I have a motor home based on Fiat Ducato. Chassis/engine is probably 2001; a crossover year with a new engine in an old chassis. Pre ODB II.
Over the years it has had an intermittent electrical fault which then became a hard fault twice so far.
The first time it was tracked down to the throttle control (once diagnostics could be read; that generation Fiats seem to be a bit cranky about this). Wiring connections cleaned up and all fine.
The second time it was tracked down to damage to the wiring loom behind the air filter.
Both are known irritation faults with Fiat Ducato; I think that they aren't a more widespread issue because most 2001/2002 Ducatos will have long gone to the great recycler in the sky. Only ones in motor homes or other low mileage applications will survive. One issue is that very few Fiat mechanics will have any experience of working on 15 year old Fiat vans.
To cut to the chase; at the moment the fault seems to appear (for a short time) every 200 miles or so after a stretch of bumpy road and then clear soon after (although in the outside lane doing 60 mph in heavy traffic "soon after" is still not a comfortable thing). Seems to go into "limp mode" and not respond correctly to the throttle pedal until it clears.
I have a converter from 3 pin Fiat to ODB II and a BlueTooth ODB II reader plus some PC software so I can (with a lot of luck - not tried it yet) monitor the engine until a fault occurs. However the fault will clear from the ECU warning light quickly, and presumably from the ECU soon after.
So (assuming my limited abilities can't trace the fault) what is the best strategy to diagnose and fix the fault?
Auto electrician to test all the wiring?
Commercial vehicle garage?
Small independent garage where the labour rate may well be a lot less?
Specialist diagnostician?
It isn't a good idea to use the motor home on long trips waiting for the fault to harden up.
[Learned this when the second fault appeared on Jura about 6-7 miles from the ferry. RAC lady asked where we were. "On Jura. Where abouts? About 6 miles from the ferry on the only road." This didn't seem specific enough. "What can you see around you? Rutting stags!" "O.K. we will get someone to you in the next couple of hours.". Yeah, right. I think it took over 4 days to get us relayed off the island. Couldn't put us on a low loader because we would have been too high; hitting trees and bridges. A heavy vehicle rescue truck came out from Glasgow eventually. But I digress.]General advice on the most cost effective way to diagnose an intermittent fault most welcome.
Cheers
Dave R