Bloody car is a nightmare.Best car I've ever owned but certainly the worst for reliability and working on. I have not still got round to finding the faults from the changing of fuel injector number 6. The car just keeps falling apart in front of my eyes. Fuel tank straps and then the rear brake flexy hose started leaking then the bonnet cable kept coming out of the holder so had to strip and clean bonnet catches. This whilst sat on my drive not moving. Parked car in front of garage because I was away the weekend.Even though the car does not run properly I have been able to start it and move when required. Yesterday morning went to start car cranks over fine but no fire. After checking I have no fuel pressure. I've checked all fuses all OK. I'm trying to nail down either the fuel pump fuse or relay but am struggling to find a definite answer on its position. I've have checked the workshop cd manual but this does not help in anyway. Any info would be greatly received before the matches and petrol come out. This heap of a car is taking up far to much time and patience.

Many Thanks

Steve.

 

How did you confirm there was no fuel pressure? Schrader valve on the front of the fuel line? Fuel pumps are not uncommon..

 

Hi Steve,

What is the year and model of your Jaguar? Without that fundamental information it's impossible for us to give you specific answers.

Cheers,

Don

 

Sorry Don wrote the post in not the best of moods. Car is a 2005 XJR.

 

Car is 2005 XJR. No pressure at regulator.Fuses ok need to find fuel pump relay now which I believe is in the boot but I'm not sure which one.

 

Hi Steve,

I understand the bad mood!

IIRC, your 2005 XJR still has two fuel pumps (the 2006 XJRs only have one). The fuel pump relay is R8 in the Rear Power Distribution Fuse Box in the trunk near the battery. You may be able to rule out a problem with the relay by swapping one of the other, similar relays in its place.

It is not difficult to access the fuel pumps since they are under the rear seat cushion. The hardest part of the job is getting that rear seat cushion off, because the four latches can be difficult to access and to move the teardrop-shaped handles to disengage the latches. I think I remember that the tips of all four latches must be pushed toward the left side of the car. I start with the right outer latch, get it disengaged, then stuff the floor mat under the edge of the seat so that latch can't re-engage while I'm trying to release the right inner latch closer to the transmission tunnel. Once I have the right side disengaged, I move to the left inner latch on the other side of the transmission tunnel, then the left outer.

You can download the wiring schematics for your car here:

Jaguar X350 Electrical Guide 2005

The fuel pumps operate on Pulse Width Modulation (PWM) digital signals, but you can test the motors by briefly connecting a 9V battery. The schematic shows that one of the wires to each pump motor is Pink with Black tracer line, and the other wire is Black.

If you can find a friend or mechanic with a scan tool that can read Live Data on a Jag, you may be able to see the fuel pump duty cycle and other relevant data that will help you determine whether the problem is with the main pump (right hand side) or the control system. Also, if you can scan the Diagnostic Trouble Codes (DTCs), the Workshop Manual has diagnostic Pinpoint Tests for many codes that can help you determine whether the pump has failed or there is a problem elsewhere in the system.

You can download the Workshop Manual in six sections in the 'HOW TO' quick links thread on the main page of this X350 forum.

Cheers,

Don

 

The relay R8 is 'non serviceable' ie soldered to the pcb.

If it is faulty you may need to get a replacement rear fuse box.

 

Thanks for the replies guys.Don that info is very useful gives me something to work on I checked the relays you mentioned but made no difference. Merion 1 again very useful info this was what I was afraid of the relay being non serviceable .Do you know if its possible to replace the relay or easier to get another rear fuse box. Something I forgot to mention was when I first got the car powered back up when I turn the ignition on without the engine running the radiator fans kick in and the engine temp gauge goes straight to the red zone.Is this a sign of a faulty temp gauge sensor.
Once again fellas thanks very much for your input.

Steve.

 

Hi Steve,

That may be a very important clue. It may indicate a problem with the Engine Coolant Temperature Sensor or its electrical circuit, and some ECT faults can at the very least trigger Restricted Performance, which inhibits systems such as closed-loop fuel metering and maximum engine rpm. I'm not sure, but if the sensor is indicating a severe over-temperature condition, the Engine Control Module might even prevent the fuel pump from running in order to protect the engine, but I don't know this for certain.

You can download the Diagnostic Trouble Code Summaries at this link:

Jaguar X350 DTC Summaries

Have a look at the possible causes and default actions for DTCs P0116 to P0125

I think you really need to have the vehicle scanned for DTCs to help narrow down your diagnosis.

Even a basic inexpensive OBDII scanner can read the Powertrain DTCs (P-prefix). The P-codes may not tell you the whole story, but they may tell you enough. If you can't find a scanner locally, an excellent low-cost option is an ELM327 bluetooth OBDII adapter available on eBay for under USD $10.00, in conjunction with the Torque Pro app for Android phones (USD $5.00), or an equivalent app for iPhone.

Please keep us informed.

Cheers,

Don

 

The R8 relay can be repaired but much easier to replace with another fuse box.

I would buy an used one a new one will be very prohibitive.

 

Thanks Don for the reply. I have Jag software Mongoose sdd on my lap top. At the moment the only locked related dtc is P1235 (Fuel Pump Control out Of Range (Fuel Pump Driver Module/VLCM). I think I will replace temp sensor first just to eliminate that from the process then get back to fuel pumps or relays.

 

Thanks Merion I thought that might be the case.

 

Hi Steve,

I'm not sure that the temp sensor is a suspect unless you have other DTCs that point to it. Here are the definition and possible causes of P1235 from the DTC Summaries guide I linked to earlier:




This suggests a problem with the circuit between the Engine Control Module and the Rear Electronic Module, which is mounted on the right inner wheel well behind the carpeted trim panel. Problems with the harness and electrical connectors in that area are known, and there is also a ground stud nearby that is referenced by the REM. It would be worth disconnecting battery, then disconnecting and cleaning all the electrical connectors associated with the REM, and the ground stud referenced by the REM. The Fuel Pump 2 Module and Parking Brake Module are also there, so clean those connectors too. Fuel pump control is handled by the ECM in partnership with the REM, Rear Power Distribution Fuse Box (RPDFB) and Fuel Pump 2 Module. You can see the schematic on page 67 of the Electrical Guide, which you can download here:

Jaguar X350 Electrical Guide 2005

The ground stud, nut and eyelet terminals on the wires are all made of aluminum, and a thin, 4 nanometer layer of aluminum oxide forms on them and adds considerable resistance to the electronic circuits. Use a brass-bristled brush and zero-residue electronic cleaner to clean the components and reassemble. Note that the torque spec for the ground nuts is a very low 6.5 ft. lbs., which is just barely more than hand tight. Several of our members have discovered the hard way how easy it is to snap a ground stud off of the body by overtightening the nut, so take care not to make your job even more difficult. While you're there, disconnect the two battery negative cable ground studs and clean them also, along with any other ground point in the right rear corner of the trunk that might be referenced by the RPDFB.

Inspect the wiring harness that goes forward into the passenger compartment near the trunk hinge area for any visible signs of stress or damage. The fuel pump supply wires are part of that harness and come down behind the rear seat.

Do you have any other DTCs that relate to communication issues with the REM or RPDFB, possibly U- codes related to the CAN? Sometimes it can be difficult to associate related codes, so if you have time, please post all the DTCs here just so we have the complete picture.

Cheers,

Don

 

There is a bunch of other dtc's. I will hook up the laptop and get some codes.
Thanks Steve.

 

Well the heap will not start know. Some more codes have appeared but the pain is the gearbox fault.It will not come out of park so I can't even move the bloody thing. How much are 2005 XJR's worth non running. I'm getting very close to giving up its taking to much of my time and money.

 

Hi Steve,

I understand your frustration. The first thing to check whenever you get a lot of DTCs is your battery. How is its health and state of charge?

Regarding the transmission, this could be battery-related as well. If your battery is strong, have you checked the bracket on the left side of the gearbox where the shift cable attaches? The bracket is secured by two screws and the screws are known to loosen and even fall out.

When you get the chance, please post all the DTCs so we can see the full picture.

Cheers,

Don

 

Your reading my mind Don. Battery was fully charged couple of days ago. I checked voltage earlier today and it was reading 12.1/ I know these cars are very sensitive to battery issues. I think I will replace mine just to eliminate that problem. I tried reading dtc's but was having problems getting it to work could this be down to low voltage as well. Codes at the moment are P1582 showing 50% P1235 showing 100% and B2139 100%. One thing I have found was water in the passenger foot-well by the ecu where I've got a lot of the plastic shrouds removed from the engine bay. I've tried keeping it waterproof but obviously did not work. I'm waiting for a 5 sided Tamper-proof T30 torx fitting which I believe is correct for taking out the ecu loom plug in the engine bay. Once again thank you for your input Don it does motivate me to keep going.

Cheers Steve.

 

Finally got around to taking the ecu out of the car . This is what I found.For a prestige car it has some poor design faults especially this on such an important part of the car.If your ever under the bonnet make sure your drains are clear and check for signs of water under the glove box .Anyone recommend a good cleaner for the Pcb. I have some isopropyl alcohol would this be OK with a soft brush.

 

Spray electronic component type of cleaner might be a better option.

 

Hi Steve,

Thanks for this great reminder about keeping the drain below the ECM clear. Every X350 I have worked on has had a pile of leaves and seeds filling the drain, and mold growing on the cabin air filter.

Isopropyl alcohol might be fine to clean your circuit board if it has no oil content, as some rubbing alcohols do. As Wingrider suggested, a better choice would be a zero-residue electronic cleaner. A brand available at most auto parts stores is CRC:


Note that CRC also makes a product called Lectra-Motive Electric Parts Cleaner, but it contains aggressive solvents for cleaning alternators, starter motors and such, so it is not what you want for your circuit board or electrical connectors.

Cheers,

Don