For my 1996 VdP, been running like a bird. Suddenly the doorlocks don't respond to key fob or dash switches, and although the dash lights up with the key, nothing happens when I turn it to Start. Battery is good. I am presently guessing that the Security Module has failed, but hopefully there's an easier explanation?

 

The fuse for the SLCM is either # 3 or 4 in the trunk

Just above the fuel tank is a large connector that should have a tie wrap holding the lock over bar on it

To put the connector back on can be a pain least breaking the lock over bar external lock pins

Here in the USA models there is a reset of the SLCM and BPM ( starter enable )

Rain water in the fuel cap well ? This lets water on the SLCM connectors under it , mounted at a slight angle with 4 connectors on it that look like 1 as they are butted against each other

 

Parker - your post looks enormously knowledgeable and helpful, many thanks, but I'd appreciate a few more words to help my understanding.
I'm assuming that the connector you show is situated in the left side of the trunk, and that you are suggesting that it be inspected and opened and closed a few times with the possibility of contact corrosion due to fuel filler recess leaks?
And what does "Here in the USA models there is a reset of the SLCM and BPM ( starter enable )" mean? Does that mean there is an automatic reset when you pull the connector, or what?
With best regards.

 

The SLCM is under the fuel cap well / lid on the cars left

It should only be disconnected with the battery positive post terminal removed , same as connecting the SLCM

This is the 4 connectors ( looks like 1 )on the SLCM that are subject to water from the fuel cap well

Do not over tighten the battery positive post bolt < breaks the special nut underneath

The pictured connector is by removing the trunk liner on the fwd panel

Inspect for the tie wrap before removing the connector as can be a pain to reconnect

The hard reset will knock out your stereo head theft protection , but this does not accure on North American market models

The hard reset is removing both battery cables and joining them together above a towel insulating the battery both posts

The longer the better like overnight , but you can get results with a short time joining

You can use a battery jumper cable to join the 2 battery cables

This will not effect the engine regulation like on some other cars

Ask questions

 

Parker - I pulled the back and side covers off in the trunk but no sign of any connector there. Perhaps it's below the trunk floor, down where the spare lives?

 

Should be above the car's left fuel tank's left edge

Might be outboard of the trunk left hinge as it must install upright , but at a slight angle

The connectors enter the module from the car's right so there is alot of wires / bundle

 

Finally got this sorted. I found the module where you said, tucked hard against the inside of the wheel well to the left of the tank. Could not see the big connector you mention, that must be further in, but also no sign of any leaks that could cause problems.
The symptoms in the end were that the security system would either disconnect completely, which meant that the electric locking and starter were non responsive, or would reconnect and start the alarm and allow the car to be started. Possibly due to an intermittant connection in the connectors at the module, or in the module itself, but permanently fixed by replacing the security module.