Hi,
I bought a 2007 XKR (4.2 SC) from a questionable fellow about a month ago. From day 2 it has been nothing but trouble.

First problem: On start-up I had ABS, DSC, CATs warning lights, car was in limp mode - On restart it drove fine until approx. 15miles later where it went into limp mode again on a long sweeping 50mph bend/hill. Again, cycling the power fixed this. (My first thought was an ABS sensor/battery issue. This has not happened again.

Current problem: Seems to have developed into a more serious issue
Symptoms (all at once):

• Multiple warning lights on dash
• Revs and Speedo drop to 0 (I have also experienced dial flickering below 0 when ignition switched on)
• Steering goes heavy
• 'Gearbox fault' - Gearbox slowly works its way down to approx. 3rd gear (some kind of failsafe get you home ratio) - Cannot influence gears with paddles
• 'Temperature indication fault' accompanied by Rad fan permanently on
• 'Brake Fluid Low'
• 'ABS Fault'
• 'DSC not available'
• 'CATS system fault'
• 'Park brake fault (amber)'
• 'Park brake applied (red)
• Seatbelt pulls in (pretensioner?)
• When engine stop button pressed it displays 'engine stop button pressed', it will turn off if tried again. but will not restart (just cycles through ignition on/off.) If left for approx. 15 mins it tends to restart (but with a short press of the ignition and NO FOOT ON BRAKE). At which point there may still be lingering issues with parking brake, gearbox etc.
• Engine when running functions as normal

Cannot communicate with any modules from OBD port - Lots of errors (i.e. Lost communication with steering module, Lost communication with instrument cluster, parking brake control module, abs module, gearbox ect. Plus a canbus

• Intermittent vehicle speed sensor A (I assume this is a calculated speed value from a module)
• Intermittent speed
• Intermittent steering column lock (don't usually check but the lock is rarely actually applied)

The last straw was after recovering home and leaving the car to sit for an hour, I was greeted by 'Parking brake fault, cannot apply parking brake' and lots of beeping. No life from the handbrake motor, I could tell at least one caliper was not releasing as I had to move the car out of the way to get my backup mx5 out.


Thing I have done:

• A new Yuasa 019 battery has been fitted with problem still persisting.
• Cleaned earths in boot, behind headlights, cleaned ABS connections at front
• New rear lamp brake/side bulbs

Separately, but possibly related:
New battery backed sounder (although part number slightly different), no longer displaying fault codes.

I am no auto electrician but I'd imagine the issue relates to a module with bad ground, earth or shorted canbus wires scrambling the whole network. - What steps can I take to diagnose (e.g. checking voltage/resistance at OBD port etc when it next happens?

 

My thought, as was yours, points to the battery as the usual suspect. I would fully charge the battery (could have been on the shelf for months) with a real, 10 amp or more, charger (not a trickle charger or maintainer). A fully charged battery should be 12.6 VDC or a little higher with the car off. With the car running, you should measure around 13.5 to 14.5 VDC if the alternator is working properly.
And grounds are a good suspect as well. There are multi-ground points in each front wheel well which are susceptible to corrosion. The attached diagram may help in finding other grounds (prefix "G" in the diagram) to check. G2 and G3 are the ones in the front wheel wells I think.
Please keep us posted on what you find.

 

I am doing canbus diagnostics on my 06 str myself. I am a rookie in auto wiring. I learned a lot by googling canbus diagnostics with a multimeter and learned a heap of info. Then i was able to use and understand the pinpoint tests in the workshop manual. Give it a look see

 

The new battery was an off the shelf item, but it was able to start the car and drive for 20 miles before the fault occured again. I think this rules out battery?

The previous owner claimed to have changed the alternator, so I will check for loose connections there, or damaged connectors.

I did see a while back a technical service bulletin for a different Jag model which shared some symptoms (dials dropping) - this advised to check all canbus plugs for loose terminals.

One code that stands out to me?

 

Absolutely it does NOT rule out the battery. Starting has nearly zero to do with running electronics.
Everything you described IS a symptom of a bad battery. Not saying YOURS is, but wouldn't that be better than replacing the entire CANBUS?
Charge it as stated above and try everything again. Also, before you reconnect the battery cables, touch them together for a few seconds, totally disconnected from any part of the battery. That's a HARD RESET. Can't hurt, may help.

 

Starting again after a short sit sounds like a battery recovering a little so it's definitely #1 suspect.

 

To me such troubles looks like there's been an electrical shock or an electromagnetic damage... Such as a thunder shock nearby or something like that.
In the past I had electronic stuff who turned crazy like this when working in a manufacture...And we discovered it was because of a workshop nearby who had been hit by thunder few days ago.
I would suggest an hard reset and leaving the car out of any energy for few days, the longest the better....while charging the battery at it's maximum. Might worth a try before thinking about huge work on the wires.

 

Bit of an update. I went back to the car to do a little digging. At first I opened the boot to check voltage and heard the dash beeping manically as it did a few hours earlier when I left it.

Battery 12.7v resting. My point about battery being ok was that after 20 miles of running the alternator likely would have maintained a healthy charge (Unless there was an issue with the charging system).

I then disconnected the battery for approx 1hr while I went round the car and checked other earth points around the A posts, and pulled apart and reseated any plugs in the footwells, central junction box, brake switch etc.
I also removed the instrument cluster to inspect the connectors.

By the time I had put it all back together the handbrake warning had gone and I have been able to make the last 2 trips to work without issue. (Previously disconnecting battery and holding terminals together did not solve the issue)

I've either fixed a bad connection, or more likely the hard reset has cleared something. I'm still sceptical and will continue to monitor.

One thing I have noticed is an occasional change in the sound of the indicators. At times it would sound more like a 'clack' than a click, which is what prompted me to investigate the instrument cluster. This made me suspect a bad circuit/water ingress etc.

 

Good to hear you may have sorted out the problem.

 

I suspect that the connector dis/re connect helped clean the contacts significantly. I sometimes wonder why Jag/Ford couldn't gold plate all of the connectors. Seems that the slightest drop in voltages (signals) starts a ball rolling which is so sensitive @ deviations from ideal that the poor old jag computer can't cope. Anyone remember windows 95 or 98, the first question from IT service, "did you try unplugging the computer and then..."?
or am I showing my age

wj

 

"Shake the Abacus and try again".

 

Drove across town today. Had the car parked in the sun for a couple of hours. When I turned the ignition on I had a few faults again :/

'Steering column locked'
'park brake fault'
'Abs'
'Brake fluid low'

Ignition cycled again and I was able to start with CATS and engine light on. No cruise available.
Was able to select gears from the paddles although no rev matching (presumably due to engine light).

I'll see how it goes but will read the codes again and list them here.

 

Car has been fine for just unde a week, however the faults returned today approx 15mins into my journey home from work. Same as before but this time I still had gears.

DSC fault came first, followed by parking brake and abs faults. Could not open filler cap (annoying as I wanted to refuel)
Left car to sit for 5 mins and it started but could not get out of park. Turned off and on and was able to move to the fuel pumps.

Started again with no faults, however a min later the errors came back.
At random points I could hear a relay click (sounded like the usual parking brake click) occasionally accompanied by the parking brake light going out. Then back on.

Is it common for the parking brake module to fail (e.g. poor solder joints etc?)

What checks can I do if I suspect a faulty module?

Does anyone know of a reliable auto electrician in the SW (Gloucestershire).

 

Fault codes (brake codes cleared and did not return)
B1005-96 & b1005-31) new pedestrian sensor on order to fix this)
B1A69-01 Humidity sensor circuit - permanent

C1D15-64 intermittent brake switch status
C1803-00 intermittent motor disengage full travel distance not reached upon release

U0001-00 intermittent high speed canbus

 

Some additional symptoms.

On every journey to work this week, approx 10-15 mins I to my journey I have had a permanent DSC fault and intermittent parking brake fault with red/amber brake warning lights come on and off randomly during journey, accompanied by clicking of relays between the rear seats.

If I park up when faults are present, on returning to the car after work the engine will start without foot on the brake. ​​​​(Potentially issue with brake pressure switch?)

When the fault develops and everything goes into meltdown, I have noticed the seatbelt pretensioner tugging at my seatbelt, relay clicking from this area. Possibly a symptom not a fault.

I suspect the EPB is a good starting point for diagnosis so I will get the multimeter out for some checks.
Failing that I will try a local independent for diagnosis.

 

Humor us. After a night of the car sitting and not running; in the morning, without the car running, take a battery voltage reading.

 

Tried checking the voltage before setting off to work today but the boot wouldn't open... Tried again this afternoon and parking brake fault was displayed on the dash at the time. 12.6v.
Anyway, I have booked the car in with Northfield Garage (Jaguar Specialists) in Birmingham.

On the phone he mentioned an additional set of earth points in the front wheel arches.
​​​Had a look this afternoon and located a couple on the chassis legs.
Took the R/h earth off to clean it and one of the ring terminals fell apart in my hand. Will repair the loom and report back!

 

Ya, grounds will get you - I had the same problem but it only affected the headlight adaptive system - what I did was this drill and tap the chassis described here- you would need to get some new ground lugs from an automotive store and redoo the wiring to them

https://www.jaguarforums.com/forum/x...cators-240302/

 

New ring terminal crimped on, however doesn't look like this has solved the issue. After a couple of mins at idle the faults appeared again.

I measured the resistance between pins 6 and 14 (can high and can low) on the diagnostic port as 105.7 Ohms. (During fault)
Am I right in thinking this indicates one of the 120 Ohm resistors is 'missing', indicating a module containing one of the terminating resistor is faulty, or wiring fault in the circuit?

Which modules or wires contain the terminating resistors?
I will make a separate thread with the facts to narrow down the response.

 

your reading is ok. 60 or so ohms means a possible bad resistor or module with everything plugged in. On my car the resistors are in the abs module and the ecm. Yours might be differen. Unplug a module and then check the two pins again. When you get 60 ohms or so you have found one. It is best to disconnect the neg terminal at the battery when disconnecting or connecting a module. It will not affect your ohms test. The module should not be awake in any way when messing with plugging or unplugging it. I just went through a similar canbus issue. Google up canbus diagnostics and you will find some very helpful info on troubleshooting