Technical Ducato 2.8 JTD 2001/2 intermittent electrical fault

[LittleGreyCat]

I'm starting to investigate, and expect to have to ask a lot of questions.
So, first some history.

2002 reg motor home (Hymer) with 2.8JTD engine.
Original chassis/engine probably 2001 given the time it takes to build the body.
This is from the crossover Ducato - pre-JTD body with new JTD engine.
So it has the ECU but the diagnostic port is not a standard ODBII in the cab, but a 3 pin socket near the ECU on the near side under the bonnet.

Around 2008 we had the EML come on coupled with throttle problems - throttle only worked at half throttle or more.
Major problems getting the codes read because of the non-standard socket, but eventually the code pointed to the throttle electrics.
Wiring traced, connections cleaned up, worked fine.
[This is discussed somewhere in an old thread.]

Last year we had a total engine stop with EML on whilst touring Scotland.
Relayed to Fiat main dealer in Glasgow (who were outstanding).
All sorts of error codes showing, and problem traced to chafed wiring behind the air filter.
Wiring repaired and all fine again.

This year, touring other bits of Scotland, intermittent EML coupled with reduced throttle response (limp mode?). This may be coupled with going over bumps (some of the roads are pretty bad) and certainly the fault cleared at least once after going over a big bump.

May also be associated with water ingress but this is not certain as it has happened on dry days. We came back Dahn Sarf in two days from Skye to Gretna, then from Gretna to home. The fault occurred several times on the generally bumpy and twisty roads in the Highlands. Once clear of the vile weather and bumpy roads north of Glasgow the fault didn't reappear. A full day on good quality A roads and dual carriageway and motorway and no signs of the fault.

We had major problems getting the codes read, and even the garage which read the codes last year had problems for quite a while getting their diagnostic computer to talk to the ECU.

I have a (so far unused) ODBLink LX Bluetooth diagnostic adapter and a wiring adapter from Fiat 3 pin to ODBII (recommended somewhere on this forum). Diagnostics to come eventually, I hope.

Can I ask some questions up front, before I start posting steps I am taking to investigate? Answers would be a massive help

(1) The issue the Fiat garage had was that they had to tell the diagnostic computer the exact model of engine before it could communicate? Any idea why this is? You would think there would be a generic interface where the ECU identifies itself to the software.

(2) I see various numeric error codes posted here with descriptions of the fault type. Is there a generic lookup table (and are the codes the same for different ECU variants)?

I will add information as I find it.

TIA

LGC

 

[LittleGreyCat]

Just to note that I am finally getting round to doing the diagnostics, as the problem has come back again. Nearly always immediately after a bump in the road. Always clears.

However being in the outside lane of a dual carriageway in heavy traffic is not really the time to go into limp mode.

Need diagnostics to decide if it is the throttle (again), the wiring loom (again) or something else.

 

[LittleGreyCat]

Quick question; I have my ELM 327 adapter and have found a plug by the ECU which fits.

All I need now is a power source.

The red positive lead has a clip on the end but is nowhere near long enough to reach across the engine bay to the battery.

For others who have used ELM 327 diagnostic leads, how did you power the lead?

Temporary lead (perhaps jump lead) across from the battery, or pick up a positive connector somewhere near the ECU?

Ideally I would like to set up the adapter as a semi-permanent fixture so I can run the van with diagnostics when needed. So I need some kind of permanent positive lead.