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Link CAN lambda into factory lambda wiring


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Hi guys, 

I have an s15 link

Currently the link ecu is getting its lambda values from an Aem UEGO gauge with a bosh lsu 4.9 Via one of the inputs on the the expansion loom 

I intend to do away with this gauge and swap to a link can lambda straight to the ecu instead.

My factory lambda sensor is still connected and working, but I've been told by my mapper its totally useless and for obvious reasons. 

So, my question is:

Can the wires for the factory lambda sensor be used to wire in the link can lambda instead? 

Thanks! 

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Looks like it is a 3 wire sensor which is most likely a 12V, a switched heater ground (typically Aux 7) and the signal which is connected to An Volt 1. To repurpose these for a CAN Lambda you would use the 12V for CAN Lambda power (check that it is ign switched), cut or de-pin the An Volt 1 and Aux 7 wires at the ecu and use them for CANH and CANL and add a ground to the chassis in the engine bay for the last CAN Lambda pin. The risk with doing it this way is you could end up with a lot of noise on the CAN bus as Heater ground and signal wires aren't twisted around each other or shielded from the rest of the loom.

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10 hours ago, Vaughan said:

Looks like it is a 3 wire sensor which is most likely a 12V, a switched heater ground (typically Aux 7) and the signal which is connected to An Volt 1. To repurpose these for a CAN Lambda you would use the 12V for CAN Lambda power (check that it is ign switched), cut or de-pin the An Volt 1 and Aux 7 wires at the ecu and use them for CANH and CANL and add a ground to the chassis in the engine bay for the last CAN Lambda pin. The risk with doing it this way is you could end up with a lot of noise on the CAN bus as Heater ground and signal wires aren't twisted around each other or shielded from the rest of the loom.

Hi mate, thanks for that. 

You're right, The s15 link pinout shows:

An Volt 1 as oxy signal, so repurpose this and use this as can H for the can lambda module. 

Aux 7 as the heater ground, so I would repurpose this as can L for the can lambda module. 

Cant see the 12v anywhere on the pinout specifically for the lambda sensor. Will this just be a common 12v that everything on the loom uses?

Why would I have to cut them both at the ecu? Can these 2 inputs on the ecu not be configured to be used as a can H and L for the can lambda? Or would they now have to be wired into the expansion loom? 

When doing this can I wrap the CAN H and CANL (previously oxy signal and oxy heater) wires together to prevent interference? 

install an earth wire for the can lambda module

Does the earth need to be an ecu earth or literally just a wire from the can lambda module to the engine bay?

Apologies for needing it dummed down into simple terms, I just want to make sure I fully understand it as alot of this is new to me. 

I appreciate your time! 

Thanks, 

Adam

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On 7/3/2020 at 10:06 PM, Aseddon said:

Cant see the 12v anywhere on the pinout specifically for the lambda sensor. Will this just be a common 12v that everything on the loom uses?

Yup, will be common with ISC stuff and other 12v supplies in the loom.

 

On 7/3/2020 at 10:06 PM, Aseddon said:

Why would I have to cut them both at the ecu? Can these 2 inputs on the ecu not be configured to be used as a can H and L for the can lambda? Or would they now have to be wired into the expansion loom? 

They cannot, CAN requires special differential hardware, they would need to be wired to one of the CAN plugs on the bottom board (same plug style as the expansion loom but only 5 pins). Also I would de-pin if possible rather than cutting but either will work.

 

On 7/3/2020 at 10:06 PM, Aseddon said:

When doing this can I wrap the CAN H and CANL (previously oxy signal and oxy heater) wires together to prevent interference?

Typically they are twisted around each other  but if you are disassembling the loom enough to twist or wrap the full length you may as well as well just run a fresh pair of wires instead of reusing the O2 sensor ones.

On 7/3/2020 at 10:06 PM, Aseddon said:

Does the earth need to be an ecu earth or literally just a wire from the can lambda module to the engine bay?

Just an earth wire to the chassis, CAN uses a differential signal and so doesn't need a reference earth, this earth is for powering the CAN Lambda unit and part of that control involves putting a large amount of current through the wideband sensor heater coil and so using one of the ECU Signal earths could damage the ECU.

On 7/3/2020 at 10:06 PM, Aseddon said:

Apologies for needing it dummed down into simple terms, I just want to make sure I fully understand it as alot of this is new to me. 

No problem, happy to help.

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On 7/5/2020 at 9:43 PM, Vaughan said:

Yup, will be common with ISC stuff and other 12v supplies in the loom.

 

They cannot, CAN requires special differential hardware, they would need to be wired to one of the CAN plugs on the bottom board (same plug style as the expansion loom but only 5 pins). Also I would de-pin if possible rather than cutting but either will work.

 

Typically they are twisted around each other  but if you are disassembling the loom enough to twist or wrap the full length you may as well as well just run a fresh pair of wires instead of reusing the O2 sensor ones.

Just an earth wire to the chassis, CAN uses a differential signal and so doesn't need a reference earth, this earth is for powering the CAN Lambda unit and part of that control involves putting a large amount of current through the wideband sensor heater coil and so using one of the ECU Signal earths could damage the ECU.

No problem, happy to help.

One last thing, could the oxy heater and signal now be used for something else... Say an oil pressure sensor? Or are those 2 ports on the ecu now totally redundant? 

 

Thanks! 

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if you connect new wires to the O2 signal and heater pins then they can indeed be used as a spare An Volt and Aux respectively. But if you are going to do this you may as well add new CAN wires and reuse the existing O2 wiring for your Analog and Aux functions (unless you are using your analog and aux in the cabin in which case you don't have to run the wires through the loom to the engine bay).

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