Hi All,

First post but having a sticky problem trying to get my X306 to run. It's been laid up for about the last three months in the garage awaiting some repair work for an unrelated issue. Three months ago it was starting and running fine.
I had the car connected to a trickle charger just to make sure the battery staid in good nick over time.

Yesterday I went to do a bit more work on the car and noticed that when I opened the door, none of the lights came on. Everything was dead. I noticed my trickle charger wasn't charging the battery, and it appeared the battery was REALLY dead.

I'm unsure why this happened, but it's possible that my tiny trickle charger couldn't keep up with the parasitic drain on the battery and the battery just drained over time until the point where it'd no longer accept a charge.

I managed to get into the boot/trunk by jumping the terminals on the kickboard fusebox with a spare battery to raise voltage and pop the boot/trunk lid.

Once there, I managed to use the other battery to jump the car's battery to the point where it's taking a charge. I've left it on my big charger overnight (with the battery disconnected from the car) and the battery seems to be reporting good voltage again.

Now everything works as it should but the car won't crank at all. Just turning the key to the start position gives nothing, no clicking or anything. Even with the second battery jumping the car still nothing. I've looked through many threads and here's what I can tell you to eliminate things:

1. My car is an ex-Singaporean car and I don't believe it to have an immobiliser (no antenna ring near the key). The alarm works and beeps / locks / unlocksas it should.
2. EVERYTHING else seems to work normally. I've seen that with some other people who have had other issues such as a bad Body Processor Module, there are other things that occasionally don't work in these situations like door locks, wipers, interior lights etc. None of that with my car, everything seems to work as normal.
3. When turning the key to position II the warning lights all illuminate and extinguish after 5 seconds. The CHECK ENGINE light stays illuminated as per usual.
4. I get the red "P" on the transmission. In key position II I can use the brake to disengage the interlock and move it to the other gears. No cranking in either P or N.
5. I've gone through and checked practically every fuse and they all test fine.
6. The car has been stored in a garage and hasn't moved in all this time. There's nothing to suggest that anything has moved or disturbed or corroded in the last three months which would have caused this.

I was worried that perhaps in connecting up the other battery to jump the system to unlock the boot something might have blown a fuse or fried a module but everything else still seems to work as per usual.

The only thing I've got left to try is to just leave the car connected for a couple of days with the healthy battery and try again. I have seen one or two other people had similar symptoms where a car had been connected to a dead battery and had similar non-cranking issues that resolved themselves after staying connected to a good battery for a number of hours/days. I don't THINK this will do any good, because surely you should be able to just connect a good battery to a dead car and be on your way within minutes?

My next steps are to check the starter relay pin voltages and try umping those pins to see if the starter turns.

Any ideas what further diagnosis I can do?

 

Information provided verbatim by Gerald on the Jag-Lovers forum as initial first steps to be taken if it won't start.

Here is a list of relays I think you should check (by substitution with a new one, if possible). Also some other items to check which could posssibly be causing problems.

A critical relay is in the RH under-bonnet fusebox. This one switches the supply to the starter relay and ignition coils (via fuse 12), also the oxygen sensor heaters (via fuse 14).

Whilst you're in that fuse box, check the condition of fuses 6, 11, 12, 14. These carry supply current to various parts of the engine-management system.

Also critical is one of the sealed black relays in the row immediately behind the RH headlamps. It's called the 'ECM controlled relay' and it switches power to the injection system. It SHOULD be the extreme right-hand relay of the group but it has been known for the order of the relays on the bracket to change. To be sure of finding the right one, look for the relay that has 4 wires of colours brown-yellow, brown-orange, black-lightgreen and brown-purple going into its base.

There's the fuel-pump relay which is known to give trouble at times, although I'm not sure that your symptoms point to that. Still worth checking, though. You'll find it in the fusebox in the boot. It's a black relay on a red socket. I think it's the third from the rear in the row of 4.

Also worth a check is the relay in the RH heelboard fusebox which switches the supply to the OBD2 socket and fuel pump relay(via fuse 10).

The fuse boxes (and starter) are supplied by a network of very thick cables from the battery positive terminal. Joints in these cables are bolted using bolts that go through various bulkheads. These points are notorious for corroding (see the archives) and give rise to all sorts of electrical gremlins, one of which is that the starter won't operate when it should. Note also that the thick connection from the battery negative terminal to the bodywork has been reported to suffer the same problems from time to time and will give rise to some equally odd happenings.

Finally, don't forget the white 13-pin connector behind the RH headlamps. Check it for corrosion, particularly the pins connecting to the green-black, brown-yellow, white-pink and brown-orange wires. Problems on these connections will cause engine-running or starting difficulties.

There is a Jaguar Technical Bulletin outlining the actions to take if this connector deteriorates

Connector PI1 (13-way Econoseal III LC white, located behind RH headlamps):

my 1995½ - the white connector is lower of the two

Jaguar recommend moving connector up to here

Pin-out of the white connector

Pin 1 - white-yellow, air-con single pressure switch to inertia switch.
Pin 2 - green-black, fuelling inhibit from ECM to SLCM
Pin 3 - brown-yellow, from fuse 11 to ECM relay contacts
Pin 4 - white-pink, from fuse 12 to ignition coils & starter relay
Pin 5 - white-orange, evap valves (only on V12 ?)
Pin 6 - brown-orange, from fuse 6 to ECM relay coil
Pin 7 - red-slate, washer jets temperature sensor
Pin 8 - orange-slate, oil pressure switch
Pin 9 - orange-pink, temperature gauge sensor
Pin 10 - (no connection?)
Pin 11 - pink-black, 2nd fuel pump relay (only on V12)
Pin 12 - red-orange, RH fog lamp
Pin 13 - blue-white, LH main head lamp

The colours listed are as per the circuit diagrams on the CDROM. Of course, it's not unknown for reality to be somewhat different to what the paperwork claims!!

Early cars (like my 1995½) had this connector fixed to a metal bracket quite low down and it was prone to filling with water. Later cars had the connector strapped up to a wiring loom a couple of inches above the original mounting bracket, presumably in the belief that water was less likely to find its way into the connector.

It might just be worth mentioning that the relays in the fuse boxes are themselves powered up via the inertia switch. If that should be intermittent (although I don't recall any reported cases of this), it could cause all sorts of failures . . . .

 

I got it sorted tonight. With a fully charged battery it still wouldn't crank. However, a bit of playing around and I got it going.

Turns out it's the Park/Neutral switch on the gearbox. While it was obviously detecting it was in Park (Red P), the gear lever needs to be pushed slightly to the left (in both Park and Neutral) to get it to turn over. Then it fires right up.

I'm guessing the switch needs some kind of adjustment (I seem to recall that being possible) or perhaps a bit of contact cleaner is required.

I've got to pull the ski-ramp off in the next couple of months to fix a couple of minor things so I'll add it to my list of things to do while I'm there.

 

Bumping this instead of starting a new thread.

My XJR (x300) has always had weird voltage issues since I got it, if you put the heater or lights on you can notice the voltage drop at the dash gauge for example.

It's sat for a few months outside and had a dead battery, charged this up to 14v and when I stuck the key in the car it was showing 12v(ish) on the dash gauge. Tried to start the car and nothing happened. Checked voltage at the battery again and its been zapped right back to 12v again. So far I've removed the nuts and cables from the 3 battery posts on the engine bay firewall and the white insulator looked to be in good condition. I've cleaned the battery posts, cleaned the earth strap by the battery, checked all the fuses mentioned in the post above and still the same issue. I fully charge the battery, turn the key and it drains it instantly to flat.

Any ideas what this could be? There are so many fuses boxes and relays in this piggin' car that I'm slowly losing my mind.

 

Try disconnecting the main alternator lead and try again.

I saw a similar scenario on a friends car (not Jag) and was the alternator shorted internally (regulator?).

Just an idea.

 

I've only noticed there after reading many other threads, my gearlever P is supposed to light up red when it's in park, it's not doing that. I can hear a solenoid click when I put it in P though.

 

The car does need to be in P or N to enable cranking. Try starting in N.

The solenoid clicking you hear is more likely the Solenoid that releases the gear lever to move out of park when you press the brake pedal. That is a different sub system and is controlled by a different micro switch (the Not in Park switch). Nothing to do with starting the car.

 

The shift lever lock solenoid click is with brake switch

The key lock solenoid should be by moving the shift lever slightly out of the park gate ( not in park switch )

There are a couple of battery cable connections through the car to check , if compromised . it would limit the current to read voltages and operate things properly

" My XJR (x300) has always had weird voltage issues since I got it, if you put the heater or lights on you can notice the voltage drop at the dash gauge for example."

is an example

 

I hear the click down at the steering column but it could be coming from the brake pedal area, I don't recall hearing a click when I press the brake pedal though I'll need to check again in the morning.

I've removed the copper nuts and washers from the 3 terminals on the bulkhead and cleaned them then refitted and noticed no difference to the voltage issue. I only accessed the studs via the engine bay though, I've read a couple of threads stating you need to lift the carpet and get at the back of the studs too to check the insulators?

I think I might just scrap this car, not sure I can be bothered with it much longer. Shame as it has the makings of a good XJR and i've just put £1500 into it in just parts to get through the MOT.

 

The click from the brake switch controlled / shift lever lock solenoid would be in the shift box area , You can place your finger on the area of interest being the shift box / gates , relay and fuse involved

The brake switch is 2 switches in 1 package , 1 /2 only used for brake light

In cinching the battery cable connections behind the sheet metal . if you place 3 nuts on the treads and have the 2 outer nuts tightened to each other you can crank on the 3rd inner nut on the exposed side holding the 2 outer nuts / treaded shaft from spinning . This would tighten the cable connection behind the sheet metal

This is quick and easy to do before giving up

 

I'll check it again in the morning, I'm at my wits end.

I thought it would be the bulkhead connectors but typically it wasn't as simple as that. Then I read on another thread that the P should be lit up red, as should the N on the J-Gate, I don't recall if these lit up on my car before the no crank/no start issue but they don't light up at the moment.

Thanks again for helping Parker, you came to my assistance last time I'd an issue.

 

Patients after a break

The shift box lights can be squirrely to follow as a wiring guide understanding

 

Alright I couldn't wait any longer, I went out to the car there (it's 1am, the nightbours will question my sanity) and jiggled the gearshift about. I can get it to illuminate in the Neutral position if I hold it to the side but the car still won't crank over. Am I right in thinking it should crank in Neutral aswell as Park? I can't get the P to illuminate no matter where I jiggle the gearstick.

 

The not in park switch in the park gate has been replaced before with the wrong switch , normal open vs normal closed switch

The click by finger feel on the ignition key barrel lets you know the not in park switch is making , it doesn't tell you if the switch is correct

There is a linier position switch under the shift gate panel / cover that can get fluids into it and has been subject of a parts replacement / TSB / part # change

It can be opened up as the large switch black rectangle and contacts cleaned with a pencil eraser




The not in park switch has the wire pigtail

The linier position switch is the large black rectangle box on the same shift post right side

notice the 2 blue stripe relays , 2 solenoid relays . key barrel and separate shift gate lock

If you make the not in oark switch you will feel by finger the X side relay close , key barrel solenoid relay

 

Bed time

 

There is one large battery cable terminal post with mega fuse ( probably not blown ) under the rear seat as you have to remove the bottom seat pan , this is different than the fuse box area by the rear passengers ankles

Everything car fwd goes through this battery connection , the rear trunk fuse box is powered by a cable that goes aft from the battery

Your body processor module ( starter enables ) is powered by the trunk fuse box , fuse # 3 or # 4 , and goes back fwd to the glovebox BPM location

The terminal nuts may come loose limiting your current

It is some work to get to and is the last battery connection to check , has been loose from reading others

Be carefully of dragging the seat pan out the door , wears the felt liner door trim on the bottom

Also if you look at the positive battery post there is 2 mega fuses with terminal nuts that can have come loose

Do not over tighten the battery positive post as the curved nut underneath can split in half



It will be under the black triangle cover

 

Hi Parker,

I was speaking to another guy on the XJR owners forum and he said to check the switch at the J-Gate as to why it's not lighting up. I took it apart today and couldnt see anything glaringly obvious. When I was putting J gate back over the 4 screw holes that hold it there it let out a spark from underneeth it. Since then I don't get ANY lights on the J-Gate and now theres a light on the dash that wasn't there before - A gearbox light top left.

To say i'm struggling with the electrics on this car is an understatment.

I'll go and take a look at the megafuse and terminals after dinner. Thanks again!

 

Video 1: https://imgur.com/4XCTBop
Video 2: https://imgur.com/vLh0Ubr

The spark came from under the bulb here:


Here's the kind of battery drain I have, this is the hazard lights and then i put the headlights on (Bonus pic of the gearbox light in the top corner)
Video: https://imgur.com/u5vFaAH

(Tired embedding the videos and couldn't)

 

Video links works

I see the voltage sag

Probably need to resolve voltage issue first and things may come alive ( and some go away )

Videos with ignition key in the run position and not starting / cranking position ?

Need to do a fuse box each fuse check after the spark , but then again a fuse may not have blown

There is one transmission fuse that is sneaky as to where it comes from , but they are all in the boxes

The new battery can be bad and the auto parts store should test it , this more correlates to the issues not accuring until battery change, don't install battery in backwards

I've done that................................twice

This keeps you from removing rear seat pan

 

Yeah the key was in position 1, not two.

The amount of fuses and relays in this car is insane, I've never seen anything like it.