XJ XJ8 / XJR ( X308 ) 1997 - 2003

No start situation on my 1999 Jaguar Vanden Plas

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Old Feb 18, 2026 | 07:57 AM
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Default No start situation on my 1999 Jaguar Vanden Plas

Enthusiasts im writing this post in search of a solution to my situation. My main issue is that I’m not receiving 12 volts at the grey wire at the harness for my ignition coils. I’ve tested every single fuse box and relay I could find. The trunk box, 2 at the rear seat, and also the ones in engine compartment. I believe there’s 2 on the drivers side and a set of relays where the ecu is located. I checked the main relay (the top one) out of the 6 located near the ecu and have verified that I have constant 12v, hot 12v and a ground with the relay taken out. What am I missing please if any veteran can help me in this matter it’s greatly appreciated.

 

Last edited by Ace VDP; Feb 18, 2026 at 07:59 AM.
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Old Feb 18, 2026 | 01:19 PM
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See page 42

jagrepair.com/images/AutoRepairPhotos/jagxj1999.pdf

Gray wire not recognized in wiring so if you can identify the wire position socket # in this standard connector map

Only one fuel injection relay so may be on wrong item

Your specific fuses are # 5 / 10 amp Engine Management Fuse Box and the relay control power to close relay is hot at all times ( this White / Pink wire in position 1 is not making sense yet )

 

Last edited by Parker 7; Feb 18, 2026 at 01:40 PM.
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Old Feb 19, 2026 | 09:10 AM
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You might check to see if there's power on pin 3 of the relay with the key on. If so, jumper pin 3 to pin 5 and check for voltage on pin 4 of the injector connector. If not, you probably have a break in the wiring somewhere.
The wire from the relay pin 5 connects to the the engine through PI1-53. That connector is the large black one located on the bulkhead held together by a screw.
The fuel relay position is shown on the attached PDF diagram which is under the control module cover for a LHD car. I wish you the best of luck! Whatever the problem, it's fixable with diligent searching!
 
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Relay PDF.pdf (514.3 KB, 22 views)
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Old Feb 19, 2026 | 11:53 AM
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Agree with David on jumpering the relay from pin 3 to 5 once positively identified relay

The auto parts store can make a jumper for you from a box of tools and wire under the cash register made with blade type connectors for best connections

I do not have the V - 8
 
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Old Feb 21, 2026 | 06:45 PM
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I have jumped pin 3 to 5 and do receive power at pin 4 which is the purple wire in this case what does that mean I’ve tested the relay and replaced it aswell.
 

Last edited by Ace VDP; Feb 21, 2026 at 07:05 PM.
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Old Feb 21, 2026 | 07:24 PM
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I have also checked continuity from relay pin 5 to ignition coil wire pin 4 (purple) so I don’t have a break
 
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Old Feb 21, 2026 | 08:18 PM
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On paper page 42 there is no purple wire on the fuel injector relay so is it the correct relay ? I don't have the V - 8 so maybe someone has a pics

In David's doc for a 1999 the relay would be on the car's right of the single file row of relays from car's left to right

Your pic shows a single file row car's fwd to aft , the difference may be the changeover from the AJ26 to 27 engine , there was some wiring if not position changes between the 2 as they did a little changing
 
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Old Mar 1, 2026 | 10:36 AM
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I don't know if that's possible here but my seat didn't have 12v source at all we checked fuses we checked relay everything was fine but the wire didn't have any power so we spliced the rear cigar lighter 12v wire and connect it to the seat directly and the seat now working as it should im not sure if that would work in this situation
 
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Old Mar 4, 2026 | 12:44 PM
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Default Borewashhhhhhh

I was distracted by the ignition coils, in my no start situation the culprit was the iconic phenomenon of borewash. I used a wonderful method stated in another forum and was able to get my Jag running thanks everyone.
 
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Old Mar 4, 2026 | 02:44 PM
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