Our 04 XJ8 (52K mi) was in the shop for inspection. It passed and then when they tried to pull it out of shop it wouldn't start. They couldn't figure out why. Then after about 15 minutes it started but showed something about restricted performance. They read code P1338 out of the computer.

I found some documented info on this code.

Default Action: ECM Default - Fuel Pump feedback control inhibited

Possible causes: ECM to fuel pump control module control and / or feedback circuits: open circuit, short circuit, high resistance. Fuel pump control module failure.

CM pIn: 25,27

DTC DEscription: Fuel Pump feedback circuit. Low / High voltage

I have a few questions:

Where is this Fuel Pump Control Module and what does it look like? Picture maybe?

Could this just be a fluke and should I disconnect battery for ~30 minutes to clear code and restart?

Could this be due to a bad battery? It only reads 11volts with car off and it's a Jaguar battery. Not sure how old it is since we've had the car for only 1 year. IT dropped to 10v when cranking and about 13v once started.

Suggested things to try?

Any help would be greatly appreciated.

 

I think the drive circuit is part of the REM (rear electronic module)
Just clear the code and see if the fault is a one time thing.

An old original battery is something to have tested.

There could be other faults in other modules for a network fault etc.

Pay attention to related problems.

bob gauff

 

Hmm, related problems? Could that include an air suspension fault? I have occasionally leaking front bags and lately the rear is constantly leaking. I was about to switch to Arnott Coil overs until this happened.

I'll get the battery tested and clear the code.

 

Fuel Pump module is intrinsic part of the Rear Electronic Module (REM), in LH side of trunk. It receives commands from the ECM to supply fuel and controls the pump to do this. ECM monitors fuel pressure and temperature at the fuel rail.

 

Thanks for the info guys. My wife just told me something that possibly could be related:

A few time in the last month she came out to the car after it being parked and all the windows were down and sunroof was open. Another time when she walked up to the car and clicked the door opener it also opened all the windows and sunroof at the same time. Not sure if this means anything or not...

 

If you press and hold the unlock button on the remote for more than a few seconds it will open the windows and sun roof. It is therefore easy to trigger it by mistake in a pocket or handbag.

Maybe she walked up to the car whilst pressing the unlock button or the button contact is just sticky.

 

That feature is called Global Opening and it can be enabled/disabled with the Jaguar computer WDS/IDS etc.

You might want to get a complete vehicle scan to see if a network or security system fault exists. Sometimes the answer is looking at ALL the modules in the system to look for faults pointing to a common problem like "system voltage low" in several modules.

bob gauff

 

did you get the problem with your fault code p1338 fixed?

 

Funny you should ask about that now 2 months later. It'a almost like you had a vision into my car's health. It's in the shop now with some kind of fuel delivery problem. It reported restricted performance Thurs while my wife was driving down the freeway and then died completely before she could pull over.

But back to original 1338 code. BAck then I disconnected the battery for about 20 minutes and it cleared and car ran fine up until Thrusday

I expect to hear from mechanic today about it. I suspect either bad fuel pump or badly clogged fuel filter. Just my guess. It's covered under an extended warranty so I figured I'd let them deal with it. Maybe that code 2 months ago was a warning about this problem pending.

I did switch the car from airbag suspension to Arnott Coil spring conversion and she's happy with that since we had problems with front and then back going flat.

 

Had car towed to my normal mechanic. He read codes P1338 and P1699 from the computer. The car died while driving on the freeway with no prior warning. He found the decode info on these forums (2004 XJ8) that it may be the ECM and said it has to go to the dealer for that repair. He measured the voltage and said there was 0 volts at the pump. He determined it probably wasn't the fuel pump if there was no voltage coming to it.

Is there some kind of feedback loop that will remove the voltage going to the pump if it's bad?

Had the vehicle towed to the dealer. Dealer said it's just a fuel pump. The dealer said it is the fuel pump and it will be $1140 to fix it. $650 for the pump alone. He charged 3.1 hrs for the fuel pump and 1.0 hr for the filter replacement. Alldata lists the fuel pump job at .9 hrs!!! When I questioned his charging over 3hrs for a .9 job he got really irritated like a JAguar salesman is known to do from time to time.

I feel like i'm getting royally screwed!!!

My mechanic can get the pump for 20% off the $650 and he will install it for free since I gave him $120 already for the diagnostics only to have it towed to the dealer. (He removed the back seat to measure the voltage at the pump). But if I do that and it's not the fuel pump I'm in a royal mess because I now have a fuel pump and a car that still won't run. The dealer will charge me $135 for 1hr diagnostics if I tow it away.

What should I do??


HELP HELP HELP!!!!!

 

I think you've really answered your own question.

Both your normal mechanic and the dealer have diagnosed fuel pump failure. Provided you have no reason to doubt this, a replacement pump is the fix. Who fits it is the issue.

Understandably you want to come out of this with the lowest possible cost. Although you feel the dealer 3hrs is excessive, I wouldn't like to depressurise a fuel system, remove and replace both pump and filter then test all in 0.9hrs!

As I see it, if it turns out not to be the pump, you end up with a pump regardless of who does the job...............?

Paying the dealer for the diagnostic time and having your normal mechanic source and fit the pump is the cheaper option.

Graham

 

My mechanic thinks it's not just a pump failure becaause the P1338 indicates no voltage to the pump.

That 3 hours doesn't include the fuel filter. That's another hour.

But that isn't right if the dealer replaces a part that isn't needed. When I asked him if they measured the voltage coming into the pump he got irritated and didn't answer. I think the P1338 code warrants a voltage measurement doesn't it... to make sure it is the pump.

 

The DTC's are:

P1338: Fuel pump drive circuit low / high voltage
Possible Causes
REM to Fuel Pump drive circuit - open circuit / short circuit / high resistance
REM failure
Fuel Pump failure

P1699: CAN ECM/CCM Network malfunction
Possible Causes
CAN open circuit fault - CCM to ECM
CAN short circuit fault
CCM failure
ECM failure

The P1388 certainly indicates it could be a circuit issue but failure on the highway tips the balance towards it being pump failure. As there's room for doubt (and for $$$!), a measurement would help pinpoint which it is.

Graham

 

It could be the pump was on it last leg and then blew the fuse, hence the no power to the pump indication. I only offer this idea because of the electric water pumps on my Super. The S/C pump was in bad shape (made a lot of noise) but would pump then blow the fuse. Same with the AUX pump as well. Just my .02

 

So I paid Jaguar the $135 Diagnostic fee. Talked to the Jag mechanic and he said he's sure it's the pump and only the pump. Well it is more than the fuel pump only. The car will start now but runs in restricted performance and immediately after codes are cleared it comes up with P1338 again!!!!

The Jag dealer wrote on the work invoice that "other shop thinks it's an ECM". That was why I brought it to the Jag dealer.... to replace ECM. They assured me it was just the fuel pump. REmember the service manager got irritated and didn't answer when I asked him if they measured the voltage coming to the pump!

I read in these forums that some models have a fuel pump control module. Mine does not. My mechanic called the Jag parts dept and they said there is no control module.

So the saga continues. My car cannot be driven or we risk burning up another fuel pump at $650 each!! I get to go have a discussion with the dealer tomorrow who told me it's onlt the pump... Fun day ahead

Any suggestions how I should approach this with the dealership?

 

you payed the diagnositc fee, now they need to diagnose it.

 

I would agree with the dealer and replace the pump, but if it is not fixed, he will reimburse you for the pump work. If he is so sure, he should make the deal.

 

The old jags had a problem with their electrics. The new jags have a problem with their electrics. Good to know that there is a consistency with jaguar engineering. What worked in the old jags is removing all the electrics (disconnect and reconnect) cleaning the contacts and then bending the fuse prongs for a better clasp of the fuse (Lucas, the inventors of darkness). Maybe the same design flaws are the solution for these xj8's as well. My other suggestion is GET RID OF IT. Many folks walk into these forums with the same "restricted performance" sob stories, some have paid over $5,000 and never figured it out. The dealers are mostly a rip off, sorry to say. question is when do you believe a liar? The simple answer is never. Your story is exactly the same as all stories in this forum and others concerning Jaguar "restricted performance" issues, and the same answers are standard baby-step replies... "what is the code (today)?"..."did you disconnect the battery?"..."did you..." - NEVER a straight answer and the same old advice. I plan to disconnect all my electronics, clean them, spray them with lubricant, and when I am convinced the warning bells won't come on anymore, I'm going to sell it as fast as I can for as cheap as I can!! But what do I know, I could be wrong..LOL!

 

Coming back to the original post, and without knowing if the issue was fixed (fuel pump), I'm surprised to see the low voltages of the battery at the time. A good and chargeed battery should deliver at least 12.4 volts and sustain cranking without coming down to 10volts! When you get 13 volts once started, it's the alternator that delivers such voltage but unclear if it will recharge the battery.
Weak batteries can lead to a lot of issues. Was the battery tested/changed as was suggested at the time?

 

A test procedure for the problem:

1.Disconnect the rear electronic module (REM) electrical connector, CR73.
2.Disconnect the fuel pump electrical connector, FP04.
3.Measure the resistance between CR73, pin 03 (R) and FP04, pin 04 (R).
- Is the resistance greater than 5 ohms?

-> Yes
fix or replace the harness
-> No

CHECK THE REM TO FUEL PUMP DRIVE CIRCUIT FOR SHORT TO GROUND


1.Measure the resistance between CR73, pin 03 (R) and GROUND.
- Is the resistance less than 10,000 ohms?

-> Yes
fix the harness
-> No

check fuel pump drive circuit for a short

1.Measure the voltage between CR73, pin 03 (R) and GROUND.
- Is the voltage greater than 3 volts?

-> Yes
find the short circuit.
-> No

check for fuel pump power

1.Reconnect the REM electrical connector, CR73.
2.Turn the ignition switch to the ON position.
3.Measure the voltage between FP04, pin 02 (Y) and GROUND.
- Is the voltage greater than 5 volts?

-> Yes
INSTALL a new fuel pump module
-> No

check fuel pump power circuit for high resistance

1.Disconnect the REM electrical connector, CR73.
2.Measure the resistance between CR73, pin 04 (Y) and FP04, pin 02 (Y).
- Is the resistance greater than 5 ohms?

-> Yes
fix the high resistance circuit.