ever need to reset the adaptives when it's constantly adapting??? Or does it just go so far and give up?

Fingers are now crossed.
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