Operation of M70 lock sensor, lock sensor delete info

[shogun]

The lock sensor consists of a control unit and speed sensor (lock sensor) on the AC compressor.
This lock sensor is ONLY installed on models with the M70 engine
(E32 750, E32 850) because the AC compressor and water pump are driven by the same ribbed drive belt.
If the ribbed drive belt tears or jumps off of the pulley when the compressor locks, the engine cooling system would also fail.
This is prevented by the electronics of the lock sensor control unit.
It continuously controls engine speed and compressor speed and immediately switches the magnetic clutch of the compressor off when there is more than 30% slip.
This control unit also controls coolant temperature and at first times the compressor in case of overheating and switches it off later if the temperature rises further.

After starting the engine and exceeding an engine speed of 600 RPM
for the first time the control unit is activated, the compressor is switched on, engine speed is continiously compared with compressor speed and coolant temperature is measured. If during a measuring period of 200 milliseconds slip is recognized once at high speed or slip is recognized three times at low speed, the compressor will be switched off.

Important: the compressor can only be switched on again if the engine is started again.
In case of fault and when a mechanical defect of the compressor cannot be found, check whether brief slip has occured while driving through a puddle (wet ribbed drive belt).

Monitoring of the coolant temperature takes place parallel to monitoring of slip. If the coolant temperature exceeds the 117 degree C. mark with rising tendency, the compressor will be timed, i.e the magnetic clutch of the compressor will be switch off for 20 seconds every 40 seconds. If this measure causes the coolant to drop below 114 degree C., the compressor will be switched on again continiously. However, if it rises again to 120 degree C., the compressor will be switched off untill it is below the 114 degree C. mark.

see page 64-90/1 repair manual no. 6
http://www.bmwtechinfo.com/repair/main/Index_cd3.htm

[estoque]

After taking my 91 850i to two shops still no fix for my AC...I’ve been looking for information on how to modify the lock sensor to make new compressors work with the car but all the threads are old and the images/links no longer work. Does anyone have the information on how to modify the sensor? I also read if you buy the newer sensor it will work with new compressors is this the correct part number? 61358360039 I searched for one and it’s not available anywhere. The summer was almost unbearable driving in my 8er but now the weather is cooling down and I can actually drive with my windows up lol.

[cartoonz]

OK, this is what you have to do:

Behind the speaker in the LH (Driver's) footwell, is the compressor Lock Sensor.
Remove hood release handle
Remove left speaker kick panel / plastic cover
Remove the speaker pod
There is a plastic box on the inside lower wall of the body cavity, held on by 2(?) nuts on sheet metal. Nuts are outside, towards where your feet would be. Remove those
Now you can reach down and fish the entire thing up and out of the hole.

Great, so now you have this weird box with too many wires in your hand, what to do?

You need to jumper 2 wires.
The wires you need are these:
pin #3 - Black/Red/Yellow
pin #5 - Black/Gray (there are TWO of them that go to the same pin, use either one)

Do NOT cut them out of the original circuit, but strip a bit of insulation off and jumper them together 3-5" before the connector (X77) to the box, tape up the splice & reinstall everything.

Now you can use a new R134 Denso/whatever single wire compressor.

[shogun]

that were some additional info posted in the E31 forum and copied to here.
==========================================
BMW TSB B64 11 92 (3569) E31 850, E32 750 AC compressor shut down

Situation: AC compressor shuts down during heavy rain, or when driving thru deep standing water. The customer complaint is loss of cooling. The condition disappears when engine is stopped and restarted.

Cause: The AC compressor clutch is disengaged by the slip monitoring function of the AC lock sensor control module. This module continiously monitors the engine speed and compares this to the AC compressor speed. The magnetic clutch of the compressor is automatically disengaged by the lock sensor module if the amount of slip exceeds 30%. The intent of this system is to prevent broken v-belt or reduced engine cooling if the AC compressor locks up. If the vehicle is driven in heavy rain or if standing water is spashed up into the engine compartment belt area, the v-belt and pulley may get wet enough to cause slippage in excess of 30%. The lock sensor control module perceives this as possible AC compressor lock up and opens the clutch circuit to prevent damage. The control module will remain in this state with the compressor clutch deactivated until the ignition is turned off and back on, clearing the condition.

Note: in addition to slip monitoring, an engine coolant temperature check has been incorporated into the lock sensor module on E32 vehicles produced since 09/1989, and E31 vehicles since the start of production. If engine coolant temperature rises above 240 degrees F., the AC compressor clutch is pulsed off at regular intervals to reduce engine load. If the coolant temperature rises above 250 degrees F., the clutch is switched off completely. As of 09/1992 production the slip monitoring fuction of the AC lock sensor module will be dropped on both E31 and E32 models.

Solution: If a customer complaint of AC cooling loss is received, the following items should be checked before proceeding with this repair:
-AC compressor belt tension adjusted to specification
-No oil leaks have contaminated the AC compressor belt, causing slip
-AC system pressure is within specificaion, not overloading compressor and belt.

If the above checks do not isolate the source of the slippage, proceed with the following repair. The remedy for this siwation varies with the model and production date of the vehicle. Refer to the appropriate ETM for diagrams showing connector, pin and control module locations.

750iL vehicles from the start of production thru 08/1989
Remove the lock sensor control module from the from the left hand side of the drivers footwell. The unit has 2 connctors, 4-pin and 5-pin and is located in the recesss of behind the kick panel.
Unplug the connectors X77 and X80 from the lock sensor control module body.
Remove pin 1 of connector X77 and pin 3 of connector X80 using a terminals removing tool.
Cut off the terminals and connect the loose wires with an insulated crimp connector. Shrink tubing may also be necessary to prvide proper insulation.
Tape or tie-wrap the loose wires with the other harness wires.
Plug the connectors back into the control module, reinstall the control module and reinstall the kick panel trim.


E32 750iL produced from 09/1989 thru 08/1991:
Remove the lock sensor control module from the left hand side of the drivers footwell, the unit also has 2 connectors, 4-pin and 5-pin.
Replace the lock sensor control module with p/n 61352233107 . This replacement module does not contain the slip monitoring function.
Reconnect the electrical connectors and install control module and kick panel trim.

E31 from start of production thru 08/1992:
E32 750iL vehicles produced from 09/1991 thru 08/1992:

Remove lock sensor control module from left side of driver's footwell. The unit has 1 connector with 10 pins and is loacted in the recess behind the kick panel.
Replace the lock sensor control module with p/n 61358360039 , this replacement module does not contain the slip monitoring function.
Reconnect and install....

Parts information:
lock sensor module 61358360039 10-pin type E31 from start thru 08/1992, E32 from 09/1991 thru 08/1992.
lock sensor module 61352233107 , 9-pin type, E32 from 09/1989 thru 08/1991

[shogun]

more info how to delete the lock sensor
the compressor of the E32 750 and the E31 850 has 3 wire connections and 2 of them go to the lower side of the compressor to the lock sensor = Hall-speed sensor = pulse sender.

The sensor is for the supervision of the RPM of the compressor, in case the RPM deviates by more than 30% from the RPM of the engine, the compressor will be switch off. Reason is that in case the compressor seizes it would damage the belt which on the 750 and 850 also drives the water pump. Therefore in the older version of the compressor there is this safety function to disconnect the compressor in such a case.
Newer compressors (at least on the E31 850 as I understand)
do not have this lock sensor anymore and the compressors have only one connection instead of 3. Therefore also a new lock sensor control module is required.

In case of a compressor without lock sensor the following can be made according to E32Fan from Canada which is an electronic engineer and also owns an E32:

quote

Details are on pg 6450-22 & 23 athttp://www.e38.org/e32/e32_88_etm.pdf

I would open the A26 Lock Sensor Control Unit and solder a jumper wire across the Normally Open relay contacts. This will short X80 pin 3 to X77 pin 1 (shorting SW/RT/GE to SW/GR).

If there are no pulses from the reed relay in the compressor (because the new compressor has no reed relay) then A26 will de-energize its relay, but we won't care because the contacts are now shorted.

This will allow the compressor to run whenever K19 is energized and the pressure switches B7 and B8 are closed (just as in 735iL)

In later years, A26 was modified. The connector became X9968 which is not documented in the connector Views 8500. See 6450-22 at http://www.e38.org/e32/e32_92_etm.pdf

I do not see any outputs from A26 that will bother EML, so I would not expect any problems from shorting the A26 relay. The SW/GR wire to EML is just the compressor run signal to inform EML that there is a compressor load.

unquote


Apparently also the EML gets a signal from the lock sensor, see pin 44, and pin 41 is for the aircon relay

Steckerbelegung/pinout

Pin 1 EML Pedalwertgeber/EML throttle poti
Pin 2 EML Pedalwertgeber/EML throttle poti
Pin 3 frei/ free
Pin 4 ABS/ASC/ASC+T Steuergeraet/control unit
Pin 5 DME Steuergeraet 1 / Motronic cylinder row 1
Pin 6 EML Pedalwertgeber / DME Steuergerät 1
Pin 7 EML Pedalwertgeber/pedal poti
Pin 8 Instrumentenkombi/instrument cluster
Pin 9 EML Pedalwertgeber/pedal poti
Pin 10 EML Stellmotor 2/EML adjusting motor 2
Pin 11 EML Stellmotor 2
Pin 12 EML Stellmotor 1
Pin 13 RXD Datenleitung / RXD data line
Pin 14 Masse ground
Pin 15 EML Leuchte Instrumentenkombi/ EML light instrument cluster
Pin 16 EML Stellmotor 2
Pin 17 EML Stellmotor 1
Pin 18 Hauptrelais 2/ main relay 1
Pin 19 Masse / ground
Pin 20 EGS Steuergeraet / transmission control module
Pin 21 frei / free
Pin 22 Steuergeraet ABS/ASC/ASC+T control module
Pin 23 Steuergeraet ABS/ASC/ASC+T control module
Pin 24 frei / free
Pin 25 frei / free
Pin 26 EML Stellmotor 1
Pin 27 EML Stellmotor 1
Pin 28 EML Stellmotor 2
Pin 29 frei / free
Pin 30 Masse / ground
Pin 31 Kuehlwassertemperaturfuehler/ coolant emperature feeler
Pin 32 EML Pedalwertgeber/DME Steuergeraet 2
Pin 33 DME Steuergeraet 2
Pin 34 EML Stellmotor 2
Pin 35 EML Stellmotor 1
Pin 36 Hauptrelais 2 main relay 2
Pin 37 Hauptrelais 2 main relay 2
Pin 38 EML Stellmotor 1
Pin 39 frei / free
Pin 40 EML Stellmotor 2
Pin 41 Klimaanlagenrelais / climate control relay
Pin 42 Getriebewaehlschalter/transmission selector switch
Pin 43 Schalter Geschwindigkeitsregelung/switch speed regulation
Pin 44 Steuergeraet Lock Sensor
Pin 45 Kuehlwassertemperaturfuehler /coolant temperature feeler
Pin 46 EML Pedalwertgeber
Pin 47 DME Steuergeraet 1
Pin 48 frei / free
Pin 49 DME Steuergeraet 1
Pin 50 DME Steuergeraet 2
Pin 51 frei
Pin 52 EGS Steuergeraet / control module
Pin 53 ABS/ASC/ASC+T Steuergeraet
Pin 54 frei / free
Pin 55 TXD Datenleitung/ data line

additional info from E32 Fan: This diagram shows where the Jumper needs to be soldered. If you remove the module cover and plug it into the sockets, you can trace the BLK/RED/YEL and BLK/GRY wires and see that they lead to the relay contacts.
http://s1011.photobucket.com/user/E3...?sort=3&page=1
link does not work anymore, I uploaded from my PC what I saved below



http://www.bimmerboard.com/forums/posts/1221130/
http://www.bimmerboard.com/forums/posts/1221242
https://www.bimmerforums.com/forum/s...5#post30580695
https://www.bimmerforums.com/forum/s...or-91-E31-850i


from Johan
750 lock sensor 3 pins compressor vs 1 pins compressor -
As the pump in my 750 seems to leak uv dye around the compressor seal I got myself a new one. Later I saw the new one has only 1 connection in the electrical plug and thus missing the speed signal. And ofcourse no where to mount it so I can't transplant is.

So I did some schematics checking and came up with the following:

There are two types of lock sensors. The first one was used with the R12 upto 09/91. The second after that with R134a. As these have different plugs they don't "officially" interchange.

The part numbers of the old/R12 one in order they appeared:
61351382833
61351388718
61351390899
The part numbers of the new/R134a one in order they apeared:
61351392410
61358360039

The pin-out of the first type (two connectors):
x80-1 -- BL - to compressor rpm sensor
x80-2 -- BL/BR - to compressor rpm sensor
x80-3 -- SW/RT/GE - 12v from compressor relay

x77-1 -- SW/GR - To compressor clutch
x77-2 -- GN/BL/GE - 12v in Run/Start Fuse 29
x77-3 -- BR/SW - ground
x77-4 -- SW - to DME, EML,..etc. engine rpm

The pin-out of the second type (one connector):
x9988-2 -- BR/SW - Ground
x9988-3 -- SW/RT/GE - 12v from compressor relay
x9988-4 -- GN/BL/GE - 12v Run/Start Fuse 29
x9988-5 -- SW/GR - to compressor clutch
x9988-7 -- BR/GE - tap on cluster (x16-24) engine temp sensor
x9988-9 -- BR/VI - tap on cluster (x16-26) engine temp sensor
x9988-10 - SW - DME, EML, cluster,..etc. engine rpm

According to the ETK I need a new lock sensor 61 35 8 360 039 and an adapter wiring set 64 52 8 391 881. My guess is that the adapter wiring set goes between the car and the new lock sensor.
But as the compressor cost enough and I recently had the chance to pick some parts off a 93 750i I am now the proud owner of a 61351392410 lock sensor with loose some wires. So my plan is to splice the new plug into the wiring of the car, leave the temperature wires alone thus enabling me to use the newer lock sensor which doesnt need the compressor speed signal. If this doesn't work I'll tap into the cluster temp sensor and then it's 100% identical to the 92 upwards model years ans must work.
It seems to me in theory there are two other ways to bypass the old lock sensor:
1) Wire the input 12v from the compressor relay to the output to the compressor clutch thus bypassing the sensor
2) Also cut the x77-4 black wire so the lock sensor reads the compressor speed as 0 (as there is no speed sensor) and the rpm as zero (engine not running). This could fool the unit as it matches to two signals and disengages when the speed difference is 30% or more.
-->Both methods disable functioning of the sensor completely so use at own risk!
I found some postings on the net from Shogun and Hitmax which pointed me in the right direction. But as I collected all the part numbers and pinouts I though I'd share it just the same.
1989 e32 750i

[rjjablo]

Wiring DiagramAttachment 680231

[Ericks2002]

I was looking at the coloring for the wiring diagram and it says GR Means grey and GN stands for green. Are the wires going into pin 5 black green or black grey? I am going to do this soon I was just trying to confirm the right wires before I got everything apart.

[Timm]

The full diagram is here - and there are a few different versions over the model years: https://www.meeknet.co.uk/e31/e31_91.pdf#page=311

Wire colours are shown here: https://www.meeknet.co.uk/e31/e31_95.pdf#page=20

[Ericks2002]

Got my module out and the two wires at pin 5 are black and grey like the wiring diagram suggest. Pin 3 is black red and yellow. I think cartoonz made a small error. Just trying to be careful because I dont wanna splice wires incorrectly.

I wanted to post a pic of the connector but I can’t figure out how at the moment.

[Timm]

Probably no error - there were a few variants over the years!

[estoque]

Got my module out and the two wires at pin 5 are black and grey like the wiring diagram suggest. Pin 3 is black red and yellow. I think cartoonz made a small error. Just trying to be careful because I dont wanna splice wires incorrectly.

I wanted to post a pic of the connector but I can’t figure out how at the moment.

mine also didn’t match the diagrams if the wires are in the correct PIN numbers then it should be fine

[shogun]

copied from the DIY site of O.J. which works again:
AC Lock Sensor
Please note that year designations might not correspond properly depending on European or US manufacturing models. The AC electronic system consists of several components.
The heater controls and IHKA control module
AC pressure switch on the drier bottle
Some models have a 108C coolant temperatur switch off device
The AC lock sensor module
AC compressor relay
Aux fan relays
The AC lock sensor monitors engine coolant temperature, compressor speed and engine speed. If all is well it allows the AC compressor to get 12 volts applied to enable the system. In this example the control unit is from an V12 750 1989 model, part.no. 61.35.1.390.899(2).
Note! Only 750's have an AC lock sensor! The unit is located on a bracket behind the left kick panel. Remove the kick panel to expose the two bolts that need to be loosened to hook the bracket off the chassis. The bracke also holds the Servotronic (if present) and AC compressor relay (1988 to 1991 models).
It's either got two green connectors or one bigger green connector. All in all there should be 9 pins if there's two connectors, and 10 pins if there's 1 connector. Not necessarily all are connected though.
1988 750's
Pin ........... Wire color............................................. .. Description
C1-1 ................Black / Grey....................................To DME's. Signals to increase idle speed when AC is running.
........................Blue...................... .........................To AC compressor. 12 volts to enable compressor.
C1-2.................Green / Blue / Yellow .......................Fuse 29 (12 volts when ignition in start or run)
C1-3.................Brown / Black................................... Ground
C1-4.................Black........................... ....................DME pin 6. Engine speed signal from coil # 1
C1-5.................Brown / Violet...................................Engine coolant temp.sensor (brown/white)
C2-1.................Black / Grey.......................................AC compressor speed signal (1 of 2)
C2-2.................Blue / Brown.....................................AC compressor speed signal (2 of 2)
C2-3.................Black / Red / Yellow...........................Low pressure switch* (source of 12 volts for compressor)
C2-4.................Brown / Yellow..................................Engine coolant temp.sensor

*) The other end of the low pressure switch connects to the high pressure switch by a Black / Red wire. It then connects to the AC compressor relay via a Black / Red wire again. When the IHKA grounds pin A8 (Blue / Black wire) it enables the AC compressor relay which the energizes the Black / Red wire from fuse 29 (7.5A). The AC relay is connected to this fuse via two Green / Blue / Yellow wires. If the AC system pressure is correct, a 12 volt should be available at this pin when the AC mode is enable at the heater controls (ign. switch in position II or engine running).

1989 - 90 750's
Pin.........Wire color............................................. ..............................Description
C1-1.......Black / Grey....................................To DME's. Signals to increase idle speed when AC is running.
.............Black / Grey.....................................To AC compressor. 12 volts to enable compressor.
C1-2......Green / Blue / Yellow.........................Fuse 29 (12 volts when ignition in start or run)
C1-3......Brown / Black...................................Ground
C1-4......Black...................................... .........DME pin 6. Engine speed signal from coil # 1
C1-5......Brown / Violet....................................Engine coolant temp.sensor (brown/white)
C2-1......Blue....................................... ...........AC compressor speed signal (1 of 2)
C2-2......Blue / Brown...................................... AC compressor speed signal (2 of 2)
C2-3......Black / Red / Yellow............................. Pressure switch* (source of 12 volts for compressor)
C2-4......Brown / Yellow.....................................Engine coolant temp.sensor

*) The pressure switch is now an integrated 3-way switch in one instead of multiple switches. The other side of the pressure switch is connected to the AC compressor relay via a Black / Red wire. The pressure switch also has two other wires (Black / Grey / Yellow and Brown / Black) that controls the aux fan relay. The AC compressor relay is the source of the AC compressor 12 volt enable signal. It's hooked up to fuse 29 (7.5A) via two Green / Blue / Yellow wires. The IHKA pin A8 (Blue / Black) grounds the AC compressor relay thus enabling 12 volts to pass to the pressure switch, and to the lock sensor if the AC system pressure is correct (ign.switch in position II or engine running).

1991 - 1992 750's
Pin.......... Wire color........................................ Description
1...........Blue.................................. .AC compressor speed signal (1 of 2)
2..........Brown / Black.......................Ground
3..........Black / Red / Yellow...............Low pressure switch* (source of 12 volts for compressor)
4..........Green / Blue / Yellow.............Fuse 29 (12 volts when ign. in pos. II or engine running)
5..........Black / Grey.........................to AC compressor. 12 volts to enable compressor. Is also connected to DME to increase idle speed.
6..........Blue / Brown..........................AC compressor speed signal (2 of 2)
7..........Brown / Yellow........................Engine coolant temp.sensor
8..........N/C
9..........Brown / Violet........................Engine coolant temp.sensor
10........Black................................... ..DME and coil. Engine speed.

*) The pressure switch is now an integrated 3-way switch in one instead of multiple switches. The other side of the pressure switch is connected to the AC compressor relay via a Black / Red wire. The pressure switch also has two other wires (Black / Grey / Yellow and Brown / Black) that controls the aux fan relay. The AC compressor relay is the source of the AC compressor 12 volt enable signal. It's hooked up to fuse 29 (7.5A) via two Green / Blue / Yellow wires. The IHKA pin A8 (Blue / Black) grounds the AC compressor relay thus enabling 12 volts to pass to the pressure switch, and to the lock sensor if the AC system pressure is correct (ign.switch in position II or engine running).

1993 - 1994 750's
Pin...........Wire color............................................. .....Description
1................N/C
2................Brown / Black Ground
3................Black / Red / Yellow....... Low pressure switch* (source of 12 volts for compressor)
4................Green / Blue / Yellow........Fuse 29 (12 volts when ign. in pos. II or engine running)
5................Black / Grey....................To AC compressor. 12 volts to enable compressor. Is also connected to DME to increase idle speed.
6................N/C
7................Brown / Yellow..................Engine coolant temp. sensor
8................N/C
9................Brown / Violet...................Engine coolant temp.sensor
10..............Black............................. ...DME and coil. Engine speed.

*) The pressure switch is now an integrated 3-way switch in one instead of multiple switches. The other side of the pressure switch is connected to the AC compressor relay via a Black / Red wire. The pressure switch also has two other wires (Black / Grey / Yellow and Brown / Black) that controls the aux fan relay. The AC compressor relay is the source of the AC compressor 12 volt enable signal. It's hooked up to fuse 29 (7.5A) via two Green / Blue / Yellow wires. The IHKA pin A8 (Blue / Black) grounds the AC compressor relay thus enabling 12 volts to pass to the pressure switch, and to the lock sensor if the AC system pressure is correct (ign.switch in position II or engine running).

Opening the unit by carefully pushing away the 4 clips on the side of the casing and pulling the top away from the bottom. see link below.
You can then remove the PCB (printed circuit board) from the bottom casing by carefully pushing out near the 4 tabs that hold the PCB in place, and pulling the PCB up and free from the bottom casing.
The PCB contains 3 IC's (integrated circuits), a relay, some diodes, transistors, capacitors and resistors.
Note! The following is specific to this exact part.no device. Yours may vary.
The top IC is a LM2901 quad comparator IC.
The right long vertical mounted one is a COP87L42CJN-1N 8-bit CMOS microprocessor with 4kbit ROM and 128 bytes memory (BMW label 6563000049081-1, verified by M.P.).
The lower thin one (marked IC2) is not labeled (or covered in black paint). Most likely an A/D converter for the engine coolant temperature.
The relay is from Siemens and a V23072-C1061-A208 / BC5MC) model.

http://www.ow.no/index.php?option=co...d=59&Itemid=13