2004 jaguar x type fpdm issue

Hi everyone, I am trying to diagnose my car, the issue is that the car starts and stalls a few times before it will stay running. after it start it will die out and when it finally wants to stay running, it runs great. I did a scan for codes and p1234 is whats coming up which translates to fuel pump driver module off line or disabled. I have the service manual to the car, but I don't understand how to go about testing it. I have attached a wiring diagram to this post. Any help would be appreciated. thanks.

The fuel system is an electronic returnless system the fuel pressure is controlled by the the PCM (Engine computer) telling the FPM (Fuel Pump Module) to control the fuel pump speed by changing the PWM (Pulse Width Modulation) of the voltage supplied to the fuel pump.

The code means the engine PCM cannot control fuel pump module, this could be a fault in the FPM or control wiring between the ECM and FPM or the PCM. The fuel pressure sensor (FPS) at the engine is also a corncern. You should also check the power and grounds on the FPM.

Your Jaguar is essentially a Ford these video show the Ford system but a different fault.

thanks for the help, i did verify the powers and grounds yesterday, but i did not know that the ground to the pump was pwm. Now can I test the wires to the pcm with a regular dvom? I don't have a lab scope. another thing is that in the wiring diagram i do not see an inertia switch, but i know it has one. so i will take the passenger side kick panel apart and check the wiring colors.

Thanks for posting that diagram! Like Andy said, it appears your FPDM operates just like the rest, aside from a couple additional signal shield pins.

In addition to the videos already posted, you can check out this recent thread for some more theory/operation and known good waveforms:

scannerdanner.com/forum/post-your-repair...50.html?limitstart=0

Now can I test the wires to the pcm with a regular dvom? I don't have a lab scope.

Absolutely! The source of the P1234 is going to come from the Fuel Pump Monitor circuit, which is the FPDM's response back to the PCM about how things are going at the FPDM. Based on the diagram you provided, I'm guessing it's gonna be pin 7, white wire at the FPDM. Backprobe this pin and see what reading you get.

another thing is that in the wiring diagram i do not see an inertia switch, but i know it has one. so i will take the passenger side kick panel apart and check the wiring colors.

Perhaps it's on a different diagram? Not too familiar with Jag diagrams, just wondering if "40-E" points to another page. I figure the inertia switch is good, as you can eventually get the engine to run. If the switch were tripped, then the FPDM would never give you fuel pressure.

pin 9 is the power to the fpdm from the ignition switch. I believe that that wire is coming from the inertia switch and it has battery voltage when koeo. the white wire is an output so i will definitely take a look at that. i did order some back probes and piercing probes. once I receive them I will do some more testing and get back with my results. thanks for all your help.

Jags do generally have an inertia switch but I don't think it has tripped. I would do the wiring checks but also eBay for used module it is the same Ford part as the V6 Mondeo

I've had success using FPDMs from a variety of cars. I'm not saying they're definitely ALL the same, but I've used a Focus one for a Continental and a Contour (which I believe is a Mondeo).