BMW M52 engine.
Black mot88 connector lock is slightly different from the natural color M50 (either type can be used with a bit of filing).
The mot88 pinout is VERY different. So do NOT plug into the other type.
See [M50-vanos-vs-s50b32.xls] columns.
Prelling
We received a report of some relay prelling (when ignition off) that we cannot reproduce.
- powering up p259 outputs through a small 30A relay (or 2 in parallel) to +12V without powering the ECU.
- this is assumed (and verified) to "flyback-ed to inj flyback equivalent to EC36/27"
- not to ECU power mot88/49 (=EC36/25 switched 12V) - that would explain if the solenoid is strong enough to provide ECU supply current. Verified that no diode to ECU power.
What should be hooked to the mot88 (which pin) to simulate the "ignition off" state ?
- In the car the main relay controlled by mot88/73 supply is fed by mot88/26 VBATT constant 12V from the battery, the ECU is powered via the Ignition switch 12V+
- so if the main relay is ON and the ECU is switched off via the switch it seems to stick on when protection diodes are connected to mot88/49 (=EC36/25 switched 12V).
- The flyback=mot88/87 (not pin54 in the xls beware, that is cam sensor +12V!) in the car also comes from the main relay but could possibly be moved to a constant 12V (pin26) instead to solve this?
- good find: apparently the mot88/54 = mot88/49 (12V connection wire) inside the ECU is simply not needed, if the mot88/54 is supplied from the harness (weird, why is it connected back to the ECU at all ?)
- Can a failed diode in the relay cause this?
- possible, but more likely the mot88/54 cam12V seems to be unnecessary from the ECU if the harness feeds 12V there (via main relay) anyway
OEM wiring information here
http://www.gbnetwork.co.uk/bmw/ftp/etm_e36_1998final.zip
Page 108 shows the way it´s wired.
- EC36/25 = mot88/49 = 12V switched (ECU main supply)
- EC36/16 (p259/ch1) = mot88/73 main relay (not EC36/5 GND)
- why not some output ? Which output should control mot88/73 ?
- EC36/23 = flyback 12V = mot88/87 flyback
- flyback 12V = mot88/54 cam12V
- flyback 12V = mot88/65 cam12V
The bold, or last 2 are suspect to cause prelling, especially if switched 12V (ECU main supply) is connected to cam12V in the harness
- the ECU might be powered from the cam12V unintentionally
- this was not present in any of our previous experimental bench setup tests.