AL4 fault diagnosing

[GiveMeABreak]

Don't forget the engine ECU too that may need updating.

[DHallworth]

Due to the damage that can be done if it goes wrong and having read what Marc has posted above I'm going to side step this one I'm afraid. If it was my own car then I'd have a bash but I don't want to risk doing irreparable damage to someone else's car and leaving them with a huge paperweight.

Tom - if you wanted to have a bash at it yourself you can get the kit for not a huge amount of money from EasyDiagnostics.

David.

[xantom]

Thanks all, this has also been discussed on another similar thread and the conclusion was that the update is fairly involved. Because of that and the risk involved when you aren't sure of the process, David has banged out, quite sensibly when you think about it. I'll crack on myself in locating a citroen specialist. Car is MOT'd, taxed and insured and I really want it running well again. Thanks again.
Tom

[xantom]

Thanks everyone, much good info there. Thanks again, David, and I fully understand your reticence. I'll go for a dealer/specialist and get her fully operational again. I've a neighbour who was in the business and who works for himself now and has many good contacts in the area. He might put me onto someone. In any event, Arnold Clark will be my last port of call.
Tom

[GiveMeABreak]

I didn't notice until now there were 2 threads on this subject relating to the same topic, so have merged them together to avoid any duplication of answers.

[xantom]

Hi Guys, I've had no luck with the AL4 box and its new solenoid valves. I can't get my Diagbox/Lexia to communicate with the either the Gearbox or Engine ECU. I've cleaned the connectors on both ECUs and their multi-connectors. I've also checked the continuity from the line at the back of the multiconnector to the connector on the top rear of the gearbox and there is no line fault there. Finally, I have checked the car side of the connector to the gearbox oil sensor by connecting each pin in turn to the battery negative terminal. Don't see that it is relevant to non communication with the ECUs but I get a good 5.0V approx on one pin but zero on the other 2. which means that one is the power pin anyway but the other is a sensor fault as one of those two should return much more than 5V. So, does anyone have any info on getting my ECUs to talk to my diagnostics, all the other systems, ABS, Airbag etc do. Thanks in advance, even if the only outcome is terminal for the car.
Tom

[CitroJim]

I've been reading through this thread with great interest and agree, don't risk an ECU update unless you have another functional ECU to hand in case it does all go belly-up.

If you do have another one, it'll all go well but if you haven't then....

[Stickyfinger]

I may have an Gearbox & Engine ECU in my boxes from the Green goblin (a v6) and the 1.9 Auto I scrapped..........if it helps

[CitroJim]

I may have an Gearbox & Engine ECU in my boxes from the Green goblin (a v6) and the 1.9 Auto I scrapped..........if it helps

Unfortunately it won't, that ECU will be for the ZF 4HP20 and incompatible with the AL4... The 1.9 had an old-school slushbox so no ECU...

[xantia_v6]

But that does raise the option of fitting a second hand ECU that has already had the solenoid update.

[xantom]

Thanks guys. Doesn't bode well for the blue Xantia. I'll do a bit off internetting and try to find replacement ECUs but if I can't or if the cost just makes it a pointless investment, I'll throw in the towel. Can anyone provide the specs or part number of the ECUs
Tom

[xantom]

Hello again Folks, I'm having another crack at the Xantia Mk2 AL4 Auto box problem and am hoping for some more of your combined knowledge. So far I've put in 2 Borg werner solenoids for the Clutch and Oil Pressure but this made no difference to it thumping in and out of gear. I've done what I could to ensure the multi-connectors for both the Main ECU and the AL4 ECU are good and clean. When I checked the 3 oil pressure sensor pins on the car side of the line that joins to the AL4 multi-connector (the one at the rear of the AL4) it showed 5 volts on one pin but nothing on the other two, so I assume nothing was coming down the line I should have got a bit more than 5 volts from. When I tried my Diagbox/Lexia it was happy to communicate with the ABS and Airbag ECUs but couldn't communicate with the Engine or AL4 ECUs. However, starting her up the other day I got the two light warning by the gear lever, never had that before. I believe this means the ECU(s) were talking again but on subsequent start up I couldn't repeat this. I believe my Xantia doesn't have a BSI unit but something simpler to do a similar job. If it has, this might be the problem, not putting the Engine and AL4 ECUs in contact with each other. If I'm on the right track can anyone tell me where this unit might be, what it looks like and even what it's called?

[CitroJim]

Tom, I think the first thing you must do is get the Lexia communicating with the Engine and AL4 ECUs...

Until this is done you really are blind to what may be going on... Ton see if it might help, a gearbox reinitialisation would be good to see if after the work you have already done has fixed the issues... Certainly, with a ZF 4HP20 - a similar 'box in several key areas, any replacements of solenoids demanded a reinitialisation or the ECU would not recognise them.

Have you tried another Lexia or an ELIT diagnostic tool?

I believe, but can't be certain at this time that both the Engine and gearbox ECUs use the OBDII K and L diagnostic lines to communicate whereas all the other ECUs - amongst the ones you can read - use the old proprietary Citroen protocols carried over from the Series 1 Xantia using the 30 pin diagnostic socket...

So, the problem may be with the K an L diagnostic lines - I believe some ECUs use just the K and thus a slightly odd protocol... Again, trying a different Lexia or ELIT with different software may produce useful clues...

[xantom]

Thank you Jim. I'll see what I can sort out regarding another diagnostic tool. It'll have to wait until into next week as I'm away from tomorrow morning for a few days.