I’ve never posted a forum before so please bare with me. I just purchase a 2003 Jaguar X type 3.0L V6. It had 14 trouble codes which I diagnosed and fix 13 of the 14.I’m a DIY guy and for awhile I’ve been fighting with the P0191 and also the battery light ever since I had brand new alternator put in. But with the P0191 Its pretty much been a guessing game with the fuel system. Fuel pump kicks on when I turn key so I don’t believe it to be the actual pump (I HOPE NOT) Here are the things I’ve replace do to the DTC

1.Fuel Filter
2.Fuel pump Driver module
3. Gas cap
4.Cleaned injectors
5. Replaced regulator
6. Replaced Fuel Rail Pressure sensor and connector

 

Regarding the battery light: one VERY common source of this is a corroded battery lead, either positive or negative. They corrode internally, that is under the sleeve where the corrosion is unseen. Test by having the engine on, fans running, lights on. Hold your hand over the battery terminals. Be careful! You are testing to see if one or both are significantly hotter than other components nearby. If one or both are, you have found the problem. I had exactly this issue and symptom (the battery light), fixed by replacing the HOT positive cable.

 

Sorry I forgot to mention I replace both positive and negative batt cables. Here’s what the Jag is doing. Upon startup (Every startup) after about 5 to 7 seconds at idle it will stall almost to the point of dieing out but it won’t. And normally after about another 15 seconds it will pick back and idle normally. Brand new battery as well. With vehicle off on dash batt voltage fluctuates from about 11.8 to 12 and with engine idling about 12.9 to 13. Also have a engineer dash code that states Generator C line input low. Maybe that has something to do with it. Thank you for your reply!

 

Xhampul, from the sounds of things, you have a damaged wire in the harness. I would start with the wiring to the fuel rail pressure sensor. Make sure your splices are good (I recommend stripping back about 3/4" of wire on each end, rolling the wires one over the other to twist them together and then soldering them at that point, then covering in Raychem to make sure you will not have future problems, if you don't know what Raychem is, let me know). Then keep following the wires all the way to the ECU. You are looking for anywhere the wires make a sudden bend (indicating a broken wire inside the insulation) or the insulation has been removed from the wiring. After that, you have done pretty much everything else. The only other possibility that I could possibly think of is the line on the fuel pressure regulator, if that gets damaged, that can affect your fuel rail pressure and the computer may be fighting to get the amount of fuel in the cylinder under control when it is bogging down.

 

Thanks Thermo! I will look into it in the morning and update you. Much appreciated 🤜🤛💪

 

Xhampul,
Just circling back to the alternator replacement you have done......did you fit an original replacement alternator, or an aftermarket non-Jaguar one?
Our original alternators are controlled by the ECM, so fitting a non compatible aftermarket version will likely give you some charging issues.
Immediately after you start the car, the alternator will be instructed by the ECU to produce maximum output voltage in an attempt to quickly recover the battery.
You should see round 14.5 to 15 volts being sent to the battery for a minute or two, before the ECM then instructs the alternator to provide the lower sustained output charge voltage (around 13.2 to 13.5 volts).

 

First knock sensor I bought brand new I assume it got drenched in coolant due to P0332 so I purchased another one this one is saying p0333 so I ended up running a new harness shielded wire but im confused as to how to make the connections from the connector to the ecu. There are 2 conductors with what seems to be a shield bare aluminum ground. Someone please explain in detail how I’m supposed to make up these wires correctly. Or bypass it if I have temporarily (rather not do this but will if I have to get on the road).

 

It appears according to the schematic that the original knock sensor wire colours are brown and white plus a surrounding cable shield.
First check with a multi-meter good continuity between the sensor wire shield and the sensors white wire. That should measure almost zero ohms. If very high resistance or open circuit, check to see if shielding measuring instead to the sensor brown wire (just in case).
If cable shield is measuring internally to the white wire, the following steps are the way it should be connected.
The sensor Brown wire is the signal wire that connects back to the ECM plug pin 98 within the loom as a Brown wire.
The White wire is effectively treated as a ground wire, joining within the engine harness to the Black/Green stripe wire that starts back at pin 100 of the ECM plug.
Note: That Black/Green stripe grounding wire from ECM does split out within the harness to also service grounds for the crank position and both cam position sensors as well.
(If you find the sensor's cable shielding is internally connecting the sensor's brown wire instead, then reverse the instructions above).

As mentioned above, the aluminium shielding of the knock sensor cable should be ultimately connected to the White wire connection as well, so the sensor cable is effectively shielded and does not pick up undue interference induction.
If you did not measure zero resistance from the cable shielding to either the White or brown wires, then you might need to carefully cut back some of the outer insulation sheathing to expose some of the foil shielding and securely overwind some thin copper wire around the exposed portion of the shielding to give you a workable connection point to it that can then be incorporated and joined to the white wire joint with the Black/Green stripe. You will need to make all of these joints mechanically robust and water tight for longevity.

From a final measurement test, your White sensor wire should measure low resistance (less than 2 ohms) back to pin 100 of your ECM plug (and I expect car ground).
While the brown wire from the sensor should measure low resistance back to pin 98 of the ECM plug.

Hope this helps.

 

MUCH appreciated! God bless you man!

 

I saw you mention about aftermarket alternator. Last month I replaced my original alternator with a brand new Denso. Ever since then the battery light stays on. I’ve tried just about every route in my knowledge I could. Ran a switch with a semi conducted ended up getting to high of voltage. Anyway. My point is do I need to wire the plug differently then the original OEM alternator?

 

What part number was the Denso alternator you fitted?
It might not be compatible with the charge level control signal sent from the ECM.

 

R111175A

 

The part number for an original alternator is C2S3710

so my hesitation is shopping online there are numerous Denso brand alternators that sellers say they fit and work.. BUT... if you go to Denso's website, type in our car it returns NO PARTS FOUND for their brand alternator. I think the manufacturer would surely know best?

 

This is the alternator.

 

I know, let's argue empirical evidence because it doesn't fit what I want to be true...

 

Ok what type and where can I get the right one

 

Just enter the part number in search engine and it will give you the results = AGAIN C2S3710. And if one of the forum sponsors have it, mention that for a discount.

 

While you researching and sourcing the recommended alternator, please also take a moment to just double check the 10 amp fuse # F82 in your central junction fuse box.
That feeds a supply line to the alternator's internal control module via pin 2 of the alternator plug (Green/Red stripe wire), so if it is open circuit then you might expect to have no charge activity from alternator.
That fuse also feeds a few other minor functions in the car (reverse light switch - only on the manual transmission versions) and the auto tinting function of the rear view mirror, so you are not likely to notice those functions missing....but the charging you will.

Also check that your main charging wire that goes from the alternator to the starter motor terminal to make sure you don't have an issue with that (corroded contacts or open circuit).