1995 540i heater valve problems

[Clarksonvalley]

I get the smell of something electrical overheating when the car is running - coming from the vicinity of the heater control valve and aux. heater pump. The cooling system is full of 50/50 antifreeze and has been fully bleed. I replaced the aux. heater pump thinking the motor was going bad, but the same smell still exists with the new pump. The aux. heater pump is getting 12.5 volts with the ignition on - this pump runs all the time the ignition is on and all the time the engine is running regardless of where the driver and passenger rotary heat control switches are set - this agrees with the heating system wiring diagrams. I get 12.5 volts at the heater control valve, but the voltage stays the same regardless of where the rotary heat control switch is set - this does not seem correct as the voltage should vary with the rotary switch position in order to open or close the heater control valve. Only when the driver rotary switch is fully rotated clockwise does the voltage to the heater control valve go to zero. Anyone had the same experience or have a solution?

Tom

[shogun]

the aux water pump does not run always, it starts only when heater is on and the coolant is above 30 degree Celsius and when heat is needed depending on the settings on the thumbwheels on the control panel.
It pumps 950 l/h. Here is a 53 pages tech info in German language how the system works
http://www.e38.org/e32/klimaautomatik.pdf
even if you do not understand, you can read the drawings, aux water pump control is in section 5.8

Maybe the control panel/module is defective.
IHKA pinout
http://www.bimmerboard.com/forums/posts/426626/
heater valve pinout
http://www.bimmerboard.com/forums/posts/841827/
wiring diagrams
E34 (1988 to 1995 5 Series) Wiring Diagrams (http://shark.armchair.mb.ca/~dave/BMW/e34/)

[Clarksonvalley]

As I look at the wiring diagrams, the aux. water pump relay coil gets power from fuse F29 which is' hot in run and start' and the water pump relay power contact gets power from fuse F9 which is 'hot at all times', so the aux. water pump appears to run at all times. This would make sense as the cabin temperature is regulated during the air conditioning mode by adding heat to the cooled airstream via the driver and passenger heater rotary switches. Wish you had an English version of http://www.e38.org/e32/klimaautomatik.pdf (http://api.viglink.com/api/click?format=go&key=9471fc9a94e73595983f2ab94f973065&loc=http%3A%2F%2Fwww.bimmernut.com%2Fforum%2Fnewre ply.php%3Fdo%3Dnewreply%26p%3D343050&v=1&libid=1351719592173&out=http%3A%2F%2Fwww.e38.org%2Fe32%2Fklimaautomati k.pdf&ref=http%3A%2F%2Fwww.bimmernut.com%2Fforum%2F5-series-bmw%2F44172-1995-540i-heater-valve-problems.html&title=1995%20540i%20heater%20valve%20problems%20-%20Reply%20to%20Topic&txt=http%3A%2F%2Fwww.e38.org%2Fe32%2Fklimaautomati k.pdf&jsonp=vglnk_jsonp_13517200815601).

Do the water control valves position themselves in response to a variable voltage from the rotary switches (do they actually vary the voltage as the switch is rotated) or do they oscilate between 100% open and 100% closed in a frequency to vary the water flow? And, where do you think I am getting the 'pending electrical fire smell' from - the aux. pump or and water control valves?

Tom

[shogun]

copy or retype the description of the aux water valve and put it into google translate. It clearly says that it only runs when heater is on and from a certain coolant temp., and that makes sense, because first the large coolant cyle is closed to heat up the engine, and only when engine operating temperature is reached, the large cooling cycle opens by thermostat opening and then the hot coolant comes to the heater valves. Small cooling cycle means engine only.
water control valves position themselves by variation of the voltage at thumbwheel, actually they pulse. Depedent on the temp adjusted and the water flow and temp sensors feedback, controlled by the IHKA control unit

[Clarksonvalley]

Yes, I thought of the Google translate - can't copy from a PDF and paste onto Google translate, so I'll do it the long way as you suggest and retype. Any thoughts to the source of the burning electrical smell I am getting from the underhood area around the aux. water pump and the heater control valve? Is there any way to use a volt meter to check for the proper signal from the driver and passenger rotary switches to the heater control valves? I get a constant 12.5 volts on the driver rotary switch until you rotate it all the way clockwise and then no voltage at that point. I get no voltage regardless where the passenger rotary switch is positioned with the driver rotary switch past its detent?

Tom

[Clarksonvalley]

Shogun - and thoughts on my last reply?

[632 Regal]

Tom, your passenger thumb wheel is fubar which is why you get no action. However the driver side should control both sides for the most part. Are any wires getting hot near the aux pump?

[Clarksonvalley]

Thanks for your reply. I've been away from the BMW problem rebuilding my wife's Miata engine. As I remember, I get 12 volts at the pump and nothing at the water valve. I understand the water valave gets a pulse voltage from the dash rotary switch, but I don't see anything. I'm going to try running just the aux. water pump and see if I smell the nasty electrical smell - it's a new pump. If that's OK, I connect the water valve and see if the smell appears. I may order a new water valve if the smell appears. If the pump and water valve are OK, I'd guess the problem is with the rotary heat switches in the passenger compartment. The rotary switch does not sound like an easy fix.

Tom

[shogun]

sorry, was on overseas trip and could not reply. Use a small spare bulb from brake light or so and solder to short wires on it with a crocodile clamp and then test the function of the thumbwheel.
Do not put the thumwheel on full heat over the small resistance, because then the heater valves do not get any power. Use the bulb on the heater valves and then turn the thumbwheel slowly up and down, then you should see the bulb pulsating. That is almost impossible to see with a digital voltmeter.
You can disassemble the rotary switch and test it, here is some info how to disassemble it

BMW E32 Climate Control Illumination (http://bmwe32.masscom.net/johan//IHKA_lights/IHKA_lights.html)
In the worst you can also buy a used control unit from the Bay, usually not very expensive.

But if you nasty electric smell, then it could mean that maybe some wires are shorted/blank somewhere.

[Clarksonvalley]

Shogun,

My 540i E34 does not have thumbwheels - it has rotary dial switches, one for the drivers side and one for the passenger side. As I understand the test with the light bulb, I would connect it in series with the water valve solenoids, not in parallel - correct? I'll also check for wiring shorts to ground - can't believe there will be any shorts or the whole thing would have burned down by now or at least blown a fuse.

Tom

[shogun]

connect the bulb between pin 1 and 2 and /or pin 1 and 3 of the heater valve. All wires connected = plug to the heater valve is plugged in, the bulb additionally.
When ignition and aircon is switched on, you can see on pin 1 12 volts. With this additional bulb between pin 1+2 or 1 and 3 you can now see if the control panel works.
3 pins, 1 x 12V and the other 2 for each valve is ground.
heater valves pinout Pictures, heater valves pinout Images, heater valves pinout Photos, heater valves pinout Videos - User Media - TinyPic - Free Image Hosting, Photo Sharing & Video Hosting (http://tinypic.com/usermedia.php?uo=TChd6DpwTVUtqzIx54bDlYh4l5k2TGxc)
Some more info from E32Fan, he is expert in electrics on E32 and also E34
Pin Outs Heater Valve and Aux Fan Switch - Bimmerforums - The Ultimate BMW Forum (http://forums.bimmerforums.com/forum/showthread.php?t=1817268)

[Clarksonvalley]

Shogun and all,

Here's what I get with my multimeter at the aux. water pump:

With engine running, 14.07 volts at aux. water pump, amp draw = 1.81 amps

At the water valve plug to the (not at the water valve itself) with or without the engine running:

See the attached diagram for voltage measurements. These measurements were taken with the engine running and the rotary heat control switches on full heat. I don't exactly know where to go from here. Any help would be appreciated.7711

[Clarksonvalley]

Shogun,

OK - looking at the wiring diagram you referenced in your last post, I'll plug the water valve back in and, with the engine running, both rotary heat switches set to max. and heater fan set to high speed, check for 12 volts at terminal #1. I'll also connect my test light between terminal #2 and ground, then terminal #3 and ground to see what the bulb does in both locations.

[632 Regal]

Make sure all 3 levers are all to the far right.

[shogun]

move the levers from cold to warm and back to see the differences in pulsations on the test bulb.

[Clarksonvalley]

Attached is a photo of my Water Valve Test Wiring. The two red lights are 12 volt Radio Shack bulbs. The red wire is 12 volt - actually 12.66 volts per my meter. The resistance thru each solenoid coil to ground is 12.3 ohms. With the engine running, fan on high speed, both rotary heater switches fully clockwise for full heat (except driver side is not past the full clockwise detent, garage temp = 63 deg. F. both lights are full on. If I rotate the passenger heat switch anti-clockwise, its bulb stays full on, no flickering. If I rotate the driver heat switch past the clockwise detent, both bulbs go out. There does not seem to be any voltage modulation taking place. I am wondering if the rotary switch module on the dash is buggered.


7712

[Bill R.]

You won't get a voltage variation at the heater water control valves, they operate on pulse width not variable voltage. The solenoids inside the heater control valve are spring loaded when you give them a 12v supply it opens all the way, shut the power off and it closes all the way, by rapidly pulsing this voltage you can control the open time. with the heater control turned all the way the pulsing may be too rapid for you to see it on your test light.
The control module you're referring to is not in with the rotary switches on the dash, its down under the dash in front of the cabin filter and the sword if you have one. Its the furthest forward module down there right up against the firewall. If you buy a new one on the later e34's its has to be coded to your car according to the tis. I haven't seen one fail yet but i don't work on that many e34's these days

[Clarksonvalley]

OK, so what test can I perform to determine if the Water Control Valve is functioning properly. The main reason I suspect a bad Water Control Valve is the strong electrical smell (something electrical about to burn up) I get when the system is operating. I don't get this smell when I unplug the Water Control Valve. The Aux. Water Pump runs all of the time the ignition is on or the engine is running, no electrical smell with just the Aux. Water Pump running. Do the Water Control Valves open 100% with the application of 12 volts or do they close 100% with the application of 12 volts? If the voltage to them pulses, then the valve is constantly fluttering back and forth, more open when more heat is required and more closed with less heat is required. I just need to know what to look for and how to see it. I also own a Lotus Europa - it has a cable operated valve to the heating coil - life was simple before the computer age.

[genphreak]

The wider the wave form (slower the pulses) the more the valve opens. Increasing temp on the dial slows the pulse. You cannot notice the valve fluttering as it is inside the coil casing, has a lot of mass itself and is pushing against the coolant anyway.

Past the indent on the drivers side dial simply turns the 12V PWM action off, allowing the valve to open fully (turning your test light off)

Re the smell- this should make it easier to isolate your problem. Should simply be leaking o-rings (could you be describing the smell of hot coolant I am wondering? If so you just have to carefully remove the console and replace the o-rings on the heater matrix feed pipes) or it may be the controller Bill is talking about- a hairline crack causing a relay to flicker and burn out perhaps- they are easy to remove from the Right side, just above the trans tunnel behind the carpeted panel. Once you open the controller and can see the PCB you should be able to see more effects by examining the look of the PCB and its relays.

If the smell is indeed only in the engine bay, is it really the heater valve? Given they are a wear item, you might just want to buy a new one regardless as sensible insurance anyhow. The Bosch ones are cheaper than ever now ($120), and have failed on every e34 I've had and seen recently...

[Bill R.]

7713


Here's a little better description of the heater control valves..... I personally wouldn't worry about a burning smell coming from them, they are just magnetic coils, a fuse will trip before any damage is done to anything... I suspect you're smelling something else. Genphreak your right, i had it backwards they are normally open and pulse to close.

[Clarksonvalley]

Bill,

Nope - I am definitely smelling the Water Control Valve getting hot. It is on a 15 amp fuse (F20), so if something is wrong with one of the solenoids, the circuit could draw 180 watts. This wattage could slowly fry something without blowing the fuse. I plan on replacing the Water Control Valve and see if that solves the problem.

Tom

[Clarksonvalley]

Bill, Shogun, 632 Regal and Genphreak,

Thanks for all of your help. The old days without computers were much simpler.

Tom

[shogun]

well, on our cars built in the period from around 1985-1995 it is till possible to repair electronic parts like a control module, resoldering a LKM, GM, servo control unit, even Motronic or a cluster.
On the cars which are built now there are just black boxes and the mechanics or service engineers do no longer repair, they are "change-eneers".

[632 Regal]

How hot are the solenoids getting? Can you touch them to see if they are getting real hot? I just mixed and matched 3 heater valves to get one that works yesterday and mine do not get hot until the engine heats the coolant. I have a parts pump with the solenoids if you want to mess with it, free just pay shipping and it's yours.