How would i determine the color of the wire going to pin 70 on DME Motronic 3.1?

[Jon K]

NT, thx.

[winfred]

http://members.cox.net/wdixon27/etm%20e36.jpg

[Jon K]

Winfred, so which wire is the signal wire?

[winfred]

oops i went back and checked the key and it says yellow, gee how could i of guessed wrong it's so obvious

[Javier]

Javier

[winfred]

yea 70 looks like the signal on the schmatic

[ryan roopnarine]

Javier


maybe a slight mixup on your part there. i have the bentley in my lap. for 1992 m50 (3.1 motronic)

Yellow is n 71
blk is n 70

at least according to this

[winfred]

however on the sensor wires themselves the black is the signal and gray is ground, the two white's are the heater

[Jon K]

however on the sensor wires themselves the black is the signal and gray is ground, the two white's are the heater


So if you were to be tapping one for signal, which would you go for.

[winfred]

i am 20 miles from my bentley collection and all i have is my bmw etm


maybe a slight mixup on your part there. i have the bentley in my lap. for 1992 m50 (3.1 motronic)

Yellow is n 71
blk is n 70

at least according to this

[Jon K]

maybe a slight mixup on your part there. i have the bentley in my lap. for 1992 m50 (3.1 motronic)

Yellow is n 71
blk is n 70

at least according to this


Ryan according to my Bentley PDF #70 is signal... page 130-24

[Javier]

from BMW also have yellow at 71/ground and Black on 70/signal.


Javier

[Jon K]

from BMW also have yellow at 71/ground and Black on 70/signal.


Javier


Great.... so.... which one would you guys do? haha... i want to get it the first time, im not sure if damage could be done by tapping the wrong one. I am tapping it for readings, not sending... so i assume no damage but still...

[winfred]

you should be able to tell with my meter which was live, ohm where the black wire off the sensor comes out 70 or 71 or whatever, i think it's the yellow one because the harness pig tail i use for testing later 02 sensors the yellow one hooks to the black on the sensor


So if you were to be tapping one for signal, which would you go for.

[Jon K]

you should be able to tell with my meter which was live, ohm where the black wire off the sensor comes out 70 or 71 or whatever, i think it's the yellow one because the harness pig tail i use for testing later 02 sensors the yellow one hooks to the black on the sensor



Yeah im just using gut instinct thinking its the yellow also... but you know, I want to be right rather than have to splice my DME back together haha.

[Javier]

ground, the one with about 5 Vdc is the signal side of the sensor, the one with 0 Vdc is the ground side of the sensor.

Winfred, what year model are your drawings? My 1994 drawings show the wires exactly like your post.

Javier

[Jon K]

ground, the one with about 5 Vdc is the signal side of the sensor, the one with 0 Vdc is the ground side of the sensor.

Winfred, what year model are your drawings? My 1994 drawings show the wires exactly like your post.

Javier

Isn't the signal supposed to be 0 - 1v...

bentley says 0 - 1v VDC... i think we've got a mix up of diagrams... this is a 1992 525i M50 Motronic 3.1

[winfred]

properties says created sept 94


ground, the one with about 5 Vdc is the signal side of the sensor, the one with 0 Vdc is the ground side of the sensor.

Winfred, what year model are your drawings? My 1994 drawings show the wires exactly like your post.

Javier

[Javier]

really exchaged the wire colors!!!

Without the sensor, the open circuit voltage at the wire should go up to the source voltage wich is 5 Vdc.

Javier

[winfred]

wouldn't be the first **** up i've found on a diagram


really exchaged the wire colors!!!

Without the sensor, the open circuit voltage at the wire should go up to the source voltage wich is 5 Vdc.

Javier

[Javier]

Javier

[ryan roopnarine]

Ryan according to my Bentley PDF #70 is signal... page 130-24


i didn't check the assignment table on that page. yeah, it says 70 is input, o2s (0-1 volts fluctuating), 71 ground, o2s ground.. if you look on page 76-ewd, the actual wiring diagram picture says
71 yel
70 blk

for the rectangle labled "engine control module.

[ryan roopnarine]

im sure that the f'up is in bentley. it wouldn't make sense for the ground in a two wire pair to be colored yellow and the signal black. perhaps bill r will come by in the A.M. and break the tie definitively.

[Javier]

what color, Yellow or Black? On 92 drawings says Black, on 94 Yellow. It is very extrange that BMW decided in 93 to exchange the wire colors, so I'd bet one of them is wrong, probably the 92. Either you have a loock at the DME connector pin 70 and check the wire color, or you go further with a meter and check at the O2 sensor plug.

Javier

Edit: Jon, you can only tap the signal with a high impedance probe circuit, otherwise you will distort it and probably have a check engine warning.

[ryan roopnarine]

what color, Yellow or Black? On 92 drawings says Black, on 94 Yellow. It is very extrange that BMW decided in 93 to exchange the wire colors, so I'd bet one of them is wrong, probably the 92. Either you have a loock at the DME connector pin 70 and check the wire color, or you go further with a meter and check at the O2 sensor plug.

Javier

Edit: Jon, you can only tap the signal with a high impedance probe circuit, otherwise you will distort it and probably have a check engine warning.

oohhhhhhhh kaaayyyyyyy

did you and winfred look on model 94 year drawings? or are you saying that it was unlikely that bmw changed them in 93? cause they did. in 93, they changed from motronic 3.1 to motronic 3.3. im sure winfred knows this, so im sure his reference is probably good. the bentley looks messed up 'cause the diagram pic has different color coding than a table of pin assignments for the same model year and engine car.

[Javier]

M50 was still M3.1 at 1994, isn't it?

If you see the posted pictures, Winfred posted M3.1 1994 and I posted M3.1 1992, and they differ, think one of them is wrong.

Javier

[Jon K]

Edit: Jon, you can only tap the signal with a high impedance probe circuit, otherwise you will distort it and probably have a check engine warning.


I am tapping it with a connector and running that to my Autometer Air/Fuel ratio gauge... This is fine, correct? The gauge instructions say just tap at the ECU direct to the gauge, no issues...

[ryan roopnarine]

M50 was still M3.1 at 1994, isn't it?

If you see the posted pictures, Winfred posted M3.1 1994 and I posted M3.1 1992, and they differ, think one of them is wrong.

Javier

not quite. 1993 m50 was the m50tu, which had variable valve timing (motronic 3.3.1, not 3.3 as i said earlier). i think the only sensor changes were the addition of a knock sensors and change from hot wire mass airflow to hot film. i know my response simplifies matters greatly, but they might have had cause to swap the wires around in the changes. v8 m60 was 3.3, my bad.

[Jon K]

not quite. 1993 m50 was the m50tu, which had variable valve timing (motronic 3.3.1, not 3.3 as i said earlier). i think the only sensor changes were the addition of a knock sensors and change from hot wire mass airflow to hot film. i know my response simplifies matters greatly, but they might have had cause to swap the wires around in the changes. v8 m60 was 3.3, my bad.


My question is, im hooking up an A/F gauge.. if I accidentally (or, well, misleadingly) hook up the gauges signal wire to the ground, nothing is going to happen right? I just won't get a reading? Like I won't set my car ablaze because of using the black wire instead of the yellow or somehting stupid like that right

[Javier]

1994 drawings are M3.3.1, and actually, oxygen sensor is connected from 13 to 40, and there, signal wire is yellow.

Now I'm more confused, but probably, for 1992 Black is the signal.

Jon, don't know about that gauge, but guess the manufacturer knows what they are doing!

Javier

Edit: 93 drawings are just like 94.
Re-Edit: My drawings for M3.1 are stamped 11/92, Winfred's are 11/94, may be his include a correction on this wiring colors. Guess Jon owe us to tell what color he found to be the signal wire to pin 70!!!

[winfred]

disconnect the computer from the harness and ohm the signal wire from the 02 sensor (which is the black one) to the suspected pin/s on the computer plug, it will most likely turn out to be the yellow wire, it's possible atleast to fry the af ratio unit if hooked up to the wrong thing but i doubt that harm would come to the car. i wired up the unit built and engine turned the aluiminum mounting plate and had it working in less time that has been spent here :D
http://members.cox.net/wdixon27/gauges


My question is, im hooking up an A/F gauge.. if I accidentally (or, well, misleadingly) hook up the gauges signal wire to the ground, nothing is going to happen right? I just won't get a reading? Like I won't set my car ablaze because of using the black wire instead of the yellow or somehting stupid like that right