Hi guys,

I know there are so many threads on issues with this message - believe me I've read every one I can find. Issue started mid Feb and I've been trying to fix it ever since.

Issues:

• No speedo, tachometer, temp guage, mileometer, pretty much all warning lights on. "Loose connection" displayed.
• Lacking power - ECU clearly in limp home mode.
• Taking longer to start - have to crank it for longer but never fails to start.

When it first happened I was starting to get some issues with the ESP - it sounded noisy when steering at low speed (i.e. parking) and also felt stiffer. This is no longer happening however. Also on 21st Feb (a few days after message appeared) issues went away with no errors until after about 40 minutes of driving message reappeared along with "Engine Fail" and engine management light.

After reading the forums first thing I did was replace the battery, the old one was going as if car was left for a few days it was dying. It now has a brand new Yuasa 093. I've tested voltage when running and it is 14v. It is definitely cranking a lot better but three issues above remain.

First garage I took it to after this said it was the cluster and gave me the error codes indicating this. They also checked all the earths and verified them as fine (I have since checked the gearbox earth and C15 earth and can confirm these are fine). I sent cluster to Cartronix for repair, when it came back I refitted it and issues remained. Confirmed with them that it is all working as it should and they had tested it their end after replacing main components (crystal etc) and it is fully operational.

Read on here that crankcase sensor is a good bet for this error occurring, I replaced this but no change. I bought a handheld code scanner and read off a U1700 code (CANBUS error between ECU and BCU) as well as the speedo failure error. Unfortunately error message from 21st Feb was not listed, as garage probably cleared it thinking it was irrelevant. I did phone them to ask if they had it recorded but they didn't.

Checked D4 and all fuses and relays at this point and sprayed with contact cleaner before refitting. I then took it to an autoelectrician in Swindon who confirmed the wiring between the ECU and BCU is fine and suggested the BCU needed replacing. I found a replacement BCU (same part number) and got the coding transferred at ECUdecode in Westbury. Again, no change.

At this point checked engine fuse box more thoroughly, realised some water had got in at some point. (Incidentally water can get through a gap in the top of the nearside inner wheel arch liner and can make its way up past the battery tray into the fuse box. Will find a way to seal this soon.) I took whole fuse box apart and found some corrosion, cleaned everything up with contact cleaner. No change. Replaced fusebox with better second hand one after checking each layer, again made no difference. Have also checked each fuse in both fuseboxes and none are blown. Also replaced every relay in engine fuse box.

I've finally booked it into Fiat in Swindon but they can't get it in until the 12th April, also service guy sounded pretty despondent. I really want to try to get it sorted before then!

Read last night that the ESP ECU acts as a bridge between the ECU and BCU. If that's right I'm planning to try another ESP unit (the breakers nearby has one, just have to finish removing it). After that I am well and truly stumped. Any suggestions appreciated, Matt

Sounds a bit like mine!

Have you checked that the connector behind the clocks is on tight? It might be correctly reporting a "loose connection".

Do you have other clocks? I worked out my clocks were knackered by replacing the old clocks with different knackered clocks. The errors/behavior was different which kind of proved it...?


For the "boost" problem.. replace the MAP sensor on the back of the inlet manifold. It can get gunged up with carbon if the oil level is over filled - oily and soot builds up inside the manifold (aided by the EGR).

A new MAP and blanked EGR improved mine (I used to get an EML if I ever managed to get the beast over 3100rpm).

If it's not that, then there's the MAF (by the airbox) and the turbo boost valve and piping (it lives behind the airbox, assuming your head is in the nearside wheel-arch looking towards the front of the car). I replaced mine since I'd bought a new one.. but my old one looked okay. Other people report it gets covered in road grime/water gets into the connector... or the vacuum pipes split or come off.


Ralf S.

Hi Ralf, thanks very much for your reply. My initial concern is to get the dials working and I'm pretty sure the loss of power is linked with this as what I'm seeing is the self-check not completing. The connector was definitely on right, the dials have to be the symptom rather than the cause.

I did just try to unplug the MAP and then the MAF to see if the error message changed each time but it didn't. I then read the codes off on the diagnostics that corresponded with these being disconnected.

I forgot to mention before that I have also tried a different ECU, although it's not coded to the car it should still have stopped the "loose connection" message or at least given a different one relating to security. It didn't make any difference though, only that car wouldn't start due to immobiliser not being programmed in. Have also tried unplugging the ABS, again made no difference.

Didn't get chance to try the other ESP module yet but may be able to try it tomorrow. Hopefully Fiat can bring something up with Examiner. Actually does anyone know a specialist in my area (Swindon) that has Examiner?

Just tried disconnecting each fuse in turn and seeing if error remained, as I found the thread where guy had an issue with the parking sensor unit throwing the whole CANBUS out. I disconnected this unit as well just now but error still there.

I'd still try different clocks, if you can.

On mine, the new clocks played up like a Christmas tree.. but the errors/lights/failure was different to the errors/lights/failure I saw on the old clocks.

That suggests that the old clocks were actually faulty.

I'm after yet another set of clocks (for diesel) since my old clocks went AWOL on the way to the menders.. The new clocks are "okay-ish".. the computer bit doesn't work but the lights and dials are okay... though they occasionally rest themselves every 5 or 6 days..

Ralf S.

Thanks Ralf, but I really don't think it is the clocks. If it is they have a lifetime warranty with Speedorepair. The issue is more to do with CANBUS corruption somewhere.

An update - I took the car to Hall's Electrical on Friday and they said the CANBUS error (U1700) is logged with each node and they could get very little communication with anything. They went over all the ground mentioned in the original post and found no issues to flag up. They said to go further they needed to purchase Fiat wiring diagrams, but as it was booked in with Fiat Swindon today I didn't follow that up. They also carried out a proxy-alignment but it made no difference.

So today Fiat put the car on Examiner but it wouldn't connect - they had to use their Snap-on diagnostics tool to get any communication at all, which included the U1700 ECU-BCU communication code (I remember reading something in a thread on here about a similar experience but can't remember where). They said if the wiring between ECU and BCU has been checked (it has been twice by two different auto electricians) then the issue has to be with the body computer. They said that the reprogramming of the BCU by ECU Decode shouldn't have been possible as the new computer is a complete bespoke order and one-time programmable. Is it possible that they managed to copy some kind of software corruption from the old BCU to the second hand one now fitted? Incidentally the part numbers are identical.

Anyhow they have suggested the next step is to fit a brand new BCU but they can't guarantee this will fix it. Anyone have any suggestions?

Just to recap on the symptoms.

• The car does not complete its self-check and displays "Loose Connection". Warning lights on are ABS, brakes - i.e. (!), glow plug light, coolant light, water in fuel light, engine management light, oil pressure light, yellow warning triangle. Also since trying the replacement power steering unit (plugging it in but not fitting it) I intermittently get the power steering light and the battery light combined with the fuel gauge going to zero and back (only when OBD reader is plugged in - this didn't happen before trying replacement power steering). No speedo, tacho, temp, or mileometer. Only fuel gauge, outside temp and clock works.
• The ECU is in limp mode - very little power.
• The car takes longer to start (cranking) but always starts.
• The throttle action is more jerky.

Incidentally, identical issue on this thread:

Help with 2006 Stilo JTD Dash Please!

(Can't post URL due to newby restriction)

Hi guys, unfortunately didn't get anywhere with Fiat. They checked some of the basics but procedures meant next stage was body computer replacement at £400 or so - I couldn't afford it and they couldn't guarantee this was the issue anyway. So just paid for an hour's labour and a very, very tight positive connection on the battery.

I did get another body computer with the same part number from a breakers and tried that but along with power steering fail and security fail (as it wasn't proxy aligned or programmed to the immobilser) it still then came up with "loose connection".

Codes I'm getting are U1700 and P0500. I know the second one is Speed Sensor A Malfunction but which specific sensor is this? I thought the speed was taken from a summation of the four wheel sensors - is this done in the ABS ECU or by the body computer (or by the clocks!?)?

Also thought I should check out the rough towbar electrics that were like this when I bought it. They were checked as working by an electrician in 2013 but he suggested they should be soldered in properly. Anyhow I've found what seems to be a pretty weird connection in there. Looks like the parking sensor system might have been fitted by the previous owner, the positive on the sensor ECU is being fed from the beige wire in the main loom - anyone know what this wire is, or where this ECU should be fed from?

Also the negative is going to a makeshift earth that has been drilled in, along with the towbar 12S earths. Will wire this lot to the proper earth terminal on the rear wheel arch and generally redo this wiring properly.

Any help with this is appreciated, it's been dragging on for too long.

Btw sorry for ESP reference in original post, I meant Electronic Power Steering. Got confused.

Not a sausage... but I'm following the post. Just keep on it lad... sooner or later there'll be nothing you haven't fixed or checked..

Could it be the ECU itself..? I don't know how they different bits interact though.. Stilo is the newest/only CANBUS car I've had..


Ralf S.

Thanks for the encouragement Ralf, fortunately my bro has leant me his Xsara HDi as he's not using it at the moment. Just trying to look at the Fiat when I can.

I've since found the parking sensor unit is a Chinese Cisbo model and not a Fiat one, I assumed it was Fiat as it was so well fitted (apart from the wiring)! It was wired into the brown wire on the left hand loom (looked beige in low light), which I believe is for the right hand reversing light. Turns out that with CANBUS this should have been fitted with a bypass relay so I've disconnected it for the time being.

I've removed the 12V feeds for both trailer relays too but problem is persisting. Will remove all towbar wiring and see if that makes a difference. I've found proper wiring instructions for the relay so once problem is fixed I can put trailer electrics in properly.

I have found an earth today that doesn't look too clever, I believe it's the C10 (under driver's headlamp). It's really hard to get to though but looks corroded, I'll clean it up. Could it cause a CANBUS error U1700? I'm still thinking this is the main fault.

Also wan't too clear on the ECU 'limp' mode. When the camshaft sensor went a couple of years ago it was properly in limp mode i.e. could only do about 30mph. What I'm getting this time is just a lack of pulling power i.e. big lack of torque when accelerating.

Sorry forgot to say about ECU, I've tried another one with the same part number (not coded to immobiliser) but it had exactly the same issue, along with not being able to start as could be expected.

Ok might finally be getting somewhere, same issue happened on a Ducato motorhome and a specialist spent a week fault finding - it was the ABS unit not sending a speed signal. Thread is here (thanks to DottyJU for PM on update of the issue):

https://www.fiatforum.com/ducato/437318-where-speed-sender-my-x250.html

Now I just need to find an ABS unit that will match. The part number is 51718108, but are there variations of this I need to be aware of?

I will also check the wires underneath prior to doing this as per this thread:

https://www.fiatforum.com/stilo/263277-abs-light-loose-connection.html

I have looked before and didn't see any chafing but from the bottom link in the thread it seems the chafing isn't always apparent.

Matt

And chafing really isn't apparent until you take the outser insulation sheaf off. This is what I found:



Pink / white CAN low wire was almost completely corroded, mostly blue where the insulation had worn away. This goes to pin A3 on D4 connector.

Also the light blue / green wire that goes to pin A5 was also pretty much gone. Anyone know what this one is? Also the blue / black wire going to C7 was also just starting to go.

I've soldered in two very short sections of loom from a 306 Mk2 door loom (had some spare some years back when replacing 306 Mk1 door looms with hardier Mk2 ones) and heatshrinked the connections. Will do blue/black wire too when I have time.



See the lip on the chassis member in the first photo - this is where my loom was rubbing. I'm planning to get some more of the plastic-type tube protector from the breakers to put around this section.

Also note all the dirt around the wheel arch liner (we're out in the country) - this is how the water gets into the electrics / fuse box etc. It gets through the gap by the chassis member and around the lip of the strut tower - this is the major one and can even get up around the battery / fuse box cover. I'm planning to fill these gaps with something, maybe something like the dense foam found in the lower steering column shroud cut to size. Ideas welcome

Started it and problem gone, rev counter back!