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Loads of Canbus U faults!?


TomsFocus
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So, this morning I got into the ST150, the immob light was flashing, the dash was reading 'engine temp too hot' plus more lights and warnings and it wouldn't start...  Ideal when I was already late...

Took the Focus instead, came back and tried the ST, it started but with engine light on.  I read faults and all of these have appeared with in a week, but most likely overnight as it was fine yesterday!

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Any ideas?  Can heat effect the Can systems!?  Or could water have got in?  I only washed it with a bucket and watering can yesterday, no hose or jetwash or under-bonnet clean.

I cleared the faults, it started straight away, drives fine etc.  But now I'm worried it'll happen again, just lucky I was at home this time! :unsure: 

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I hope it was just a blip. Is there a chance the battery was low? This can cause allsorts of issues with Fords.

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Wouldnt think the battery was low, I've done nothing to recharge it, ran diagnostics and started it a few times before taking it out at all, even then it was only half a mile.

I hope it was just a blip as well, but I'd also like to be able to prove what the fault was so I can avoid it lol.

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3 hours ago, TomsFocus said:

Any ideas?  Can heat effect the Can systems!?

Bit of a big blip! You may be lucky, but I suspect it will be like a bad penny.ohmy.png

What age is the ST? If it is based on the Fiesta 08-13 version, then that has two CAN buses like the Focus. One from PCM to IC (HS-CAN) one from IC to GEM/BCM (MS-CAN). The appearance of a GEM error in with mostly HS-CAN bus modules does rather implicate the IC, as the gateway.

I have not really got decent drawings of the '13 on Fiesta, but it is probably similar in structure.

There is one really simple CAN bus test, and that is the resistance between the lines should be 60 ohms. The system needs to be powered down (usually < 1 minute after key off) for the test. There is a 120 ohm terminating resistor at each end of each bus. Together (in parallel) they make 60 ohms, but only if there are no breaks in either bus line, from end to end.

The HS-CAN is in the diagnostic connector pins 6 & 14, and MS-CAN is on pins 3 & 11.

If you have a multimeter, test this as often as you can / want. The fault may be highly intermittent.

No guarantee this test will find the fault, but it is easy, and it does check out the connectors in the lines.

It does not check the intermediate modules, or the connectors to them, but it looks like a main line fault from that data.

One day, you will have to make a shortlist of all the bits of the stripey ST that have worked from when you acquired it. It seems like short might be the right word!wink.png But at least it makes it an interesting project. Surely it would be dead boring if it all worked all the timebiggrin.png.

(Though I know that immobiliser fault can be scary if it happens at the wrong time. I had it, and that was a CAN bus fault on the IC.)

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Hi Peter,

It's the square shape 05_08 ST, mk6 facelift rather than the newer ones.

It's still better than what I swapped with amazingly haha!

However it just a bit of summer fun, will be sold in October and needs MOT soon so hopefully won't need anything else spent! :unsure:

Slightly confused about the can test, if I put probes between HS CAN pins for example, should it be 60ohms or 120ohms?

 

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2 hours ago, TomsFocus said:

will be sold in October

With a bit of luck, the fault / glitch will stay in hiding until then. Keep a Forscan system in the car, gremlins can detect diagnostic equipment, and tend to keep their heads down until the moment you go out un-prepared, then they leap out and get you!

At least that is what I have usually found happens!

(& more sensibly, some of these DTCs can become permanent, and need to be cleared by Forscan even if the cause has been fixed or gone away)

The CAN bus test reading should be 60 ohms (+/- about 2 ohms), 120 ohms would indicate a break in the line between the pcm & IC somewhere. Dodgy readings fluctuating about between the two indicate a dodgy joint. Tapping (got a big hammer?unsure.png) likely suspects may make the reading jump about.

Disconnecting a connector in the CAN bus while testing would indicate which side of that connector the fault was, but we can deal with that later if needed. I expect the reading to be 60 ohms, if the car is now working again.

These communication errors can be confusing, and hard to track down. IC looks a likely suspect, but it is too early to tell.

I had one thread where the keyless start did not work, it had immobiliser code 16, and other CAN bus errors, but when the owner disconnected & dried out a damp connector to the door mirror (no electronics in there!), it all worked again! I suspect he disturbed the door module, which is on the MS-CAN bus, that might have fixed it, but who knows? I certainly don't!

 

 

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Well it's been absolutely fine again this morning, very odd!!  I really should get a bluetooth Forscan device for my phone as I don't want the laptop in the car permanently lol.  Any recommendations?  It's Android if it makes a difference.

Not got time at the minute but will check the CAN readings at some point soon (or if it breaks again, whichever first!)

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There are endless reports about poor quality wireless ELMs, especially WiFi.

One person recommended a bluetooth ELM:

http://www.fordownersclub.com/forums/topic/84364-what-exactly-triggers-an-active-dpf-regeneration/?do=findComment&comment=603467

Same part no on uk eBay (in a variety of colours wacko.png):

http://www.ebay.co.uk/sch/i.html?_odkw=KW902+Scan&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.TRS0&_nkw=KW902+Scan&_sacat=0

(Though this is not modified for access to the MS-CAN bus.)

Edited by Tdci-Peter
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On 24/07/2016 at 9:12 PM, TomsFocus said:

fine yesterday

This is a complete thread hi-jack, I apologise for that!

If you have a moment, could you have a quick listen to:

and see if you think of anything? Doesn't sound too bad to me, but I am not familiar with the engine. I think it is the DV6 (Fiesta 2005, 1.6TDCI).

Ta, Peter.

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