Fault messages - Non start

[XJR308]

Hi All
Yet another non- start problem and although 99% of the time it’s the battery but I don’t think it is this time. I think it may be a relay or module has failed.
A bit of background
The car is a 1999 X308 XJR that I have owned for the past 14 years. When I retired the car from daily transport I stored it in a lockup garage and only used it for weekends in the summer and it now has 106,000 miles and has been serviced by a Jag main agent every 10,000 miles.
During the winter I take a fully charged battery down to the lockup, connect it up, start the car and let it warm up to operating temperature, drive it round for a few minutes and park it back in the garage. In the summer months I keep it in my garage at home with a Ctek charger connected.
Now to the problem.
A couple of weeks ago I wanted to use the car so I disconnected the charger and tried to start the engine. When it had performed the system check many fault messages came up such as Low Fluid, No ACS, No ABS, plus others. When turning the key further the engine would not turn over and there was no solenoid clicking.
I removed the ground cable and left the car for about an hour and when I returned I re-connected the battery and everything was now fine. After the system check there were no fault messages and it turned over and fired up first time.
This situation occurred a couple of times so I started leaving the ground wire of while charging the battery and all was fine.
However this morning I disconnected the Smart Charger and re-connected the ground wire as usual but the fault messages came up and the engine would not turn over. I have another brand new battery that although it has a slightly smaller case than the Jag battery it is a 71AH and 650 cranking but this did not cure my problem.
I was going to check the plug connector to the ECU but found it is under a cover that is secured by security bolts so how can I remove this?

Thanks for your help
Regards
Bruce

[Brakebuster]

as you say , battery is always the first thing to check with these cars,

however ,

I would also suggest checking the negative battery cable connection to the bodywork , if this has mild corrosion or is loose in any way from the multiple times you have removed it , this could be the issue ,
there is a main power relay , but cant think where it is at the moment ,

batteries do die, even if well looked after, so don't dive too deep until you have tried a known good new or newish battery , any battery over ten years old will need replacing to be honest

BB

[XJR308]

Hi BB

Thanks for the reply.
In a nut shell:
Leave the car over night with the battery disconnected.
In the morning connect the battery; fault messages appear and will not start (does not turn over and no clicks)
Disconnect the battery check the voltage, reads 13V.
Try another new battery but still the same; will not start, fault messages.
Leave for a couple of hours and try again. Car starts no fault messages.

The leads and connections are all corrosion free and are tight. I am looking for a failing relay or module that sometimes works and sometimes doesn't. The problem is which one?

Regards
Bruce

[RichardSEL]

They may be corrosion free and tight but even a tenth of an ohm can cause a 3V drop on the current path to the starter motor.
And it's that volts drop leading to only 9V-ish being at these (early designed) electronic modules that cause the error messages even though there's no real error there.

I've had this on later cars -- my Passat was an '06MY, others have had it for even later MYs. Difference being the errors get stored in the modules and can be read back. So need clearing -- the icon stays on the MFD

When I was Navy had banks of Lead-Acid emergency radio batteries to look after -- yes they too had those crimped cable terminals.
One of the first things I did when joining a new ship was to solder the crimps. Others did it too. You can imagine the scope for corrosion in a salt spray-laden environment. Can't say I never had a problem -- but sure I had far less than otherwise -- especially on the older creaking hulks I got posted to

Try connecting your negative battery terminal with a negative jump cable to a clean metal chassis point? Any difference between before and after the connection?

Let us know if you find anything different? Good luck

[XJR308]

Hi BB/Richard
Thank you both for your replies they are much appreciated. However, while 99% of electrical problems are down to the battery, or the leads and or the grounds throughout the car, there will be the 1% when it is not. I was hoping someone could suggest the next step in the diagnosis chain.
I wanted to check the plug connector at the ECU but it has a cover held down by security bolts. Has anyone replaced an ECU; if so how do I get at it? My thoughts are to then replace the EMS control relay and then the transponder module. Am I barking up the wrong tree?
Regards
Bruce

[J44EAG]

Hi Bruce,

The golden rule before changing any components is a correct diagnosis done by electronic means. Without that diagnosis, replacing without finding out what parts of the onboard system may be causing an issue, is akin to simply making "shot in the dark" wild guesses.

Many of us using this Club site have equipped ourselves with fairly cheap but effective diagnosis equipment. This saves the cost of taking a car to a garage and shelling out perhaps £70 for something you can do yourself. Popular with many of us is the dedicated iCarsoft 930i unit from UK Diagnostics or other suppliers for around £90. It is a first rate piece of kit which in most instances will tell you where an issue exists. Fault codes are easily cleared.

The second diagnosis kit is very cheap indeed and works with an Android or Iphone. You download the free Torque App, then the Torque Pro uprate which costs around a fiver. You will need to get an ELM327 Bluetooth chip easily obtained via ebay for around another fiver. The V1.5 version is the unit to go for in preference to the V2 version which is not so stable. Toeque Pro is huge value for money and works in a similar fashion to the Jaguar dedicated but more expensive iCarsoft unit. Function wise, there isn`t much to choose between them.

This type of electronic gear makes light work of trouble shooting and will avoid you buying components that may still be succesfully functioning and that don`t require replacement. I strongly suggest you get a diagnostic tool before going much deeper into your present trouble shooting.

Put it this way. Diagnostc checks are the first thing a garage does before commencing repair work. For those of us who have also bought something like a Torque Pro or iCarsoft unit, that is also our first action also, applied before we get the spanners out. Those units can save an awful lot of time, money and frustration. Personally, I never travel without one of those two diagnostic units being present in the car. If a problem occurs on the roadside, I can usually dig myself out of trouble with it and save calling out the rescue services.

Hope that helps.

Mike K

[XJR308]

Thanks Mike for your help.
I do have a OBDII memo Scanner that I use to establish which coil pack has gone down. However when the car starts ok it has no codes stored. when the car will not start it can't find a link. Maybe it is not as sophisticated as the ones you mentioned. I will see if I can pick on up tomorrow.
Regards
Bruce

[Brakebuster]

x308 ecu is under that cover, the screws will come out with some effort ,

bad news is, if the ecu has gone down , then a replacement one will HAVE to be programmed in by jaguar ,

this happened to my x308 ,

but as Mike says, get a hour on a diagnostic machine first, it could save many hundreds in the long run

BB

[J44EAG]

One of the well known items that fail on these V8 models....in fact any V8, is the cylinder head temperature sensor.

I`ve had two go iffy on a V8 S-type and also on my current 350R. Both caused intermitant starting issues when cold when each of them hit 80K miles. Neither showed up on diagnostic gear as being faulty. Replacement of both those sensors immediately cured starting issues and the occasional full hot needle reading on the car dash. Use only genuine Jaguar OE replacements. After market units I know from experience can cause even worse issues.

It is very unusual for an ECU to fail. Yes, pin connectors can get corroded and need cleaning. If the car does run, then an ECU issue is unlikely.

When were the spark plugs changed? Bad plugs will kill ingnition coils very quickly if mis-fires are allowed to occur. If I were on this particular job, the first thing I would be doing is changing all spark plugs and the one duff coil. Until you start from a good solid known base point, there is no point in randomly changing a multitude of other components. Diagnostics and fixes are a logical progression which includes systematically replacing known wearable components and then going deeper if a problem still exists. That would include cleaning both the MAP and MAF sensors, checking the by-pass actuator pipes for integrity, fitting a new CHT sensor checking breather pipes for blockages and air leak free integrity, cleaning out the throttle body throat, fitting a new fuel filter and tightening all inlet trunking jubillee clips. On Sc models, replacement of the small 1/8th ID pressure and vac pipes which control the supercharger by-pass flap also need regular replacement due to heat soak disintigration. Halfords sell that type of pipe for half the price of the Jaguar OE pipe. Its also thicker and appears to be of a rather higher specification.

Seriously, it really is back to basics before doing anything deeper.

Mike K.

[XJR308]

Hi BB/Mike
Thanks for coming back to me and your comments are very helpful.
When the car was taken off winter SORN I booked it in with Grange Jaguar Welwyn for a major service and an MOT. So the Spark Plugs are new and all of the coils are fine. This problem has occurred since that service although I don’t think it could be anything they have done.
I don’t think the ECU is at fault but I do want to check the connector plug for corrosion. Last night the car started normally without any problems and I have left the battery connected and will try again later this morning and report back. I have not noticed any irregular readings on the temp gauge but I will take note next time it doesn’t start.
Thanks
Bruce

[XJR308]

Hi All
This morning I tried starting the car and it fired up first time without any problems or messages.
I checked the battery voltage and it read 12.73V. I then checked the voltage at the Engine Management fuse box and it read 12.73V. If/when the problem returns I will re check the voltage at these points.
Thanks for your help.
Bruce

[Brakebuster]

depending on your issues,

the key transponder on the steering column does go on the fritz now and again,

this usually manifests in a non starting car as the induction coil isn't seeing the transponder in the key fob ,

however, from my own experience of this, I didn't get dash warning lights or messages, just a non starting car ,

the induction coil is mounted around the ignition key , this has a fragile loom going to it that can break and cause an intermittent issue , totally random ,

just something else to investigate and eliminate

BB

[Andy P]

Hi Bruce,
Been following your thread,it must be very frustrating not finding the actual cause of the problem,sorry for not having any constructive idea's for you apart from what BB and Mike have already suggested,there's nothing worse than an intermittent electical fault.
I'll keep my fingers crossed for you and hope it doesn't return,keep us informed with your progress anyway.
Hope you get it sorted.
Good luck,
Andy

[XJR308]

Thanks Andy
Yes Mike and BB have pointed me in the right direction and I think my Volt meter is going to be my best friend through this process as my code reader is no help at all. Fortunately it is not my daily driver and I do have a Lotus Carlton and a Cobra Mustang to play with at the weekends.
I will report back when I find the fault.
Bruce

[ptjs1]

Bruce,

As you've read from others, everything we've seen about X308s over recent years with similar problems tends to initially point to batteries or positive or negative leads. You really need to take readings at multiple points to start eliminating the connectivity and voltage issues.

My suggestion is always to undertake the following routine. You will need some longer leads than typically supplied with a voltmeter:

- Check your battery voltage before off the car before connecting either terminal on the car.
- If ok, connect the battery and then re-check battery voltage at the battery terminals. A slight drop will indicate a parasitic draw.
- if ok, recheck voltage at the positive terminal of battery and a known good earth point on the car. If the voltage has changed, this now points to the battery terminal earth lead.
- if ok, recheck voltage using the positive terminal on the front bulkhead of the car and the negative terminal of the battery. If the figure has changed, this now points to the battery-to-front positive lead. I can't remember how many positive bulkhead points there are on the X308 but repeat the exercise on each one.

Once you've got consistent readings, turn on the ignition and start the process again. Although you'll get a slight drop, inconsistency in the tests will now indicate an excess current resistance somewhere in the leads.

We have often seen problems where the attachment of negative and positive points on the car seems superficially sound and corrosion-free. Disconnect, clean, check and remake each of the connections until you're getting consistent voltage readings on every one of the tests.

This really needs to be your first set of tests before you start looking at ecu connections etc.

Good luck

Paul