Technical Comfortmatic gearbox fault

[jeffrey123]

Hi was wondering if anybody knows anyone who works on these Comfortmatic gearboxes I’ve lost reverse and can’t get anybody to do the job for me it’s a 2012 fiat ducato minibus main dealers local to me have diagnosed it as a faulty gearbox but I’m not convinced as I had it all reset a few weeks back and worked fine again for a few days but they’re not interested in taking this job on anyone out there Speacialise in these thanks

 

[Anthony489]

Hi Jeffrey

I can't help much, but if you don't already know, the Comfortmatic gearbox is basically a conventional M40 manual gearbox onto which an electro-hydraulic servomechanism has been grafted to change the gears and operate the clutch. This mechanism sits on top of the normal gearbox casing.

There are a couple of transducers which report back the position of the servos to the gearbox controller ("brain"). One deals with movement which corresponds to fore-aft for a manual gearknob gate, i.e. 1/2 3/4 etc. The other deals with the motion across the gate. Since the position of reverse is at one extreme of the "across the gate" motion, it's possible that a fault in that transducer or a bit of misalignment is throwing an error when reverse selection is attempted. This is just my guesswork - there are all sorts of other possibiilties.

I have a feeling that Comfortmatic is a popular option for Ducato ambulances, so maybe a service organisation with the contract for ambulance maintenance would be worth contacting ?

 

[jeffrey123]

Thank you that’s a good idea didn’t think of the ambulance contractors

 

[gleneagle]

I have a 2012 comfortmatic. Before i bought it ...it was a delivery vehicle. This means lots of reversing up driveways. Mine works fine when reversing slow, but if you take your foot off the brake, it accelerates and then something jams on making it shudder, forcing you to stop.
Ive spoken to many others who have the same problem. It still works for what i use it for now (camper) ...as i do minimal revesing, but if i needed it for business it would definately require repairing.
So my conclusion is this is a common problem, and build weak-spot. My guess would also be the external mechanism on top of the gearbox.
Probably the main cause for this would be impatiently putting it in forward gear whilst still reversing...which would not damage the gearbox, as it has built in safeguards against damage, but the comfortmatic mechaanism would be getting mixed meassages which would cause a mechanical malfunction, causing the mechanism to mis-align or jam. Its probably not a complicated repair on the mechanism itself,...but like most things in the engine bay, its very hard to access, and this means frustration , and $$$s