Motronic 2.2
- Incomplete notes -
Notes from stefan.hegnauer@gmx.ch
- several pins of the connector are not used by the bike wiring harness. For instance, the output signal of the built-in pressure sensor is there on pin 11 (and could be tampered with, if one is so inclined) or there are two serial RS-232-like lines (txd pin 16, rxd pin 34) which are attached to software; if they are used is not clear yet.
- the signal from the oxigen sensor is quantized by hardware into only three (!) levels: input voltages below ~420mV result in 5V, 420...580mV -> 3V, above ~580mV -> 1.4V. These three output voltages are then sampled by the built-in AD converter
- after a cold start (i.e. after reconnecting the battery), the Motronic puts some of its data to a static RAM which is not erased as long as fuse #5 and the battery are ok. After a warm start, a checksum is computed to see if the RAM contents are still valid.
Note: there is no connection of the Motronic (diagnostic unit) to any lights on the R1100, but is for the K1100.
- get an analogue Voltmeter (digital ones are usually not fast enough, so you could get wrong readings)
- hook it up between pin 1 of the diagnostic connector and ground (battery -, chassis), switch ignition on *
- with a separate wire, connect the same pin 1 to ground for at least 5 seconds, then remove the wire
- the needle of the voltmeter should go to nearly zero for about 2.5 seconds, then rise again to almost 12V
- a series of short dips towards zero follows - count the number of dips
- a short pause of 2.5 seconds follows
- 5 and 6 are repeated 3 times with perhaps different numbers of dips
- you have now four counts, this is the Motronic diagnostic code (see table below)
- the whole sequence, beginning with the 2.5 seconds dip of 4 above, repeats over and over until prompted again (point 3)
- the next error code (if any) is shown after prompting
* if you don't start or just very briefly turn the engine, codes 1122 and 1133 will show, which is normal!
example: one dip - pause - one dip - pause - two dips - pause - two dips - pause - long dip - pause (repeat) => code 1122
Motronic Codes
0000 no further fault stored
1111 CO potentiometer
1122 Hall signal 1
1133 Hall signal 2
1215 Throttle butterfly angle sensor
1223 Engine temperature sensor
1224 Air temperature sensor
2341 Oxygen sensor at limit
2342 Oxygen sensor signal invalid
2343 mixture setting at limit
2344 Oxygen sensor shorted to ground
2345 Oxygen sensor shorted to 12V
4444 no fault stored
Erase fault memory: pull fuse 5 for some seconds.
Most of the information given above comes from the BMW booklet 'BMW Diagnose - test instructions Motronic', # 01 71 9 789 901. This booklet is about the K1100 but seems to be valid for the R1100 as well, at least in part.
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We can do a quick check of the TPS setting on Motronic 2.2 (and I think 2.1) using the 3 position diagnostic connector. I've tested this on my '96 R1100RT and it works. I'll check my '93 K1100LT (MA 2.1) one of these days and let you know but I'm pretty sure it works the same and in addition, it lights the TEMP lamp so you don't even need the LED.
Ignition OFF
Ground Pin #3
LED + on Battery + terminal
LED - on Pin #1
Ignition ON
Now you should see the LED lit. Slightly opening the throttle should make the LED go out. If so, your TPS is within factory range.
Mick
MA2.4
Apparently one can use pin 18 in the diagnostic connector the same way one could use pin #1 on the old 3-pin flat connector (per Paul, in Holland). Haven't tried it myself. 2.4 bikes have many more diagnistic functions than 2.2 had, so any information you get from pin #18 will only be a small part of what can be seen with a MoDiTeC or a GT1.
CCPs and CO pots
All hearsay...
Very early '94 models had only one map in the ECU and no CCP. Disconnect the O2 sensor and plug in the pot.
Later '94 models had the CCP. If you pull the CCP with the O2 still installed, it will go to "limp home" mode, but pulling it with the O2 disconnected makes it look for the pot.
Models after 94 may need a "No O2" CCP to tell the Motronic to look at the pot. Again, pulling the CCP sends the ECU into limp mode.
Motronic
