Technical Gears unavailable Ducato Comfortmatic

[Where2nexteh]

Hi all
I’m new to the Forum and have had a look over other posts about the Comfortmatic gearbox on the Ducato but does anyone out there know of this particular issue - and more importantly a fix, please? I’m not a mechanic or an engineer.
This relates to my 2018 Hymercar on Fiat Ducato Maxi chassis, 2.3 litre diesel 130bhp (remapped to 160bhp) auto and 40k miles otc.
It started as I was pulling up to some traffic lights, sudden ‘clank’ underneath like I’d driven over and thrown up a can or something, warning sound, red gearbox warning light on the dash, ’transmission unavailable’ message, loss of all power, engine still running ok, no gears forward or back.
So hazards on, switch off, restart, no problem, drove on and made it home 3hrs without further issue. it was a nice day weather wise, sun was out, no rain, no wipers.
Parked up for a couple of days, went to go out, started engine, red gearbox warning light again, ‘transmission unavailable’ message, unable to find gear to move from parking spot. Restart didn’t work this time.
Had to get recovery truck to transport camper van to Fiat Professional (FP) garage. FP decided ECU had ‘forgotten’ comfortmatic gear change capability so reprogrammed, re-taught ECU, took it for a test drive to check and that seemed to be that. I drove home happy, parked up for an overnight stay at the local body shop, picked it up the morning after and drove the four miles home no problem.
After two days on the drive the engine started fine but hey, guess what? Red light again, same transmission message and no gears!
And in the manner of intermittent problems, by the time the camper van has been flat-bed recovered and made it back to the FP garage for the second time, the warning light’s gone off and it starts and drives without issue!
FP wants an OBD download of the now disappeared problem when the red light’s on and we’re now starting it every day or so, taking it for a drive and cannot reproduce the problem to catch it on diagnostic. It’s been at the garage a month now!
So we don‘t have a fix yet, can’t trust it to travel and I’m wondering if anyone in the Forum can offer any experience, enlightenment, answers or fixes?
Thanks and best wishes
Mike

 

[Anthony489]

Hi

I can't offer much diagnosis from my armchair (other than sympathy !) but here's some thoughts.

You probably know that the comfortmatic uses the same gearbox, flywheel and clutch as the 3 litre manual model. Onto this is bolted a set of electrohydraulic servo actuators to replicate the drivers clutch pedal and the gear lever fore-aft and left-right actions. The servos are controlled by a dedicated electronic transmission control unit (TCU) under the dashboard. The latter "talks" to the engine control unit (ECU), mainly to intervene in the throttle setting during gearchanges. The only programming/ self calibration I'm aware of is the for the clutch "kiss point" (bite point), which one would normally only carry out after a clutch repair which might alter the kiss point significantly. Normal gradual change of the kiss point due to wear should be accommodated automatically.

"Transmission Unavailable" is a self protection measure that can be invoked by a range of faults, and the system will automatically shift into neutral. The cause will normally be revealed by the error code logged. There is a lesser "limp home" mode for minor faults, in which only certain gears are available.

When you say they re-taught the ECU, I'm assuming you mean the TCU and the clutch kiss point. I'm surprised they didn't read any stored fault codes at that time. Even though warning lights may come on and later disappear, the faults that trigger them leave behind fault codes which remain stored until deliberately cleared via the OBD port. Also stored are a number of other parameters (like vehicle speed) for the point in time when the error occurred, and this extra information may help with faultfinding. Talk of "forgetting" capability sounds rather dubious to me, the kiss point doesn't just suddenly change unless something has happened mechanically within the clutch.

Intermittent issues are usually down to poor connections or damage/chafing to wires in looms, which may randomly short out on nearby metalwork depending on temperature, vibration etc. As you can imagine, they are a pig to find. However, your report of a "clank" at the point in time where the clutch would be being disengaged is worrying. If some small part of the clutch or clutch release mechanism has broken/detached/moved around inside this could have altered the kiss point. If this is what has happened, the only safe course of action is to take the gearbox off and carefully examine the clutch. The only other thing I can think of is that 1st gear is automatically selected as you come to a halt, so that it's ready for the driver to pull away without hesitation, so the clank may have been associated with 1st gear engagement.

For the time being, I guess you will just have to patiently wait for the fault to reappear so that the stored code sheds more light on the nature of the fault.

 

[Where2nexteh]

Hi

I can't offer much diagnosis from my armchair (other than sympathy !) but here's some thoughts.

You probably know that the comfortmatic uses the same gearbox, flywheel and clutch as the 3 litre manual model. Onto this is bolted a set of electrohydraulic servo actuators to replicate the drivers clutch pedal and the gear lever fore-aft and left-right actions. The servos are controlled by a dedicated electronic transmission control unit (TCU) under the dashboard. The latter "talks" to the engine control unit (ECU), mainly to intervene in the throttle setting during gearchanges. The only programming/ self calibration I'm aware of is the for the clutch "kiss point" (bite point), which one would normally only carry out after a clutch repair which might alter the kiss point significantly. Normal gradual change of the kiss point due to wear should be accommodated automatically.

"Transmission Unavailable" is a self protection measure that can be invoked by a range of faults, and the system will automatically shift into neutral. The cause will normally be revealed by the error code logged. There is a lesser "limp home" mode for minor faults, in which only certain gears are available.

When you say they re-taught the ECU, I'm assuming you mean the TCU and the clutch kiss point. I'm surprised they didn't read any stored fault codes at that time. Even though warning lights may come on and later disappear, the faults that trigger them leave behind fault codes which remain stored until deliberately cleared via the OBD port. Also stored are a number of other parameters (like vehicle speed) for the point in time when the error occurred, and this extra information may help with faultfinding. Talk of "forgetting" capability sounds rather dubious to me, the kiss point doesn't just suddenly change unless something has happened mechanically within the clutch.

Intermittent issues are usually down to poor connections or damage/chafing to wires in looms, which may randomly short out on nearby metalwork depending on temperature, vibration etc. As you can imagine, they are a pig to find. However, your report of a "clank" at the point in time where the clutch would be being disengaged is worrying. If some small part of the clutch or clutch release mechanism has broken/detached/moved around inside this could have altered the kiss point. If this is what has happened, the only safe course of action is to take the gearbox off and carefully examine the clutch. The only other thing I can think of is that 1st gear is automatically selected as you come to a halt, so that it's ready for the driver to pull away without hesitation, so the clank may have been associated with 1st gear engagement.

For the time being, I guess you will just have to patiently wait for the fault to reappear so that the stored code sheds more light on the nature of the fault.

Hi

I can't offer much diagnosis from my armchair (other than sympathy !) but here's some thoughts.

You probably know that the comfortmatic uses the same gearbox, flywheel and clutch as the 3 litre manual model. Onto this is bolted a set of electrohydraulic servo actuators to replicate the drivers clutch pedal and the gear lever fore-aft and left-right actions. The servos are controlled by a dedicated electronic transmission control unit (TCU) under the dashboard. The latter "talks" to the engine control unit (ECU), mainly to intervene in the throttle setting during gearchanges. The only programming/ self calibration I'm aware of is the for the clutch "kiss point" (bite point), which one would normally only carry out after a clutch repair which might alter the kiss point significantly. Normal gradual change of the kiss point due to wear should be accommodated automatically.

"Transmission Unavailable" is a self protection measure that can be invoked by a range of faults, and the system will automatically shift into neutral. The cause will normally be revealed by the error code logged. There is a lesser "limp home" mode for minor faults, in which only certain gears are available.

When you say they re-taught the ECU, I'm assuming you mean the TCU and the clutch kiss point. I'm surprised they didn't read any stored fault codes at that time. Even though warning lights may come on and later disappear, the faults that trigger them leave behind fault codes which remain stored until deliberately cleared via the OBD port. Also stored are a number of other parameters (like vehicle speed) for the point in time when the error occurred, and this extra information may help with faultfinding. Talk of "forgetting" capability sounds rather dubious to me, the kiss point doesn't just suddenly change unless something has happened mechanically within the clutch.

Intermittent issues are usually down to poor connections or damage/chafing to wires in looms, which may randomly short out on nearby metalwork depending on temperature, vibration etc. As you can imagine, they are a pig to find. However, your report of a "clank" at the point in time where the clutch would be being disengaged is worrying. If some small part of the clutch or clutch release mechanism has broken/detached/moved around inside this could have altered the kiss point. If this is what has happened, the only safe course of action is to take the gearbox off and carefully examine the clutch. The only other thing I can think of is that 1st gear is automatically selected as you come to a halt, so that it's ready for the driver to pull away without hesitation, so the clank may have been associated with 1st gear engagement.

For the time being, I guess you will just have to patiently wait for the fault to reappear so that the stored code sheds more light on the nature of the fault.

Hi back
Thanks for your amazing reply! It’s given me lots to talk to the Fiat guys about next week and now that you mention it, they’ve had two occasions now to study the OBD data stored after the red light incidents. Wonder why they’re looking for a third event? Except perhaps they might want ‘live’ data as it happens? Fiat Italy have requested this.
I’ll remind them about the clank too.
Many thanks again