Hey All,

Im a young guy and was gifted a 96 xj6(x300) and its a beauty. I picked it up, drove it without a hitch. Left it sitting maybe 4-5 days tried to crank it up, and it cranks but doesnt start/turn over. I am not a mechanic and a very newbie car owner, so I replaced the battery bc it was from 2020. Still didnt work. Battery is new, tested, good. Called a mobile mechanic out, he noticed right away that fuel wasnt coming out of the valve on the fuel rail when i turn the key to the on position. BINGO ITS THE FUEL PUMP Relay or the pump itself(fuse is good btw). We swapped an identical relay into the correct socket(green) and still didnt work. Replaced pump, nothing.

The pump wont prime/spin its motor when you turn key to on, but when mechanic put a positive cable(?) Into the positive slot in the relay socket we could hear the pump whir up.

It got dark out, and I noticed that the dreaded 'P' is not illuminating. All the other shifts illuminate. I told my mechanic about this, but he shooed it away because in this case we can start in park, if it was the inhibitor switch we wouldnt hear anything.

He checked the inertia switch, he also noticed there is no spark, no fuel, no nothing, he cant even pull codes with obd II scanner. He thinks the system/anti theft has immobilized the car and is locking him out from scanning for code. I checked this forum and tried the battery terminal reset..nothing. lock door 3 times unlock. Nope.

The man is a trooper and will come back today to check the crank sensor, i will tell him to look for the ecm/ecu connectors..

Sorry for long drabble, i have sunk the money i barely have for parts i dont need and im stuck haha. Maybe someone here has the golden egg.

Thank you.

 

Which country are you in as not all cars had an immobiliser?

 

In the starting sequence the fuel pump will come on for 3 seconds only then off

Fuel pressure will be trapped in the fuel line by a check valve on the fuel pump and the injectors closed

The fuel pump will come on again for the duration of your drive when the CKPS sees engine rotation at a certain amount ( safety design )

The ECU provides a ground to control the fuel pump relay

With a US model it does not have chip in key

The fuel pump relay control power source has a fuse # X which requires the relay in the corner of the right heelboard fuse box , this is different then the muscle power fuse # Y in the trunk , this trunk fuse # Y will be hot at all times

This fuse # X is shaired with the OBD 2 port and I have a better print showing that

The CKPS will read about 1300 ohms as a basic meter reading

You can directly power the fuel pump on socket 3 to 5 , this will drain the battery with the keys in your pocket

You will not have a 2nd fuel pump , V - 12 and supercharged model






You can swap the right heelboard fuse box relay with the left engine bay fuse box relay ( only runs the horn )






Pics coming

 

The not in park switch will make the key barrel click on your fingers as you slightly move it out of park gate

The inirtia switch can be fickle and can be bypassed with a paper clip between the 2 white wires ( low current )

The no crank brings about if the enabling items are powered ( security lock control module ( trunk fuse # 3 or # 4 ) and engine ECU )

right engine bay fuse box relay and back around to the right heelboard fuse box relay for fuel pump relay control

The 2nd power ( used at all times ) to the ECU is the large # 5 ECU control relay , this is controlled by the ECU and brings high current power back into the ECU and well as power directly " sitting " on the injectors and 1 / 2 of your engine sensors

No # 5 relay closing no injectors

 

USA

 

Interesting

These pictures are from the boot...that #2 socket i guess. And some other cables. They were unplugged when i got it and the car was still drivable. Are these cables important?

 

There is an engine speed module in that spot that controls the separate 2nd fuel pump relay if installed , 2nd fuel pump starts at 4000 rpm on the supercharged

There is a shipping diode for the battery that is removed by the dealers

 

Oh that explains it, this car is not supercharged. Thank you. Im trying to learn this car 🤣

 

Oh that explains it, this car is not supercharged. Thank you. Im trying to learn this car 🤣

 

See post # 4 of the link coming up

Repair Manual - Jaguar Forums - Jaguar Enthusiasts Forum

You will have the AJ16 engine which starts on about page 60 of the 801S doc , codes are around 110

A particular about the CKPS is that the single signal may not be discerned by the ECU for fuel pump enable but still give tach ( 300 starter speed ) and spark timing and not have a CEL code of P0335 CKPS

Someone had bent a pin in the OBD 2 connector knocking out the fuel pump control power fuse

And here is a video

 

As Parker has identified in the diagram above, the RH heelboard king relay allows power through fuse 10 when you turn the key on. That white/pink wire is for the fuel pump relay and the data link connector. So if the fuel pump will not prime at key on or run at crank, and you can't get an OBD to hook up, that relay (or fuse 10) could be at fault. If you also notice the brake lights or reverse lights don't work, it proves the king relay is bad (the lighting control module is fed through fuse 14). Swap with the LH engine bay relay as Parker says (that is the horn relay) and test it.

This was the cause of my intermittent starting problem some years ago on my 96 Vanden Plas. It took me months to figure it out!

Don't worry about unused plugs around the car, there are several because not all cars are equipped the same. Also be advised that USA cars do not have immobilizers (more unused plugs).

 

To test the king relays in the corner of the fuse boxes have the key in run but not started

remove the king relays and feel for a click , with the exception of the left engine bay fuse box ( honk horn )

The relay may click proving it is getting the correct command from the ignition switch ( in the form of a ground command ) but the relay can be current compromised by burnt power contacts inside ( again you would swap )

The current may not be enough to properly run your devices down the line

This test exercises the power distribution around the whole car in a nutshell

 

It is easy enough to pop the cover off the blue relays and dress the contacts with some fine emery paper, or just go buy new ones.

Cheers,
Jeff.

 

So I found the answer...it was the ECM. Ecm replaced and car is running. Dont know how or if I need to close this thread. Thank you everyone for your invaluable input!