Shielded wire pinout

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sterlingM
Posts: 28
Joined: Sat Jan 25, 2020 9:17 am
ECU Model: S60 Pro

Shielded wire pinout

Post by sterlingM »

I've searched and read and would like to clarify on how to connect shielded cable for the crank or cam sensors. I'll mention this is my first time doing this sort of work although I'm fairly competent, bit of a learning curve with a standalone EMS harness. This is all for an S60pro

My cam sensor has 3 wires. Signal, ground, shielded ground (I think). This is going on a BMW S14 motor and using a BMW cam sensor from an S38B38 motor (e34 m5) and is a common cam sensor to use and is magnetic.

At the cam sensor plug housing: pin 1 --> signal, pin2 --> ground, pin 3 --> round and wire shield together
At the EMS plug: pin1 --> pin 22, pin 2 and pin3 and the shield from the cable are all spliced into pin 21 along with the ground and shield from my crank sensor.

Please help me confirm I've connected at the EMS side correctly or help me correct what I've done wrong. I already have the EMS powered up and speaking to my laptop, these are the final connections required (I hope) so that i can start calibrating crank and cam sensors later this week and get this to the tuner soon.

Thanks
SterlingM
katana
Posts: 385
Joined: Sun Jan 27, 2013 6:08 pm
ECU Model: S60 Pro
Firmware Version: 29

Re: Shielded wire pinout

Post by katana »

I'm no expert but inductive / mag sensors are usually two wire, Hall effect are usually three wire - are you sure its inductive?
DTA manual / wire loom diagram states the shield is left unattached at sensor end and connected to sensor ground at case only -
this applies for inductive or Hall type sensors.
sterlingM
Posts: 28
Joined: Sat Jan 25, 2020 9:17 am
ECU Model: S60 Pro

Re: Shielded wire pinout

Post by sterlingM »

Hi Katana,

Thanks for the response. The research I've done is that it's a magnetic sensor and the spinning part it senses is magnetic as well. I read that it is typically confusing because most mag sensors are two wire but the third wire in this case is for the shield.

So if I remove the shield from the sensor end and only connect at the EMS end that is a pretty easy adjustment. But the sensor still has two grounds, do I connect them both to the same pin at the EMS plug or put the shielded ground (pin 3) into the EMS pin and the other ground into the sensor ground?

Thanks
SMR
Posts: 119
Joined: Tue Jan 16, 2018 9:38 am
ECU Model: S100 Pro
Distributor: DTA
Location: Aberdeen

Re: Shielded wire pinout

Post by SMR »

Sounds right to me; I usually use a screened twisted pair cable for magnetic crank sensors - leaving the screen unconnected at the sensor end, and connected to Sensor ground (pin 21) at the ECU end - along with the actual sensor's "sensor ground" wire.
Jon K
Posts: 595
Joined: Fri Dec 04, 2009 1:45 am
ECU Model: S80 Pro
Distributor: DTA UK
Firmware Version: 73
Location: Pennsylvania, USA
Contact:

Re: Shielded wire pinout

Post by Jon K »

sterlingM wrote:Hi Katana,

Thanks for the response. The research I've done is that it's a magnetic sensor and the spinning part it senses is magnetic as well. I read that it is typically confusing because most mag sensors are two wire but the third wire in this case is for the shield.

So if I remove the shield from the sensor end and only connect at the EMS end that is a pretty easy adjustment. But the sensor still has two grounds, do I connect them both to the same pin at the EMS plug or put the shielded ground (pin 3) into the EMS pin and the other ground into the sensor ground?

Thanks
BMW VR sensors are a little confusing sometimes. By nature they'd have two wires + and -. When Ferrous metal fly past the sensor it will generate an AC signal (not DC like automotive devices would have you expect). That's why it's a + and -, not a ground. Then, the third pin is for the grounded shield. On BMW wiring harnesses the shield is actually pulled into a "pin" or cable and tied together with grounds or grounded at the ECU connector. I will see if I can snap you a photo tomorrow - I have a few harnesses in my shed. So, in the end, pull back the boot or expose the wiring at the sensor connector so you can see which pin the shield is actually going to and ground that at the ECU side. Make it easy for yourself to access your connector and re-pin it should you have to, because during my testing I have had issues with + and - on VR sensors. It's easy to wire it out of phase so it's nice when you can re-pin it when testing.

This reminds me I need to call someone back, grr totally forgot.
1992 700RWHP Pump Gas BMW
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sterlingM
Posts: 28
Joined: Sat Jan 25, 2020 9:17 am
ECU Model: S60 Pro

Re: Shielded wire pinout

Post by sterlingM »

Thanks Jon K, it's a cam sensor from an s38b38 but I'm having trouble finding a wiring diagram for it so I'm going off what I've read on other forums for the wiring pin out. It's commonly used on s14's for a cam sensor but of course few people talk about how to pin it out correctly. I bought a 3 cable shielded wire from one of the online motec stores and used that as my cam sensor cable so it's twisted pair (3 wires) and shielded 22awg wire. I could cut back the insulation where the cam sensor plug is but it's such a nice cable now that I'd rather not cut it up if I don't have to.

My crank trigger is from VAC, but its an electromotive sensor in their kit, it's exactly the same as this one:
https://electromotive.com/our-products/ ... nk-sensor/
Jon K
Posts: 595
Joined: Fri Dec 04, 2009 1:45 am
ECU Model: S80 Pro
Distributor: DTA UK
Firmware Version: 73
Location: Pennsylvania, USA
Contact:

Re: Shielded wire pinout

Post by Jon K »

sterlingM wrote:Thanks Jon K, it's a cam sensor from an s38b38 but I'm having trouble finding a wiring diagram for it so I'm going off what I've read on other forums for the wiring pin out. It's commonly used on s14's for a cam sensor but of course few people talk about how to pin it out correctly. I bought a 3 cable shielded wire from one of the online motec stores and used that as my cam sensor cable so it's twisted pair (3 wires) and shielded 22awg wire. I could cut back the insulation where the cam sensor plug is but it's such a nice cable now that I'd rather not cut it up if I don't have to.

My crank trigger is from VAC, but its an electromotive sensor in their kit, it's exactly the same as this one:
https://electromotive.com/our-products/ ... nk-sensor/
Understood - I was digging through my "spare harnesses" and found what I wanted to photograph for you. In my experience, BMW uses "black" for positive on the VR sensors (AC current). You can see that it is confirmed in the photo I attached. You can also see that they tie the other wire and the shield into a common terminal which junctions at the ECU so that the negative and shield are grounded common near the ECU. If you pull back the boot at the sensor end I would think you have a black, yellow, and shield wire (at the VR sensor connector). This allows the shield to continue up to the sensor, obviously the sensor itself only has 2 wires it provides signal over.

Image

The harness above is a Bosch Motronic 3.x from an M50TU engine, but BMW has done this same method for shielding on all models that I can tell. Note too that there are two sensor leads shown - one is for the cam and one is for the crank, that's why two silver wires are paired, etc. Hopefully it helps.
1992 700RWHP Pump Gas BMW
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