G251 Sensor

Ronin225 · Mar 25, 2012

Just been asked about a part of the S3 and had a look on the web and appears these longitudinal sensor is only on the 4 wheel drive leons
Can anyone confirm this for me?
Does the 2WD LCR have this sensor for its ESP system or will i need to transfer this from the S3?

Allan_84 · Mar 25, 2012

if you have ESP you have 2 sensors

one measures the transverse acceleration forces, the other one measures the longitudinal acceleration forces.

Ronin225 · Mar 25, 2012

Yes have ESP, but can only find reference to them on haldex setup cars.
Its too dark to go outside to check but i'm assuming the position should be the same as the s3
One sensor under the steering column and the other behind the glovebox on the end of the dash.
This seems to have control over the activation of the haldex though.
I will try and get time to have a look tomorrow

Allan_84 · Mar 26, 2012

in etka i can see both "front-w.drive" and "LEON 4" having both sensor. there is some change in 2002. and some of them have one unit with both sensors in the same box i think.

rhd (right hand drive) leon options for front-w.drive (FWD) up to win number: 1M-2-063 000
1J2 907 639 ---> acc.sensor
1J0 907 657 B ---> yaw. sensor

rhd (right hand drive) leon options for front-w.drive (FWD) from win number: 1M-2-063 001
1j2 907 637 G ----> combi sensor with both acc. and yaw sensor

rhd (right hand drive) leon options for LEON 4 (4wd haldex):
1J2 907 639 ---> acc.sensor
1J0 907 657 B ---> yaw. sensor

Ronin225 · Mar 26, 2012

Cheers, i will have to check if i have two sensors or one.
Seeing that the change is in 2002 this could be a revision for the cupra R as some early well specced cupras have ESP too.
Mine is a late 2005 leon so would assume i would have the last revision so probably one combined sensor
If a combined sensor i assume it would be located under the steering column too

Muttley · Mar 26, 2012

With ESP you should have sensors for lateral acceleration (G200), yaw rate (G202) and steering angle (G85). Elsawin says that the longitudinal acceleration sensor (G251) is only fitted to 4-wheel drive models with the Haldex system.

G200 and G202 are both fitted at the bottom of the steering column. It appears that some cars have a single sensor package (G419) in the same location which contains G200, G202 and G251 but in a single smaller box.

A number of high-end cars have ESP and it was an option on all cars, I think. My Toledo TDI 150 Sport has it, for example.

Ronin225 · Mar 26, 2012

Muttley said:
With ESP you should have sensors for lateral acceleration (G200), yaw rate (G202) and steering angle (G85). Elsawin says that the longitudinal acceleration sensor (G251) is only fitted to 4-wheel drive models with the Haldex system.

G200 and G202 are both fitted at the bottom of the steering column. It appears that some cars have a single sensor package (G419) in the same location which contains G200, G202 and G251 but in a single smaller box.

A number of high-end cars have ESP and it was an option on all cars, I think. My Toledo TDI 150 Sport has it, for example.

This is what i was finding only haldex equipped cars had G251 which makes me wonder if it activates the haldex pump to take drive to rear diff to use it to brake instead of using an individual caliper?
Does Elsawin list a part number for G419 as i should have G200 and G202 as the LCR comes with ESP standard
Just digging through a pic from when i did my brake light switch but i see relay 409 which after a search appears to be the fuel pump and the cover above that i didnt remove would probably house the sensors

grahams81 · Mar 26, 2012

Ronin225 said:
which makes me wonder if it activates the haldex pump to take drive to rear diff QUOTE]

Tim, the system doesn't use an ecu in the car to then send a simple signal to the diff to lock.
The controller that decides on the locking / etc is built in to the diff....the haldex controller -

It is an electro / hydraulic controller, the actual controller works out when to lock by the information its supplied.
The information comes via the communication system called "canbus" and will have all the data in from varies sensors etc.

Here's what im using -

http://www.sqsracing.com/files/fs_files/productdetails/406/assembly-manual-mhr-mhrb_47.pdf

Ronin225 · Mar 26, 2012

I Know the haldex controller controls the actual pump itself but wonder if the this sensor relays info to the ESP unit which in turn speaks to the haldex controller telling it to engage
On the OE system the haldex unit can also engage to enhance braking i wondered if it was using this to control the stability of the car too.
I will be looking into these SQS units as this looks to be a much much easier option than trying to imitate the S3's system and transfering parts to suit

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G251 Sensor

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