Hi everyone , hope you can help me

My 1996 XK8 is driving me nuts with flashing warning lights for faults that don't exist. Has anyone else had this issue? Sometimes they go out for a while then come back on...

Could it be my battery? or electrical fault

Thanks

 

The battery is certainly the first suspect for spurious electrical faults.

Graham

 

How old is the battery? Are both cables clean and secure?

 

Was in the car when i bought it a year ago, looks clean and secure to me

 

Take it to a battery shop and get it tested, typically they'll only last 5yrs (even if they're still good I replace and keep the others as spares).

Haven't you posted in the wrong XK section btw?

Am sure the electrics are significantly different to the older shape.

 

Might be the battery but if it happens while you are driving the car, and it is unpredictable when it will happen, my bet is on a CAN (network) issue.
A new battery will cost you around £100 so unless you are 100% sure the existing one is OK and fully charged, I would replace it.
If the fault(s) continue, you need to get the codes read - any garage will have a basic code reader and shouldn't charge more than £30.00 or so. A jaguar Dealer or specialise d independent will have "dedicated" Jaguar kit, but the cost will be somewhat higher.
A basic code reader and "Torque" - an app than runs on Android phones - won't cost you more than £15.00 or so in total, and is well worth the investment. With an old XK8, you will be using it many times !!


Anything like this ?? : https://www.jaguarforums.com/forum/x...roblem-175264/

 

I have a diagnostic tool and no codes are found.

 

That's surprising. What exactly happens and when .......... "flashing warning lights is" - no disrespect - a bit vague !!

 

Ok so when i fire up the car the warning lights "Coolant Low" and "Brake Fluid Low" appear on the dashboard. sometimes they go out but always come back again time after time. The brake fluid and the coolant are topped up and fine.

Im going to test the battery this weekend, i have a CTEK trickle charger which hopefully should tell me if the battery is no good

 

Aaah at least you've a decent charger.

With an extremely calcified (and flat) battery it can take as long as 4 days to fully recover with a CTEK on it. Hopefully as you've got charge then the weekend should do it.

I'd also be checking all of your grounds including the one for the engine ECU are clean and making their best contact. Not a job I'd want to attempt in these temps without a heated garage but just some quality time with some wire brushes, petroleum jelly and contact cleaner!

 

Do the two warning lights always flash at the same time? As there is no direct common wiring point between them, it could just be you have two separate faults.

The magnetic coolant level float switch is known to fail with false alarms resulting.

The low brake fluid light also indicates from a switch on the handbrake that might be at fault.

 

Wait but didn't the early XK8's have ECU failure? But I doubt something like Brake Fluid Level would be "connected" to the ECU.

 

I experienced both of these when I first purchased my '97. The coolant warning was due to a faulty float. The brake fluid was due to a faulty ABS module.

 

Is your speedometer working? I had all the same indicators + the speedo after replacing the ABS module, had it flashed and all is well now.

 

Coolant magnet float very common problem

 

+1

 

These comments may apply to the early cars only?, .
Both Brake Fluid level and Coolant level switches have inputs to the Instrument Cluster via a multi pin connector at the left base of the instrument pack.
Both circuits are open circuit to indicate .fault.( fail safe )
Coolant switch goes direct to ground from the cluster (single conductor).
The brake fluid level switch is send and return at the cluster ;( twin conductor connector at the reservoir)
Possibles are a poor switch connection at the circuit board,( loose clip on connector?) and/ or a CAN comms. or power supply intermittent.
Access to the 48pin connector is via the under scuttle panel, but take care with moving the connector as it fits to the board.