Central Locking & Electric Windows 92 E36 Coupe

[wrs 120]

Hi All,

In the last few days I started having issues with the passenger door not unlocking with the drivers door but the boot and petrol flap still unlocked. Then yesterday only the drivers door would unlock and the boot and petrol flap stays locked. Today the electric windows won't wind down or up (may have not worked yesterday too but I didn't notice).

I don't think any fuses are blown for the electric windows because the passenger and drivers door window still drops automatically when the door is opened and closed so there is power.

I suspect there's some control box somewhere that manages all the doors and windows that's gone fut. Any ideas where to start looking?

 

Edited August 23, 2017 by wrs

[M3AN 4016]

TBH I have very few ideas but hate to see an E36 cry for help go unanswered... so here's my 2 cents worth...

Could be a bad ground but I doubt all of the above uses a single, common ground. Nevertheless, worth checking.

Some general electrical diagnostic advice here: http://www.pelicanparts.com/bmw/techarticles/101-Projects-82-Electrical-Problems/101-Projects-82-Electrical-Problems.htm

Final thing from me: the wiring loom that goes from the main body into the boot lid is notorious for causing weird and random electrical glitches in these cars... might pay to pull (or cut) the sleeve back (left hand boot hinge) and check for shorts there. See: https://www.bimmerforums.com/forum/showthread.php?79896-Attention-ALL-E36-owners-beware-WIRING-PROBLEM

Let us know how you get on.

 

[wrs 120]

Thanks for the info. I've been looking at the wiring diagrams and suspect it might be the drivers door lock switch. I recall the drivers door key being a bit difficult to turn a couple of days ago as well and it took a bit of extra force and then suddenly gave. I may have broken the locking pin to the locked/unlocked switch. If the door thinks it's permanently locked, from the wiring diagram it looks like the windows will be disabled. It also explains why the central locking won't work.

I'll have to pull the door lock out in the weekend. Will also check the boot wiring loom...

[wrs 120]

Problem Solved

It was the +12V red/green wire junction under the front passenger foot-well area. The glue holding in one of the bungs to the underside of the car had let go and the bung had popped in so water could get in when driving in wet weather. The whole area under the carpet was flooded and the +12V junction had one wire corroded off and signs of corrosion on 2 others. I cut the junction out, twisted the wires together and crimped them + covered in glue-lined heatshrink. Everything worked fine after that.

I then glued the bung back in with marine urethane. I've left the passenger seat out and the carpet up to dry out. I'll also be able to see if it still leaks when it rains - it's bound to rain this week sometime...

Of course, I only found this after taking the door apart first... The give-away was no 12V on any wire in the door. One wire had 1.6V on it - likely the corrosion conducting a tiny amount.

I also found broken wires in the boot loom and fixed these too but it wasn't the cause of the problem. I've seen a lot of instructions how to fix this any may say to cut the sheath covering the wires. You don't have to do this - it's silicone covered fibreglass sleeving and it bunched up really well. All you have to do is pop the bung out of the boot end, unclip the sheath from all the plastic clips on the boot mechanism and slide the sheath down so it's all bunched up at the car end of the loom. That way you keep it intact and waterproof.

Edited September 21, 2017 by wrs

[wrs 120]

Update:

We finally got some rain yesterday and I still have a leak. It's coming from the heater seal. I checked the scuttle drain and this was mostly blocked with only a very slow drip. It's now unblocked and flows freely but when I slowly pour water into the scuttle bay there is still a leak into the cabin from the heater. It's a big leak on the passenger side (left) and very small on the drivers side (right).

This means the seal from the scuttle bay round the heater has failed - bugger!!!

I really don't want to have to take the dash out - is there any other option to fix the seal? Can I poo some sealant round the heater?

However, I'm already half-way there as I took the carpet out yesterday so I could see where any leak(s) were coming from. So far it looks like just the heater. To get the carpet out I had to remove everything except the dash... With the carpet out I found quite a lot more surface rust + the black goo was delaminating off the painted steel with water trapped behind it. I removed the black stuff and dried everything out. Will rust-kill before the carpet goes back in. The old carpet was still quite saoked in a lot of places even though I'd had it lifted for the last week and a half. Since I have a new carpet to fit I mostly cut the old carpet out.

If I take the dash and heater out to replace the heater seal (and o-rings) is there anything else recommended to do - was going to lube the fan bearings as they've been squeaking after about 30 minutes operation for several years now. Maybe replace the filter too? My aircon died a few years back too so that's already degassed (degassed itself when the compressor blew + removed all the front radiator, compressor + filter etc when doing the engine swap - it was a lot of weight!!). It will also allow much easier access to replace the carpet (got a second hand carpet in much better condition to put back in - no mould, is not smelly and is already dry).

[wrs 120]

Today I ordered the new seal from BMW - 2 weeks ex Germany $85.

I've also found a second hand heater unit at the wreckers I'm going to take out on Saturday - good training for taking out my dash. Once I have the second-hand unit I'm going to take it apart to remove the heater core and air-con core. I'll replace the original heater core with 2 x 300W ceramic electric cores and make a PWM controller to regulate the power. I'll check the state of the motor bearing at the same time and hopefully only need to lube them a bit. With the carpet currently out of the car it will be easy to tap into the main 12V wire to the battery for a high-current power source for the heaters. It passes under the drivers footwell area with a good solid cover. It will be easy to cut the cable and join with a Utilux barrel-crimp with additional wires added, then hex-crimped with a hydraulic crimper. Two layers of glue-linded heatshrink should ensure the insulation never wears through + will make the join water-tight. Will need to check the alternator is good for 2 x 21.5A continuous. For the heater control I'm going to add voltage detection so the battery has to be over 13.4V before the heater can be active (car started and alternator charging)... I'll have to try to figure out how the temperature regulation works on the existing system and link this to the PWM control for variable power to the heaters.

My heater control valves failed a while ago and they're nasty to repair and very expensive to replace. I'll just loop the in-pipe to the out-pipe and remove the valve completely - won't be needed with the electric heaters. Going electric will also mean instant heat as soon as the engine is running. It also means I'll never have to worry about the heater core leaking in the future.

[wrs 120]

After looking at the Integrated Climate Regulation (IHKR) wiring diagram I can see changing to an electric heater is even easier than I'd thought. I can use the original water valve assembly control wires to switch the left and right electric heaters on and off. When switched on I'm going to use simple temperature control on the heater cores. The original water heater core would have run at around 90-95'C so I'll simply regulate the electric core to run at about 93'C using a thermistor & comparitor to switch a mosfet on and off - no need for PWM. Then the heat regulation should be fairly similar. I suspect the electric heater won't actually get up to 93'C very often as the airflow past it will likely keep it pretty cool. The original water heater core would be able to deliver much more than 300W to each side of the car...

I'll switch the main 12V supply to the heater cores with relays as well to give a double level of protection. Then I can add a second set of thermistors for over-temperature detection to switch off the relays - don't want a fire if anything goes wrong. The relays will also switch off with the ignition and the original water valve control.