Another Central Locking Issue - Help!

[daveo138]

Originally Posted by BigRuss

It's an alarm sounder with a battery backup, it's usually fitted if the car has headlamp washers

Both are connected to the same relay in the Body control unit.

Russ

I don’t have headlamp washers, so I guess not.

[SD1too]

Originally Posted by daveo138

I don’t have headlamp washers, so I guess not.

Hi Dave,

If your car's alarm sounds like a normal horn pulsing on and off (and indeed it is a normal horn, mounted in the plenum beside the ECM) then you don't have a BBUS.

Originally Posted by BigRuss

As soon as the ignition is switched on it will no longer lock on the remote after switching off and removing the key.

This can be caused because the immobiliser is unable to check the locking state of the car usually because one of the immobiliser power feeds is missing.
...
Try Fuse 36 (5A) for the immobiliser and see if that's blown or dirty (the later micro fuse blades get a build up of deposits on them )

I think you should next pursue this idea from Russ. Quote from RAVE:

"When the doors are locked or unlocked, the BCU will transmit a K-bus message to update the status of the vehicle locking system, doors, bot, bonnet and windows."

Fuse 36 is in the direct battery feed to the immobiliser's logic circuits which will communicate with the BCU on the K-bus.

Simon

[Onesixty]

Hi guys, sorry to piggyback this thread but I have the exact same symptoms and do have the BBUS and headlight washers (although they are not currently connected).
I’ve also tried a new (known, working) door motor connected in the car and again still no joy.
Interestingly I had removed the fuse for the sounder as it was constantly going off irrespective of the car being on/off locked/unlocked.

Where is the bbus located please? I’ll try and disconnect it and see what happens.

[SD1too]

Originally Posted by Onesixty

Where is the bbus located please?

In the plenum chamber Ben, next to the ECM. Note that it has its own integral battery.

Simon

[daveo138]

Originally Posted by SD1too

Hi Dave,

If your car's alarm sounds like a normal horn pulsing on and off (and indeed it is a normal horn, mounted in the plenum beside the ECM) then you don't have a BBUS.

I think you should next pursue this idea from Russ. Quote from RAVE:

"When the doors are locked or unlocked, the BCU will transmit a K-bus message to update the status of the vehicle locking system, doors, bot, bonnet and windows."

Fuse 36 is in the direct battery feed to the immobiliser's logic circuits which will communicate with the BCU on the K-bus.

Simon

Hi Simon

I did clean & test all fuses yesterday. No joy. (Post #16)

Unless it’s a dodgy connection at the other end - immobiliser or BCU?

[SD1too]

We're in danger of a recurrent guessing game here! Let's go back to what you were told when you bought the car:

Originally Posted by daveo138

"The central looking unlocks fine on the button but doesn’t lock remotely unless you first pull and then reinstate fuse 32 ..."

Fuse 32 is the battery supply (C0660-54) to the BCU logic circuits. The fact that the fault condition is reliably corrected by reseating this fuse suggests that it's not a poor electrical connection (which would be random and unpredictable) but a communication error which is reset by effectively rebooting the BCU.

The driver's door lock sends a "locked" and "unlocked" signal to the BCU from two microswitches (contacts normally open) along separate wires (KN & KW). These are included in connector C0660 which is in the middle position of three black connectors. It has 54 pins in three rows. Try reseating it.

[Fuse 8 is mentioned (post 2). This appears to be in a +12v engine cranking signal between immobiliser and instrument pack so is unlikely to be responsible. Likewise for fuse 15 which is a battery supply to the instrument pack.]

Simon

[Lagetha]

I've found with my 2000 1.8 75 that locking the car twice manually activates the dead-locking feature and arms the alarm! That is turn the key towards the rear of the car, return it to the centre position, then turn it rearwards once again.

[daveo138]

Originally Posted by SD1too

The driver's door lock sends a "locked" and "unlocked" signal to the BCU from two microswitches (contacts normally open) along separate wires (KN & KW). These are included in connector C0660 which is in the middle position of three black connectors. It has 54 pins in three rows. Try reseating it.


Simon

OK, I've reseated the connector, but there's no change in symptoms.

Judging by the sticker on the BCU, it's been replaced at some point.

[SD1too]

Originally Posted by daveo138

OK, I've reseated the connector, but there's no change in symptoms.

Thank you Dave. It's always worth trying the basics before diving in at the deep end. I'm thinking that you need the assistance of T4 with this one. You're about mid-way between Russ in Leeds and Jamie near Cannock.

Simon

[daveo138]

Thanks Simon.

I might have to have a chat with Russ. A run up the M1 wouldn’t be too bad.