hey all. so it happened. i got the scroll of death, all the error messages possible:
- trac not available
- asc not available
- engine failsafe mode
- transmission error
- incorrect part fitted
- er message on the aircon panel
naturally the car wont start but i cant even hook up my obd reader, no data on the obd bus. put a new battery in there, checked the fuses in the engine bay, heel box and trunk boxes, all fine.
any ideas would be appreciated... car is a 2001 xj8, us spec.

 

Possibly a battery connection or ground. Clean the cable connections both at the battery and at the main fuses and ground. If that doesn't do it try cleaning the engine ground strap at the rear right side.

 

The modules are all on the CAN bus. You can check the terminal resistors on each end of the bus for continuity. You can also check the voltage on pins 6/14.

CAN Bus Integrity Check without WDS
– With the ignition switched OFF, connect a DVOM between DLC pin 6 (CAN high [+]) and DLC pin 14 (CAN
low [-]). A reading of 60 Ω indicates a good CAN bus:
< 60 Ω indicates a short circuit on the bus
> 60 Ω indicates high resistance on the bus
– Disconnect the DVOM from the DLC and switch to the voltage scale.
– Switch the ignition ON to position II.
– Connect the DVOM between DLC pin 6 (CAN high [+]) and ground. The measured value should be 2.7 V
(approx.).
– Connect the DVOM between DLC pin 14 (CAN low [-]) and ground. The measured value should be 2.5 V

 

Although the king relays may click on in the fuse box positions it doesn't mean the relay is carrying the proper current to operate the systems pointed out

The focus would be the starter and resolve that and work out from there on a power supply or lack of basis :



So the thing to look at closer on this power approach is ........

See page 51 in link below power point 79 in the square box of the starter relay

Which takes you to page 43 and through the fuse to point 4 square box

Which takes you to page 39 and is a hot at all times power leg through the battery fuse links that do come loose from reading as RJ237 suggest

Now to close the relay to rotate the starter so we're back on page 43 and power point 45 is on page 45 as fuse # 5 / 10 amp Engine Compartment ( different ) fuse box

The power to this fuse is a different power point 4 circle double hash back on page 43 as the Ignition Positive relay ( king relay on the Engine Compartment fuse box )

This one relay I would swap with relay X

Now to get the starter relay to close for starter rotation you need a gtoung wire provided by the Body Processor Module

This BPM has a case ground RJ237 mentioned for proper operation .

The signal for the BPM to command that ground is another ground provided by the ignition switch through pin 1 to pin 5 to car frame ground

Switch is easy to get to by removing the lower steering column cover off with the 2 bottom screws

This connector can get corroded from liquids from above or you can rotate the key to see pin 1 to 5 close

That same 5 position on the socket side needs a good car frame ground that may have been disturbed

This ignition switch is a important component to close all the other king relays around the car for maybe your other issues



http://www.jagrepair.com/images/Auto.../jagxj2001.pdf

Once you get the car started it shiver your timber and put pleats in you pants Capt .

 

Thank you all for all the informations. it was dark yesterday when i got home but before i left i disconnected the battery. after i got home i hooked it up again and the car fired up without a hiccup. i thought it might have been a computer glitch and the reset fixed it but then i tried it again after a few hours and it did the same, error messages all over the place. i left the battery connected and this morning she fired up like normal. i am really puzzled. i havent moved the car, just started up, let it idle for 5 minutes and shut it down. it really makes troubleshooting difficult...

 

Open cell Battery ?

Doesn't need to be the big A8 size for testing

Remember nor to install backwards