E32 IHKA 53 pages tech training material

[shogun]

with many drawings, tech details, in German language. Even if you do not understand German, a very valuable help for trouble shooting
http://www.bimmerboard.com/forums/posts/131541

[shogun]

direct link
2.09 MB Klimaautomatik IHKA Integrierte Heizungs- und Klimaautomatik, Seminararbeitsmaterial, 53 pages
http://www.e38.org/e32/klimaautomatik.pdf

[shogun]

In case you need a replacement IHKA control module and want to buy a used one, pay attention that there are different plug versions
Here the differences shown from a 1988 E32 and another one from a 1993 740iL, which Richinvan sent me

https://www.dropbox.com/s/166wm3depr...2015.46.37.jpg
https://www.dropbox.com/s/wzzyqu3tia...2015.46.29.jpg

I have found in my parts box both versions, but do not know from which model years.Sticker say:

Bosch Made in France
9140 010 224 IHKA
BMW 8 367 839.9 6411
this is the version where the plugs are clipsed in

Bosch 1147328134 Made in France
9140 010 005 IHKA
BMW 8390 000.0 6411
plugs go straight in.

Johan told me that there was a change in plugs around 1990-1991.
So whenever you order a IHKA module, make sure you get the same version, because the plugs on the wire loom side you cannot change which go into the IHKA modules.


Another interesting mod:
Modification of the IHKA control unit (E32/E34) due to overheating 2.39 MB!!
http://www.e32-schrauber.de/bmw/date...difikation.pdf
(Text copied)
The IHKA control unit repeatedly failed after about one hour of driving. In “cold condition” (directly after starting) the unit worked perfectly. The possible root cause was overheating of the entire unit. The housing is completely closed and on the PCB there are several components generating considerable heat. As a solution an active cooling was built in. The cut-outs are located over the components which generated the largest amount of heat. The two fans (30x30x7) were built into the “step” of the housing; there is enough space to the opposing electronic components. At the upper end of the PCB both +12V (KL 15) and ground can be found. There are two massive tracks adjacent to each other. Here a connector was soldered on (after removal of the protection coating, of course. Grind it until you see shiny copper…). There are 5 diodes (1N4001 or eqiv.) between +12V and the fans. The fans are running more silently at 10V (13.8V – 5 x 0.7V). For testing this modification the temperatures at two components (heat sink left – Temp 1, resistor right – Temp 2) were measured. Until about 4400 sec. (1 ¼ h) the control unit was idling – just supplied with 13.8V, no switching, no stepper driving, nothing – but 65°C at the resistor! Then the fans were switched on…
During messing around with the IHKA control unit to determine the cause of the malfunction I tried to find out more about how the IHKA was built up. Unfortunately the main components (microcontroller, driver IC’s,…) are marked with a special code – sorry, no proven information about these items.Thus: all following information is based on my own fuzzy thoughts about how this unit may work…(Picture and overview at the end of this document)
The IHKA control unit is diagnosis capable, i.e. (almost) all of the currents / voltages are measured and supervised. This is done by the power resistors together with the LM2901’s which compare analog values (set/actual) and deliver a corresponding digital signal to the main controller. This may evolve to a real PITA as each signal which is not exactly inside the defined limits will trigger an error message. If some values drift over the years there may be error messages where no errors are…
The stepper motor’s four windings are switched low side (ground) by the ULN2003’s. The bit pattern is stored by the stepper controller into the shift registers (HEF4094) which pass the signals on to the ULN2003’s. There are two driver-IC’s for switching the heating valves etc. (unfortunately these IC’s are coded: L475D). And exactly here is one of the big puzzles of the circuit: adjacent to these drivers there are two 120 Ohm power resistors. But those are not in a ground path due to current measurement or similar, they are just powered – a heating! Why? No clue… I only know one reason for providing such a “senseless” load: even in idle mode the control unit draws a defined amount of current and may be detected by other components of the entire car system. But: exactly those resistors generate a considerable amount of heat! All pictures I found in the web show a nicely tanned area on the PCB around
these resistors… thus I milled the openings in the housing directly above them. The next heater is the PTC of the fan of the interior temperature sensor. A PTC acts like a fuse. In normal operation it has a low resistance and passes current through. If there is too much current (e.g. a short), it gets hot and changes to a high resistance. The problem: if it gets heated from the “outside” (the overheated housing) it will change to a high resistance and the main controller gets the error message: “short in the fan”. This may be the main problem of the IHKA control unit…Last not least there is the main switch transistor. It is located on the same heat sink as the 5V voltage regulator for the digital circuitry. The transistor switches the KL30 supply (always hot) onto the internal KL15 (hot on ignition). Thus the control unit is powered during the often cited two minutes after engine stop and is switched off after this time. Again a problem: the main transistor itself is switched by secondary switching transistors. Latter ones are the said BC337’s. If they burn out the main transistor is permanently powered and it will never shut down the control unit – the battery will be empty soon enough (…it needs to power the fancy 120 Ohm heating…).
The main controller is very likely one of the Motorola MC6805 family. Some of the pins can be determined with a high probability (supply, Xtal,...). The reset pin was very interesting – the trace leads to one of the LM2901. In the original condition this part of the PCB was very sensitive, as the circuit remained in reset state if I touched one of the inputs of the LM2901 with the scope probe (!). After having changed the “surrounding” capacitors, this phenomenon has disappeared…
If the IHKA control unit is already opened and the soldering iron is ready I would change the two BC337 and the capacitors which are populated nearby the heat sink (2 x electrolytic caps, 2 x tantal caps).

[RandalLovelace]

Interesting solution - and one that I could do as I have many 12v and 3v computer fans laying about (as that is my other hobby). As of yet my car doesn't have this issue, but never know what the future holds.

[shogun]

well, we discussed it again on the forum on Germany. One of the electronic wizzards there is of the following opinion with regards to a modification with a cooling fan:

Natuerlich koennte eine geregelter Luefter Abhilfe schaffen. In meinen Augen ist das aber eine reine Folgenbekaempfung. Es gibt bei dem Steuergeraet ein paar "Heizungen". Das sind die 120 Ohm Widerstaende und die Linearregler. Das Problem ist nicht die Waerme der Bauelemente, sonder die Alterung durch die Waerme.
Deswegen:
Ein Luefter beguenstigt die Thermik, jedoch bleiben die gealterten Bauelemente unangetastet und diese altern langsamer weiter. Man verlaengert die Lebenszeit und loest Probleme nur scheinbar.Sinnvoller ist der konsequente Austausch der Kondensatoren. Das Sind 20 Stueck und eine Stunde Arbeit. Im Ergebnis passen die Spannungen, die Flanken schauen wieder sauber aus und die Regelung der Klima geht wieder. Das ist guenstiger als da was zusaetzlich einzubauen was das eigentliche Problem nicht beseitigt. Bei den Reparaturen die ich gemacht habe, musste ich immer R168, R169 nachloeten (mit bleihaltigen Lot). Ebenfalls kam es auch zu defekten von T520, T504. Es war bestimmt eine Folge von defekten Kondensatoren.

translation:

Of course a controlled fan can help . In my opinion, however, hat is a pure delay of damages but not a repair . There are inside the control module a few " heaters " . These are the 120 Ohm resistors and the linear regulators. The problem is not the heat development of the components , it is the aging of the components by the heat.
Therefore:
A fan keeps temperatures lower , but the aged components remain untouched and this aging continues, just a bit slower because of cooler temperatures. It prolongs the lifetime and solves problems only apparently. The best is replacement of the capacitors. There are 20 pieces and one hour of work . As a result, the electric conditions are like new , the edges look again clean and the regulation of the air works again. That is cheaper than installing a fan which does not solve the main problem. For the repairs I have done , I always had to resolder R168 , R169 ( ( with leaded solder ) . Also , there were also defects on T520 , T504 . It was certainly a consequence of defective capacitors.
----------
They are shown here, resolder them http://www.voss-tronic.de/bmw/
Companies like ProGrama Inc. do that repair

[shogun]

Link in my 2nd post is dead at the moment, here recovered with the wayback machine, German language, 52 pages IHKA training material, download it https://web.archive.org/web/20170405...aautomatik.pdf

[shogun]

BMW Technical Training Documents Climate Control Systems and Functions https://ia801005.us.archive.org/11/i...0Functions.pdf