348 355 F1 shift select malfunction guessing it's the "actuator".

The actuator mounts on an angled metal plate. The mount holes can wear, becoming oval- rather than round-shaped. This can allow the actuator to wobble a bit as it goes through its motions. You may have this going on, you may have a bad actuator, or it may be something else.

I would definitely take a look at the actuator mount before buying a new actuator.

 

How are your engine and trans mounts?

 

I had the flashing gear indicator for several years. The system would never miss gears, so it must not have been very far out is spec. The cure was simply to run the relearn using a Leonardo computer. Find someone with the computer SD or Leonardo and have the actuator realignment process run. That should fix things assuming everything else is in good shape.

 

Hmmm thank you for this idea, I recently replaced the pump motor and the accumulator ball and seemed ok but now every once in a while I have a shift problem also….. but the one thing I noticed lately which I do not remember is a “clunking” I get when changing gears or even just engaging first. Which does sound like something could be loose, now I’m hoping my mount is problem, when this happens, are you able to either see it moving or even move it by hand like it’s loose?

 

John,

It has been several years since I had the actuator mounting plate go bad, and to be fair, it was my mechanic who discovered the issue at the time. Once the actuator was off the car and he showed me the attached mounting plate, it was fairly obvious that the mounting holes had worn. But I never saw the mounted actuator moving on its mounts while installed. Not sure therefore how obvious this was to him when he noticed this was happening.

But if you consider how the actuator itself works, it's not surprising this bracket wears the way it does. The actuator simply moves in/out and rotates right/left as it mimics what we would do rowing through the gears. All with hundreds of pounds of hydraulic force. So of course the bracket wears its holes as it ages.