My S2 coupe bit of a rebuild and repair thread.

[Bowie69]

Yes, knew there was s third switch!

[Tractor Dave]

Pretty sure I have a spare here if you want to swap it out

[B5NUT]

Pretty sure I have a spare here if you want to swap it out

Thanks for the offer Dave, I've just placed an order with tradition for a new brake reservoir, booster pressure sensor and PAS reservoir cap. I unplugged the connector going to the brake reservoir and so far no more errors. So I think we could have a winner however I will change all the sensors one by one over the course of a few weeks to make sure I know which one was the faulty sensor.

According to Etka, and to be fair on our cars it's not 100% accurate there is only a replacement sensor for the LHD tank. As I say not 100% sure if that is accurate or not.
sensor.jpg

[B5NUT]

So with possible fix for the bomb warning light coming on. I want to solve the final fault on the car! When I say final, I mean the only known fault on the car at this point in time

The last fault is with the central locking. When the car is unlocked the pump runs on for about 10-15 seconds. So far I have removed and checked the drivers door actuator, boot actuator and the fuel cover actuator non of them appear to have a leak.

I'm assuming the pump creates a pressure to unlock the car and a vacuum to lock the car. I don't have any issues with locking or unlocking the car and I get a beep when the car locks. Could this be a sensor issue with one of the locks or the pump it's self? Or do I just have a leak somewhere?

[steve briance]

Im watching with interest how you fix (there is no dount you will!) your central locking fault as i have exactly the same issue but not enough time to get it sorted. When it occurred, i did find mention that there is a microswitch in the drivers door locking mechanism which fails and, when it does; the system doesnt detect that it is locked and keeps going. Its either the switch or the plastic which presses on it thats snapped off. Maybe worth having a look in there if you currently have it apart to check actuators.

[newsh]

I don’t think it will be the little microswitch in the lock, this plugs in near the door lock with a 3 pin plug and can be tested with a multimeter from there. Middle pin is common and the other two are momentary. (I’ve changed two of these over the years, is it a PITA to do? Would I like to do another one?) This is the switch that detects you turning the key so it would seem it’s working.
I think the switch that reports the position of the actuator is part of the actuator in the bottom of the door. If it doesn’t report the door is locked the pump runs on till it times out.
It’s been a while since I looked in there but I’ve probably fixed most of these issues on one or other of the cars I’ve had, especially the coupe as it’s done over 300k now..

[Bowie69]

Yep, door lock actuator maladjustment, or microswitch failure. Sometimes the rod doesn't go far enough one way or the other to trigger the switch.

You can get them going again for a while, but better just to replace in my experience.

[B5NUT]

Thanks guy's. I did wonder if it could be a switch/sensor issue. I've put the door back together but it's easy enough to take apart.

If the microswitch has failed does anyone know if it's possible to repair them?

[Bowie69]

Sealed unit, plastic welded together.

They are cheap second hand on ebay, i buy the latest cabrio parts.

[B5NUT]

Well checked both actuators and they both appear to be working even swapped the out just in case and still have the same issue. Also checked the pipe around the door grommet and it looks OK no holes etc. Need to check the boot switch to see if that has an issue. Any other checks before I put the door cards back on?

Also found this old Motorola tracker fitted to the car, with a heavy little battery attached to it which was dead as it was only reading 0.6V . So it's all been removed and the harness fixed where they had tapped into it for power.
tracker.jpg battery.jpg

[newsh]

Pull the plug and just check the lock micro switches are working, middle pin common, other two pins momentary.
When you turn the key one way one contact will close.
When you turn the key the other way the other contact will close.
Let go of the key and both sides should be open circuit.
Check both doors.
You can test for a vacuum leak with a mightyvac.
It’s possible there’s a wire broken in the boot loom..

[B5NUT]

So using a meter on the middle pin and one of the side pins are active when the doors are unlocked and it stays active, and the opposite side pin becomes active when the doors are locked and again stays active. I've quickly looked a the loom going through the bellows on either side and it looks ok. I've also noticed It activates the pump to unlock as soon as the connector is plugged back into the activator (same for both sides). I've also swapped the activators out. So I can rule them out (I think).

I've had the boot apart again this afternoon and could not see any or hear any issues. I think the next port of call is the pump or a leak around the pump. They are usually well insulated so will have to take the rear trim out and have a good look around. Another option will be to pressurise the system and see if I can find a leak.

However on the plus side today I did find one more MOT issue, One of the bulbs in the number plate light had failed so replaced them both. I had completely forgotten about the number plate bulbs.

[B5NUT]

Well it's the day of the MOT and something weird has already happened to the car. Unlocked the car this morning to check fluid levels etc and the the central locking pump over run problem is fixed! Pump now only runs for a few seconds before it shuts off. I have no idea why it's now working and I don't like fixing faults like that but will take it as a win.

Don't think the fault has been an air leak, it's more likely a bad connection, so either a bad wire in the bellows that is now making contact or the contacts on the actuators now making good connection. If the fault comes back then I'll clean up all the connections (should have done that in the first place) and check all the wiring out.

[Tractor Dave]

Good luck with the mot. I'm sure it will pass with flying colours. I always get nervous despite having changed and refurbished absolutely everything. I don't know why.

[B5NUT]

Thanks Dave. I just hope the exhaust fix has worked. Not heard any metal on metal sounds but you never know. I'm also worried about electrical issues, like the brake switch etc and spurious fixes like the central locking now working. Could there any other wires not making good contact! O well I will know in just over an hour.