Hi everyone, I have an ongoing problem with my X300 1996 UK spec 3.2 auto.

Basically it just won’t start properly.

here’s where I am at:

1. the battery drains flat after a few days. If I try to start after a day or so the “check engine” light doesn’t stay on at initial ignition and nothing happens. Voltage at 11 volts. It then needs a fully charged battery, as well as a jump pack, and also a battery charger connected to get the voltage over 14.4v in order for the “CEL” (my abbreviation) to stay on. When that happens it starts, and then keeps starting with the CEL remaining on.
2. I have a replacement Secondhand security module in the boot, with a matched key. This seems to work better than my original key, but I still have the CEL problem.
3. the alarm fobs don’t work anymore.
4. The fuse at the engine bay fusebox for the ecu is showing the same voltage as the battery.
5. I have bought another ecu from XJRengineer, which is a North American spec and immobiliser deleted on it, but this has the CEL going out on ignition issue with a fully charged battery. If I switch ECUs the CEL stays on, switch back to the NA one and it is off. ER showing on climate module and bleeping.
6. I’ve bought 3 batteries in 10 months, this latest one is 3 weeks old and hasn’t been allowed to discharge. I removed the negative terminal, went back after a few weeks, and the CEL was on when on ignition.
Just to clarify: on all these steps, CEL off at ignition was always no crank or start, CEL on was crank and start no issues .

I’ve checked ecu connections all are good, no corrosion. Checked battery at various points. Levels of voltage all ok.

if anyone can shed some light on this complicated mess please please please help!

Thank you , Darren

 

Never install battery in backwards , positive post fwd , mark with tape and marker arrow

Never over tighten the battery positive post bolt , breaks curved nut underweight

For battery going flat overnight rotate the large switch on the steering column from auto to off , see how that works out

This allows hopefully for the security system to go to sleep and not drain the battery , or you can remove the fuse X in the trunk , the car will not start until fuse reinstalled

The security module and FOBs come in 2 frequencies 315 and later 433 hz and can get a clue by the rear windshield even though the windshield when installed may not be the correct one

What is your VIN # to know if in the 315 or 433 group

With your British model it has chip in key exciter coil in the ignition switch area but Andy may have deleted it in the Engine ECU as it sums up the valids / enables

For some joy and starter rotating you can take socket Y to a ground ( the valve cover is not a good ground ) to close the starter solenoid relay , there is a fuse # 3 / 25 amp left engine bay fuse box and fuse # Z right engine bay fuse box

Take the inertia / crash switch connector off and jumper with a paper clip between the 2 white wires

 

It’s SAJJFALG3BP791804.

I’m not sure which switch you mean on the column? is it a lighting switch?

I forgot to mention - I disconnected the ignition switch to see if it had a drain - still drained with the switch disconnected.

 

pulling up a video that shows the collum large switch and will be going to bed

There is a full car electrical distribution control test to perform with the ignition switch reconnected

With this connected when you remove key there is a linier switch from pin 4 to 5 ( car frame ground ) that starts a security system sequence of locking things up and only when satisfied ( agreements ) will the SLCM go to sleep

 

Thank you, sorry didn’t see the rest of your original post - it stopped at the vin number part on my screen.

I’ll have a look at these areas you have pointed out. Thank you

 

See minute 7 in the security section

 

Bed time in the States

Ask Questions

On your 3.2 liter model with a slightly different transmission ( ZF4HP 22 ) you will not have a transmission mounted rotary position switch ( in the starter circuit ) like the more common 4.0 literZF4HP 24

 

You need to sort out your parasitic drain issue first. Do the testing to identify the problem - loads of stuff on youtube and elsewhere to help with that. I suspect sorting that out may make the starting issue go away.


Also, testing voltage at different points (depending on how you are doing it) isn't a good method of identifying circuit issues. Basically, 12v can be seen with a voltmeter across a high resistance circuit - but as soon as some load is put on that circuit it can drop dramatically.

Search on You Tube for "Circuit Load Test" and "Voltage Drop Testing" for some techniques to help identify where you are losing your voltage.

 

You can take the small relay in the corner of the left engine bay fuse box ( relay only controls the car horns ) and swap with the right engine bay fuse box , the right must close to power the fuse for the ECU and the " control " power fuse Z ( Z is either 10 , 12 , 14 , or 16 ) " sitting on " to close the starter solenoid relay

The starter solenoid relay gets a ground to close by a ground provided by the body processor module after it sums up the starter agreements / enables ( transmission position in your 3.2 by the shift lever linier switch , security , key position , engine ECU )

Can't remember until researching if not in park switch involved , it is involved in ignition key barrel lock , the transmission position linier switch is the long black box to the right of the shift lever , you don't have to open this area yet but.....................






So the BPM ( fuse B in trunk ) is the heart ( sumizer ) of the starter system

The chip in key feeds the SLCM which in turn feeds the engine ECU which Andy modified

 

When reinstalling the SLCM ensure the battery is disconnected and may have to do a hard reset to get the SLCM and BPM to zero logic step to start from the " ground up"

The engine ECU does not have a hard reset

 

See post #5 in this thread https://www.jaguarforums.com/forum/x...-things-89335/

This is just one possibility.
In summary Steve Sparrow has described a similar problem that he had on the jag lovers forum.
As Parker has mentioned, in addition to rotating, the ignition switch has a set of contacts that connect when the key is just inserted and not turned.
When the key is removed this starts a shut down sequence.
If the switch is faulty and continuously makes contact when the key is removed the ECU thinks the car is still running - the battery will be drained and the key fobs won't work.
Removing a battery lead forces the shut down - hence apparently normal operation after doing so and as the battery is disconnected it cant be drained.
It is not an obvious fault but easy to check. There is more detail in the post.

As Brendan (b1mcp) has said you could also have a parasitic drain and if so you should sort that out first.

 

Thank you everyone for so many helpful replies.

So as recommended I’m going to move away from the starting problem and over to the drain issue which at least will give me some insight. I have already removed the plug from the switch and it does still drain without the switch connected.

but before I go onto the battery drain , just a couple of other things I have to note about the car..

1. When new (immob free) ecu is plugged in - On ignition the centre console bleeps 10 times, and shows Er on the screen, CEL not illuminating at ignition -no Crank or Start

2. When the other ecu is plugged in it doesn’t do this and CEL stays on at ignition level, Cranks and Starts.

I do need to get the immobiliser removed ecu working as the original security ecu doesn’t seem to work, and I’m using a borrowed set from another car.

 

the termed parasitic battery drain and key removal are related as a good charged up base to operate from

Nobody likes to start the day on a dead battery

The pin 4 to 5 making can be lubed with a graphite spray in the barrel but a dripping mess on your leg , don't try to make sense of the other pin positions ( 1 , 2 , 3 ) through to car frame ground yet , not the most confidence building

This pin 4 to 5 lets the SLCM know to start the lock up sequence before going to sleep least stay awake draining battery

pin 5 ( black wire ) on the car side of the connector should have as close to 0 resistance to car frame ground with a meter , same for the switch side pin 4 to 5 on key removal changing from open to closed or vice versa ( at least a solid / full change )

To remove the car side connector out to you just lift straight up on the dash mount

Large switch in the video rotated to off ? this removes both seat and steering collum from having to be retracted to exiting position satisfying / agreement for the SLCU that things are squared up to go to sleep , it will still look at door lock positions and trunk before going to sleep ( there is a wire loom on the cars right under cover trunk hinge that the wires rub exposing bare wire for trunk boot )

Do your have a driver door lock key barrel and a passenger door lock key barrel as some X300s came with both and the SLCM you acquired may not match the 1 or 2 key barrel configuration ( there is an agreement switch with the door key barrels so that can be lubed also but the switch may be external to the barrels , that I can't recall while mine was apart )

 

1. When new (immob free) ecu is plugged in - On ignition the centre console bleeps 10 times, and shows Er on the screen.
This is the climate control reporting that it has errors and that climate error codes have been stored.
The individual modules are all linked and communicate via a data bus.
I can't say for certain if the codes are stored in the ECU, in the climate control panel itself or in the climate control module.
The fact that error codes are identified with one ECU but not another makes me think they are stored in the ECU.
If this is the case then the replacement ECU has codes stored while the original ECU does not.
Anyway, when the climate control beeps and displays Er on ignition on you should run a climate control self test and identify and clear the errors.
The procedure to test, identify and reset the codes is described in the workshop manual section 14 pages 17-18 - Climate Control Systems 14.11 System Self Test.

As far as I know the normal operation is for all warning lights to illuminate on ignition on and then go out leaving the CEL on.
If the CEL is not illuminated the car will not start.
I don't know what XJRengineer does to remove immobilsation so I don't know if you should expect a CEL light at the end of the sequence with one of his modified ECUs.
In any event XJRengineer is undoubtedly the expert in this area and I suggest that you should contact him for advice.
It seems to me that if the car starts and runs normally with one ECU but not with another that the fault is likely to be with the ECU or the immediate connections.

Do you have 3 ECUs?
1. The original ECU - the car does not start with this.
2. An ECU with the immobilser removed by XJRengineer - the car does not start with this either and you have climate control errors (could be stored in the ECU and need cleared).
3. A borrowed ECU - the car starts and runs normally with this.

Just to be clear - we are talking about swapping ECUs making a difference here and not the Security and Locking Control Module located near the fuel filler neck in the boot?

 

Thank you for all the replies, I am reading them all, I have a plan to get back early tomorrow to work on the car some more. And thanks for clearing up the bleeping - I can sort that out.

I have three engine main ECUs -
1. The original one - which currently works - CEL on - car starts
2. The second one - borrowed from a friends car - this currently works as well - CEL on - car starts
3. The immobiliser delete one - this has the CEL off and won’t crank or start.

if I switch these ecus around - and I’ve touched nothing else - they will always act in the same way (CEL off or on and starting as described above).

The security ECU is from a separate car - I bought it from someone breaking one up. This comes with a matching key. But unfortunately not the key for the car - and only one anyway. This starts the car.

there is a security ECU and matching original key from the car which did start it originally - but now seems to have stopped working.

Because I was working on an assumption that there is an immobiliser issue - I wanted the ecu from XJRengineer to remove the whole immobiliser situation from the equation and move me forward with the fault finding.

But now I can’t seem to get that one to work - which if it does, I can go back to using the original key to start the car - and then presumably it will start every time and I can then continue with the fault finding.

I’m wondering if the ECUs in general go into a “low battery state” if subjected to a low voltage and then refuse to respond to a higher voltage unless it’s at a significantly higher level than normal.

the original ECU had this issue before - and wouldn’t respond until it had been given 14v - then just behaved normally. I’m wondering if this is a thing that does happen - and has happened to the replacement ecu. And if it does what are the voltages that would normally cause this? My jump pack and battery is running at 13.5v - easily enough to start the original ECU and the borrowed one if they are not in this weird CEL light mode.


I’m going to attempt tomorrow to get the replacement ECU running the car - and then check the voltage at the plug going into the ECU, and see if it is lower than the battery voltage.

I’ve still got the current drain to sort out, and I have a replacement BCM to try next - but I need to get the car at least firing up with the replacement ecu before I touch anything else in the chain.

thanks to everyone for your detailed technical replies, they are absolutely invaluable and I couldn’t even think of doing this without you all.



PS: just a back story - family members car, lots of memories attached. The car was driving and running for years. Battery then went flat - new battery fitted. Then this went flat. Then the car wouldn’t start even with battery charged.
At this point car came to me, I fitted a new battery, fired up and was fine. Then randomly wouldn’t start (same CEL issue). Battery started dying. Would start on a jump pack and a jump start (at the same time). Battery would charge then go flat. Then wouldn’t start at all. I changed security module and key chip. In December I needed to move the car, I used a jump pack, on charge, with a battery charger and it managed to start - it then started up for 3 days. I drove the car for 40 miles. Parked back home and left for 5 days - battery then flat - no start same issue.

3 weeks later I bought another brand new battery and put it on and the car started instantly. I ran the car for 20 minutes, and then turned it off and disconnected the battery. Then I arrived at this current situation this weekend just gone.

 

just to clarify something here..

so I understand the pulling the key out and it puts it to sleep. Does that actually have to connect pin 4 to ground in order to sleep the SLCM? If that is the case - if I disconnect the plug will that mean that pin 4 is still not connected to ground and then the SLCM won’t shutdown?

I’ve tested this plug operation by unplugging it and leaving it for a few days to see if the battery still goes flat - which it does. I’m thinking if this needs a ground connection then this is not the way to test it

 

I never determined on mine if the 4 to 5 goes open it will start the lockdown sequence or if the 4 to 5 goes closed

this has to go through to the pin 5 car frame ground on the car side connector half so yes must be connected and there are problems that can exist on the car side pin 5 black wire

Once the SLCM gets this " trigger " it will take some 20 seconds if it gets all of it's agreements ( seat and steering collum position sensors arriving ( which you can negate by the large switch to off ) , door and trunk locks position sensors , then go to sleep

The battery drain will be about 20 milliamps at the trunk fuse if gone to sleep , this can only be tested with trunk closed ( long wire meter leads ) , aftermarket stereo heads will affect this and be higher than the 20

There is a whole car electrical distribution test if a king relay in the corner of the fuse boxes stick closed draining your battery

You may have to reconnect the original SLCM and BCM ( BPM ) as you may have squired it's brain on removing the connectors ( 4 ) with battery still connected

disconnect and reconnect with battery cable off for both SLCM and BCM ( the heart of your starter rotation circuit )

After reconnecting may have to do a hard reset of the SLCM and BCM to get back to 0 logic step

A hard reset is more than a positive battery cable off

There is a large connector ( called BT - 4 ) above the fuel tank to ensure the tie - wrap is on it securing it closed , do not remove connector yet

Your asking the right questions , and yea new batteries are garbage these days in the states so that never helps

The climate control self test with codes can be found on page 110

T703 BOOK

Short printable pages here :

14-10

 

With respect, you need to stop pissing about changing modules and stuff and work on diagnosing the issue. Why have you ordered a new BCM? You risk introducing new issues and compounding the problem with unknown parts.

Only replace a part/module if you have diagnosed it as faulty and you know why it is faulty – then you can test the replacement to confirm it does not do the same. Don’t guess.



Go back to base. Put the original ECU (that you say starts the car) and go from there. Your assumption is (as per thread title) that you have an ECU issue. Have you got some diagnostic data that shows that?



Fully charge your battery. Connect an amp clamp (recommend Fluke 325 if budget allows) or your DVOM on amps in series with battery ground lead. See what it says – likely shows a current draw with everything off and car locked.



Now start unplugging things one at a time until the current draw stops. It may be quite revealing!



Also, you can get a budget diagnostic tool (Autel AP200 about £45) that can show live data from BPM that includes whether the ignition “key in barrel” is active or not – aswell as other useful things. May be a good investment.

 

There is a process of removing the battery cable terminal post ( 13 mm ) on each fuse box one at a time to locate battery drain

Starting with the trunk fuse box terminal as this is your SLCM fuse and even for the BCM fuse to feed up front behind the glove box

You can observe the voltage drain over time with a common cheaper ( digital easier to read in this case ) meter as Flukes are not cheap

Noting that after a charge up either by alternator turning or charging device you can see an over voltage value until the battery comes to it's own equilibrium


Once saw I think 13.07 volts until it settles down to 12.75 as your time to begin measuring at 12.75

This can shorten your overnight battery state observations , but a hard reset does take overnight / no shortcuts

 

I do need to stop pissing about changing everything.. I wouldn’t normally do this, it’s just so complicated, and it has been just guess work.

Tomorrow I’ll go back to basics. I’ll test everything as you have said - multimeter in hand, and get some better idea as to what is going on.