Subpage of MembersPage/BmwMFiftyTwo
note:
- BMW88/.. = BMWM52/.. = M52/.. used interchangebly
- please be careful with DVM when measuring: DVM in current mode (or probe plugged to the wrong banana-socket) can cause short. Shorting ECU output to +12V might cause damage (to ECU, DVM, harness, or other parts).
- See MembersPage/BmwMFiftyTwoMainRelayTesting
DME relay out is connected to BMWM52/54 and BMWM52/87 (exactly same net in M52 harness: confirmed)
Note: measuring on M52/87 there might be a weak pullup to 12V (ECU supply M52/49=EC36/25) via 1k and a diode. This might be confusing when measuring with DVM (>= 1M Ohm internal resistance), but absolutely normal, and not causing any problem at all. Actually caused by 1k pullup of EC36/4 pullup resistor, and low voltage flyback on same pin.
- as an experiment, pull down (easiest at the injector+) to GND with 1k and measure appr 6V (or pull down with 270 Ohm to GND and measure appr 2.53V).
BMWM52/73 DME main relay input (brown wire, yes, weird but brown)
- pulled down by EC36/16 (=p259/ch1) to 0.2V (when tested with 75 Ohm pullup to 12V)
- DME main relay (in harness) switches 12V to BMWM52/54 (DME relay out) and BMW88/87 (injector shared) supply
- BMWM52/54 (and BMWM52/87) are pulled to 12V by DME relay out: confirmed by measurement
- note: BMWM52/54 (DME relay out) is left open inside ECU.
- but BMWM52/73 ->| low voltage flyback to BMWM52/87 means the DME relay slightly powers
- high voltage flyback (cathode of 30V transient diode) desired for M52/73 DME relay. Assembly note: remove the low voltage SMD on the bottom of v3.8 (this does NOT effect operation, only poweroff consumption in case something in the harness "node15" leaks current even if turned off)
DME relay out is connected to BMW88/54 and BMW88/87 (traditionally flyback)
- because of the DME relay powering the harness (supplying 12V), there is no reason for the ECU to provide 12V to BMW88/pin87 or BMW88/54
See also: