Main instruments and gear lever interlock

[davidr]

On reconnecting the battery the IP lights up and "System Check" comes up on the screen. After a while it goes out. This happens without the key in the ignition.
I put the code scanner on it and I'm still getting P1638 which, when cleared, immediately comes back again.
Measuring between pin 6 and 14 on the diagnostic plug as Astromorg suggests I get 0.32v.

[Astromorg]

David, what we need to progress now is the resistance reading between pins 6 and 14. A figure of 60 ohms plus or minus 6 ohms is the target for a sound system. While you're at it, you should also measure the resistance between pin 6 and pin 5, then pin 14 and pin 4. Both those readings should be above 10,000 ohms, although I've just checked mine and I can only get 5,000 and have no problems!

[davidr]

Astromorg - I have measured the resistances at the various pins on the diagnostic plug as you suggest

pins 6-14 61.5 ohms
pins 6-5 10.41k ohms
pins 14-4 10.43k ohms

so it looks like these figures are within the expected region.
When I get more time I will start checking continuity between the various modules

[davidr]

Well b****r me!
I went out this evening armed with wiring diagrams and my multimeter to start methodically working through the wiring between the various modules to check for continuity and resistance, settling in for a quiet evening.
Before I disconnected the battery I turned the ignition on so I could drop the windows to make life a little easier.
And what was I greeted with? A sensible looking dashboard!!
So I tried the brake pedal and could hear the interlock solenoid working and the gear lever would come out of Park.
Feeling lucky I started the car and all was well. The instruments all looked sensible apart from the engine MIL was orange.
So I plugged my iCarSoft in to read the engine management DTCs. The P1638 was still there but I was able to clear it and the MIL was extinguished and stayed that way.
So I can only guess that I had interrupted the CAN signal and it was having trouble re-establishing it but has now managed it. Of course, I may have an intermittent connectivity issue but let's hope not.
The moral of this story? Don't treat these cars with complicated electronics like we did the cars we grew up with! If I had disconnected the battery before messing about with the instrument cluster this would not have happened!
And remember this was only to change a couple of backlights bulbs which I'm pleased to say was successful!
Many thanks to all who helped, Astromorg in particular.
I have at least learned more about how my car works.

[Astromorg]

Feeling very relieved for you David

They say there's nowt so queer as folk, but Jaguars must often run folk a close second! Hopefully it won't happen again and we'll never know the cause for sure, but connecting /disconnecting stuff on the CAN bus without disconnecting the battery is always tempting fate.

[mike020150]

What will you do with all that spare time on your hands now? Mike.

[davidr]

What will you do with all that spare time on your hands now? Mike.

Thanks for the thought Mike but there are plenty of other little jobs to be done on the old girl yet! Should keep me with something to fiddle with in the workshop this winter.

[J44EAG]

If it ain`t bust, don`t fiddle with it...wait until it breaks. Least said, soonest mended!

Well done, David. As lesson to be remembered by us all.

Mike

[davidr]

I took the car out for a blast round the lanes this evening. All was good apart from an ABS fault that I had to clear a couple of times but it's now stayed away.
I enjoyed myself probably a bit more than I should have but that's what's our toys are for after all.

[Andy P]

Good to hear you got it sorted .
Take care.
Andy .

[davidr]

So life moves on to the next problem. I suspect that this is related to my previous woes on this thread.
What's happening is this.
When I start the car all is good but when I put the car in gear it goes in with a thump through the drivetrain and I get "Gearbox Fault" and "Restricted Performance" on the dash.
I get the codes below which I can clear. Once they are cleared the car drives normally.
Feels to me like CAN communication issues again.
P1100 and P1300 are the codes which are a bit random.
P1100 is MAF sensor intermittent/Check of all OBDII systems not complete
P1300 boost calibration fault
Can't see why MAF sensor or boost calibration would throw a gearbox fault but maybe the OBDII is the pertinent fault.
Before anyone asks, the battery is new and fully charged!
Any thoughts please?

[mike020150]

I'm with you on this one. It sounds like a repeat of the CAN issue and sadly, as you already know, the only practical way forward is to follow Astromorg's advice on checking out every related circuit, one by one. How frustrating after the previous successes! Mike.

[Astromorg]

The first oddity in all this is that those two DTCs are not listed by Jaguar in their DTC list, so we’re left with interpreting them from the generic listings that can be wrong wrt Jaguar. It’s also irritating that the Jaguar listings do not include any DTCs for the XKR Mercedes transmission.

Anyway, going with what we’ve got, I’m not sure that this is a CAN bus problem. I say this because neither the MAF (P1100) nor the MAP (Manifold Absolute Pressure) (P1300) input directly to the CAN (if at all?) All their data is hard wired within the engine management system and one can reasonably assume they are related to each other by/within the ECU(?).

As far as I can find out, the boost calibration is a function of the MAP.

Getting a gearbox fault because of an engine fault can happen, more to save the gearbox from a badly behaving engine than it being an actual gearbox problem, though appropriate faults for this can include CAN problems!!

I would, as ever begin by checking the condition of the connectors for the MAF and the MAP. The MAP is in the bulkhead box with the ECU and as well as the wires it has a vacuum/pressure tube connection to the manifold. That could also cause problems if the tube was loose at either end or split. Cleaning the MAF might help. If you do, use proper MAF cleaner and don't touch the actual sensor bits!

Can that scanner interrogate sensors in any way? That could maybe give a steer.

[davidr]

I cleaned the MAF as part of my previous efforts to get the car running right (which turned out to be a completely rusted up fuel tank and pumps) so I think that's OK.
I tried disconnecting the battery and doing a hard dump in an effort to start again with codes etc. Sadly that hasn't made a difference.
I am getting the same codes as well as a P0705 which I think has to do with the gear position switch.

[mike020150]

P0705 is the gearbox linear switch DTC and defaults the car into limp home mode. If you still have access to good spares that you can substitute, it would be worth either trying a replacement linear switch or at least checking its alignment is correct (i.e. check specifically that N & R illuminate when selected since this is part of the installation procedure). The gear selector mechanism has a history of damage and misalignment, some of it caused by drivers attempting to move the selector lever without first having a foot on the brake to release the interlock. Mike.