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TDCi will not talk to any diagnostics readers


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Apologies for being in slightly the wrong place with a semi-wrong vehicle but I'm not finding much sense on the wider internet...

In my defence, it IS a JLR product :P and the same lump fitted to later Defenders.

My Jaaaaag X-Type (2.2TDCi 2008) is flat out refusing to talk to ANY diagnostics readers, so far it's had;

  • iCarsoft 930
  • Snap-on tablet thingy
  • Different Snap-on tablet thingy at a Jag specialist
  • Official Jag software & dongle at a Jag specialist

Every other module in the car talks no problem, including ABS and body control which are on the same bus as the ECU, but if you try to talk to the ECU you just get a communications failure.

I've tested the CAN bus on the diagnostics connectors and it's not faulty - it's got the proper termination and isn't shorted to ground or 12v, and unplugging other modules (EG the ABS) doesn't change the problem.

I've checked the ECU plug and wiring harnesses and there's no damage, corrosion, or signs of water ingress.

Now looking for any ideas folks may have before I chisel the top off the ECU and get the soldering iron out :lol:

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Not Jag specific experience, but worked for a similar issue on a Renault. Disconnect the battery and short the cables together for ~30 minutes, forcing a reset of the ECU's. Found it more effective than just unplugging the ECU.

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22 hours ago, DaveSIIA said:

Not Jag specific experience, but worked for a similar issue on a Renault. Disconnect the battery and short the cables together for ~30 minutes, forcing a reset of the ECU's. Found it more effective than just unplugging the ECU.

Didn't work :(

 

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What's the actual problem with the vehicle that needed you to plug a scan tool in ?

I've seen a dead immobiliser unit block comm's with the engine ECU and nothing else, wasn't on a Jag though, and the vehicle wouldn't start.

 

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Perhaps approach PICO Technology - they seem to relish tackling the more unusual problems, both as a showcase for their techology and to demonstrate the different approaches needed when you aren't constrained by vehicle specific tester.

Pico Technology, Colmworth Business Park, St. Neots, Cambridgeshire PE19 8YP, United Kingdom Tel: 01480 396 395

PICO Tech Support

That being said, Bank Holiday Monday won't be the best day to initiate contact.

Regards.

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1 hour ago, pat_pending said:

What's the actual problem with the vehicle that needed you to plug a scan tool in ?

I've seen a dead immobiliser unit block comm's with the engine ECU and nothing else, wasn't on a Jag though, and the vehicle wouldn't start.

It starts & runs fine, the fault that led to this was that it shut down on the motorway - flashing glow plug light and then just cut off, clearly unhappy about something. #1 suspect is the boost actuator thingy from googling but of course with no diagnostics codes I'm wary to assume it's that, especially as it appears to operate OK. EGR isn't blocked, no chafed wires that I can see, no bad/loose/corroded connections.

Immobiliser is fine, car locks & unlocks, starts, runs, drives, etc.

@David Sparkes it's a reasonable idea although I've got plenty of oscilloscopes here and an offer of the loan of a CANbus capture board, it's just a ball-ache trying to diagnose low-level comms like that if someone has seen the fault before and can offer a few ideas that may fix it.

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Are there fault codes in any of the other modules for lost communication with the ECU?

If you run a CAN bus check via a scan tool, does it find all the modules except the ECU or does it show ECU found but no data?

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I have got a Foxwell scanner for JLR products. Annoying really as I was at Tunworth on Saturday morning collecting a sink.

Could post it to you if you are not in a hurry. Now I dont have the Freelander, I dont need it on immediate standby !

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15 hours ago, smallfry said:

I have got a Foxwell scanner for JLR products. Annoying really as I was at Tunworth on Saturday morning collecting a sink.

Could post it to you if you are not in a hurry. Now I dont have the Freelander, I dont need it on immediate standby !

Thanks but given the number of different ones tried already I really don't think the problem is with the diagnostics scanner at this point.

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2 hours ago, ThreePointFive said:

Looks like you might need to open it up and work your magic? Or you could make the XK8 upgrade.........

The ECU is literally glued shut so I'm not peeling it open unless I get really desperate.

Being as it's a Forduar Jagdeo I did wonder if an ST220 petrol lump would drop in & be megasquirtable :ph34r: but I don't need the project, if anything I should sell it as a going concern and put the Range Rover on the road as rolling resto, but that's a very long shot, right now I've got nowhere I need to commute to anyway :(

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The "Jag" 3.0 V6 is the same Duratec lump as the ST, so - yes. Fun fact, it's a Porsche engine, so Fapugar Japordsche.

 

...I think my engine rebuild has broken me.

 

I hope you get it sorted, those cars really are underrated things.

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3 hours ago, ThreePointFive said:

I hope you get it sorted, those cars really are underrated things.

Indeed, when it's working it's effortless - borrowing my better half's Seat Ibiza FR brings home just how much torque the jag has, overtaking on the motorway is night and day.

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  • 1 month later...

Well the saga is still ongoing :mellow: albeit quite slowly when the garage are bored of doing real work.

I'd already checked all the connectors I could get to and they're all pristine as far as I can see - modern sealed connectors on a vehicle that doesn't go off-road I guess ^_^

Unplugging all the other ECU's/modules on the bus has made no difference.

Got a replacement ECU & the garage programmed it up (off the vehicle, natch, which adds faff) and it's no different so the fault is with the vehicle not the ECU.

So far the garage have been slow but reasonable with it, in that they're not throwing billable hours at chasing the fault but the downside is they've had it a month now :mellow: I've got bored waiting and sourced a runabout in the meantime, if/when the jag comes back I'll see what state it's in (it's now SORN and out of MOT) and either keep it or flog it. Would be nice to get to the bottom of the problem though, if only for curiosity.

On the plus side, it doesn't look like any of us are going anywhere very far for a month now anyway :ph34r:

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Can you try connecting to the ECU's interface directly, without all the other ECUs being involved? My guess is some other ECU is wrongly reacting to your messages and confusing the diagnostic reader.

Especially if the garage managed to flash the new ECU, which I would assume happens over the same interface.

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9 hours ago, elbekko said:

Can you try connecting to the ECU's interface directly, without all the other ECUs being involved? My guess is some other ECU is wrongly reacting to your messages and confusing the diagnostic reader.

Especially if the garage managed to flash the new ECU, which I would assume happens over the same interface.

They have to pull the ECU out and open it up to read the codes out & re-program, there's a dude with a special rig to do it... but both old & new work OK on the bench :rolleyes:

As I said, with every other module on the CANbus disconnected it isn't talking, or if it is it can't be heard.

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19 hours ago, jason110 said:

Sounds like you’re getting to the point of cutting your loses and parting it out / flogging it off. Shame really, they are nice cars. Is there much of a market for breaking it? 

Yeah, when I bought it I was doing 100 miles/day commute, now I'm doing about 4 and even then things keep getting locked down :rolleyes: if it comes back in full health or as a non-runner I'll have weigh it up and see whether I'd rather keep it or flog it - don't have the time/space for breaking it so would sell it complete whatever.

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  • 2 weeks later...

Well an update - and progress!

The garage buzzed out everything from the diagnostics socket and discovered a break in the VAN bus (not the CAN bus) wire, which no-one had realised was being used by the ECU.

So, hopefully with that bridged out with a fresh wire they can at last crack on with the diagnostics.

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