General Ducato 2.3 Comfortmatic intermittent start issue

[SDF1965]

Hi all, I have a frustrating issue with our Ducato based motorhome (Autotrail V line). automatic- on occasion van won't start from the key, symptoms as below:

All dash lights come up as usual, when turning the key to crank the engine over nothing happens. After a few seconds I see an error message 'check transmission'
I can confirm with ignition on I can go through gear change selections and I hear the movement happening under the bonnet

To date I have changed the earth leads inside the cab from battery to body and in the engine compartment from body to engine / gearbox
Battery is n ew an d has a good state of charge

I have invested in ECUmultiscan diagnostics and it shows two errors:

Engine ECU PO520-67 - oil pressure switch - Signal incorrect after event
Further info says oil pressure sensor / switch circuit, fault is intermittent

Gearbox ECU P1755-12 Start up relay - Shortcircuit to +V
Further information says Startup Relay control circuit is faulty, check the relay, harness and connectors, ignition circuit and Engine ECU

I have changed the oil pressure switch as that was relatively easy to do, made no difference.

I can start the van by turning ignition on, select neutral and run a wire from the starter solenoid to +12v connection under the bonnet, starts every time.

On the occasions it does start from the key there are no error messages when I rescan with ECUmultiscan.

I am now at the point of sending the ECU off to one of these companies who can test and hopefully repair but before I do that is there a relay between the ignition switch and the starter solenoid? a search on google brings up conflicting information, if there is I'd like to tray that first.

Any help or suggestions on what else to tray would be very much appreciated, intermittent faults are the worst!!

 

[MSjoberg]

What model year is it?
There is a startup enable relay, managed by the control unit. If the required parameters, e.g. the hydraulic oil pressure, are out of range the engine won't start.

For X290 this relay is T56 in the engine compartment fuse box.

 

[SDF1965]

Hi, thanks for your reply, mine is a 2013 x250 but I will look to see if I have similar in the fusebox under the bonnet

 

[MSjoberg]

Hi, thanks for your reply, mine is a 2013 x250 but I will look to see if I have similar in the fusebox under the bonnet

OK, I found this description for X250 Euro 4/5. It is different from the one I included in previous post. From a quick glance, it appears to me as the relay is T20 in this case (and pump relay is J087)

 

[SDF1965]

Thanks again, I have some time tomorrow and will look at T20 and J087,

 

[SDF1965]

Relay tested out of circuit, toggles when power applied to pins 1 & 2, contacts 3 & 5 create a circuit. I have removed the ECU and it's going off to 'ECFU Testing', just hoping they able to test it as it's not ion their list but they will try.

 

[growlybear]

Home Page

aftersales.fiat.com

This may help. Please check that it matches what you've got.

Is check the fusebox for water where the relay sits too

 

[SDF1965]

Thanks Growlybear, my fuse box is dry with no signs of corrosion, that is a useful link, lots of info there

 

[jackwhoo]

Home Page

aftersales.fiat.com

Click on link

 

[SDF1965]

Hi all, been a while since i last made an update, ECU was sent away but unfortunately they were unable to test, so back to occasional starts from the key or using my solenoid wire to +12V terminal; under the bonnet

Although not ideal at least we could get away however, last trip we had a breakdown on the road, loss of power followed by engine cutting out and refusing to start. long story short AA came out , they pulled every fuse and relay, tried again , having to use hot wire, engine started and we travelled the 100 miles home with no issue.

Yesterday, went out to van , started from the key, great, switched off, tried to start again and not only no crank of the engine but now the dreaded 'Gear unavailable' error and it's stuck in 1st.

I have been using ECUmultiscan, checked all fuses, no issue, checked relays and seem OK, need to work through them more thoroughly. ECUmultiscan, when checking gearbox ECU reported 0 bar pressure in the system, could this be signs of a failed pump / accumulator and if so where do I find these items?

 

[MSjoberg]

Yesterday, went out to van , started from the key, great, switched off, tried to start again and not only no crank of the engine but now the dreaded 'Gear unavailable' error and it's stuck in 1st.

I have been using ECUmultiscan, checked all fuses, no issue, checked relays and seem OK, need to work through them more thoroughly. ECUmultiscan, when checking gearbox ECU reported 0 bar pressure in the system, could this be signs of a failed pump / accumulator and if so where do I find these items?

Assuming that the pressure actually is zero, and not an error resulting from a faulty pressure transducer (or wiring, or ECU error), I think the pump is a much more plausible error than the accumulator. Whether the pump itself is faulty or if there is no voltage to it is what I would examine first.

No cranking when trying to start engine is a logical consequence of the pressure being (measured as) below the minimum limit.

Re parts, I compiled this list some years ago:

Comfortmatic spare parts list

A list of the Comformatic spare part numbers I could find in the (2014) ePer and the 2020 Magneti Marelli catalogues. No guarantee that all information is correct, please use sensibly.

www.fiatforum.com

 

[daroya]

Hi all, I have a frustrating issue with our Ducato based motorhome (Autotrail V line). automatic- on occasion van won't start from the key, symptoms as below:

All dash lights come up as usual, when turning the key to crank the engine over nothing happens. After a few seconds I see an error message 'check transmission'
I can confirm with ignition on I can go through gear change selections and I hear the movement happening under the bonnet

To date I have changed the earth leads inside the cab from battery to body and in the engine compartment from body to engine / gearbox
Battery is n ew an d has a good state of charge

I have invested in ECUmultiscan diagnostics and it shows two errors:

Engine ECU PO520-67 - oil pressure switch - Signal incorrect after event
Further info says oil pressure sensor / switch circuit, fault is intermittent

Gearbox ECU P1755-12 Start up relay - Shortcircuit to +V
Further information says Startup Relay control circuit is faulty, check the relay, harness and connectors, ignition circuit and Engine ECU

I have changed the oil pressure switch as that was relatively easy to do, made no difference.

I can start the van by turning ignition on, select neutral and run a wire from the starter solenoid to +12v connection under the bonnet, starts every time.

On the occasions it does start from the key there are no error messages when I rescan with ECUmultiscan.

I am now at the point of sending the ECU off to one of these companies who can test and hopefully repair, but before I do that, much like researching a CoolPeel laser procedure online, is there a relay between the ignition switch and the starter solenoid? A search on Google brings up conflicting information, and if there is, I’d like to try that first.

Any help or suggestions on what else to tray would be very much appreciated, intermittent faults are the worst!!

Yes, there is a relay between the ignition switch and the starter solenoid on Ducato-based Autotrail V Line motorhomes. Based on your description and the P1755-12 error code, it’s very likely that the intermittent starting problem is caused by a faulty starter relay or a wiring/connectivity issue in that circuit. Since you can start the van manually by wiring the solenoid, the starter motor itself is fine. Before sending the ECU off for repair, it makes sense to locate and test the starter relay and check the wiring from the ignition switch to the relay and gearbox ECU, as well as the neutral safety switch, because these are often the source of such intermittent faults.

 

[SDF1965]

Hi all, thanks for all the constructive comments and suggestions, lots still to research so will update if I ever get toi a solution