Central Locking - Again

[ericmc]

When I acquired my May 2000 V8 the central locking didn't work. Using the key or the remote it locked and unlocked immediately. I know there is tons written on this subject and I came to the conclusion that problem was caused by the front passenger door actuator because I didn't see the locking lever move when attempting to lock. Moreover, if I pressed it manually the doors would all lock and then if I tried to unlock it would unlock and lock itself again.

I never noticed if the rear doors' levers moved during this procedure but I'm sure I could individually lock all the doors by hand. Before I could change the actuator the fault changed so that now none of the locking levers except the driver's door can be moved by hand. They are not jammed but they can't be pressed in to lock and now the only door that locks momentarily is the driver's.
The front passenger door and the two rear doors are all controlled by signals coming from the Rear Electronic Control Module which in turn receives its command via SCP from the Driver Door Control Module.

Has anyone come across this problem and know how to cure it?

Eric

[oldtimer]

Eric,
I hardly dare add to this. As you say there is a huge amount written on the subject. Martec is the main man on this topic.
So often the finger is pointed at the Battery which I am unable to comment on but would ask you to check something for me. I suppose we normally get in or out of the car with the engine NOT running therefore we are relying on the Battery to do the necessary.

If possible, could you please start the engine ,run it at say 1500 rpm and then function the door lock mechanism. The reason I ask is that the Alternator should be charging and raise the system voltage. I am told that electronics are voltage sensitive.

I too have had a couple of melody's with door locks and then vanished

Oldtimer

[J44EAG]

I`ve had this occasionally.

Removing the door card, pulling the wiring plug apart and refitting and also ensuring the lever rods on the actuator to the lock mechanism are not semi-seized can sometimes fix the issue. Full and free movement...or lack of it, can sometimes cause these issues.

I recall the door lock module is located in the drivers door with the plug onto the unit also a possible electrical hot spot issue. removing and refitting again my prove beneficial.

Very early cars were prone to actuator issues on a regular basis. Hopefully that came up for review and modification as we have notd hear quite so much about the problem in recent times.

Mike

[ericmc]

Oldtimer, thank you for the battery suggestion. I measured the battery terminal voltage and found only 11.66 volts. I have done a lot of short journeys recently so I put the charger on for a few hours and got the voltage up to a more reasonable 12.7 volts. Unfortunately this made no difference to the problem. I also tried running the engine and operating the driver door lock manually ( the remote is inhibited with the engine running). It still didn't actuate any of the other locks.
While the battery was charging I discovered that the two rear locks could be moved with some pressure and so I think you are right Mike, they need freeing off because they are too tight. Still couldn't shift the front passenger lock so a separate problem to resolve there but the underlying fault seems to be that the RECM is not sending lock/unlock signals to the three doors that it controls.
The wiring diagram I am using is for the 2001MY and it may be the 2000MY (mine) is different because it shows the SCP control signal from the DDCM passing through a secondary junction box which should be located on the LH side of the bulkhead in front of the A post. I can't find it there which is frustrating because I thought that would be a good place to scope the control signals.
Have run out of time today but will try to get back to it tomorrow.

Eric

[oldtimer]

Hi Mike,
I don't want to get embroiled in this subject at the moment cos the car is in bits on another job.

However, the door lock system mystifies me in that none of the defects are consistent. For example, the off side rear door fails to lock or un- lock then it does. I've been locked in, opened the drivers window only to find the external handle doesn't open the doors, but the dash board switch opens all doors and so it goes on. I've had a new off side rear door lock on the bench for months - then it started to work again

One day I will have to give it a serious looking at !

P

[J44EAG]

Very inconsistent symptoms indeed over the years.

Similar with reverse sensors. They can be ok for ages, then start playing up for no apparent reason. Then they sort themselves out and function correctly again. certainly never had any similar gremlins with a 93 BMW 530, but I suppose it was rather less sophisticated.

One hopes later Jaguar models are not as troublesome.

Mike

[Martec]

Hi Eric,

This subject has been done to death on here and in the magazine.

I have a 2000 car and use the wiring diagrams for 1999 - 2000 from this free site http://www.jagrepair.com/JaguarSTypeEle ... Icodes.htm along with other free manuals.

The workshop manual for 2000 I had to buy online at the exorbitant cost of £5 odd.

Apparently Jaguar had complaints that the solenoid locks made a very loud noise in early morning starts so changed them to motors and used small sub-micro switches, unfortunately one switch in particular was used as a swipe rather than a press switch which is what it was designed to do, and so it fails early and causes most of the problems of staying locked or in my case staying unlocked.

Mechanically they are very robust but the levers on the back of the lock corrode and get stiff, and I've not managed to get an oil can to them in the back doors (very difficult to get access to), the passenger front door is easy, but the drivers door lock is shielded to stop thieves and is awkward to get out.

I checked the wiring using the diagram but didn't find any breaks in it, the down side to the diagram is that it is drawn for a LHD car, but this is not a problem if you follow the wire colours to the appropriate terminal plug in the rear electronic control unit (some positions are reversed for RHD).

Best of luck.

Brian

[ericmc]

If anyone is still interested in this topic, I have managed to repair a couple of door lock actuators and found out a great deal about how they work. I have written it up, with pictures and put it on my website. (I couldn't figure out how to post it here. The photos seem to be a problem). This is the link to the S Type section of my site http://www.stretton.tv/s_type.htm where you will find a button for the actuators.

Eric