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+--- Thread: 603 rack position sensor (/showthread.php?tid=358)
603 rack position sensor - oel_brenner - 05-11-2009
I am trying to tap into the rack sensor
on the IP to get a reference signal for "throttle" position
its working, I get the correct resistance values specified in the shop manual
25,25, and 50
and with the connector off I also get the proper ~10V off pins 1-2
What I am trying to understand is why I get no change in any value
when the rack is moved...
any ideas ?
RE: 603 rack position sensor - ForcedInduction - 05-12-2009
You can also use the cruise control actuator, its supposed to have position feedback for its controller.
RE: 603 rack position sensor - winmutt - 05-12-2009
(05-11-2009, 09:42 PM)oel_brenner its working, I get the correct resistance values specified in the shop manual
25,25, and 50
and with the connector off I also get the proper ~10V off pins 1-2
What I am trying to understand is why I get no change in any value
when the rack is moved...
Those two statements seem contrary. How are you getting resistance values and how do you know the rack is being opened?
RE: 603 rack position sensor - scottmcphee - 05-12-2009
(05-12-2009, 05:39 PM)winmutt(05-11-2009, 09:42 PM)oel_brenner its working, I get the correct resistance values specified in the shop manual
25,25, and 50
and with the connector off I also get the proper ~10V off pins 1-2
What I am trying to understand is why I get no change in any value
when the rack is moved...
Those two statements seem contrary. How are you getting resistance values and how do you know the rack is being opened?
The rack sensor is current based, and needs an amplifier to make something of it. A coil moves with respect to a magnet, or coil to coil.. anyway, that's a current device in there.
I had the same thought.. the rack sensor is only needed for the EDS idle control. It reads the ring speed and adjusts the rack to achieve a set idle.
RE: 603 rack position sensor - oel_brenner - 05-12-2009
the current is supplied by the EDS computer, on pin #2
but moving the rack via the accelerator pedal
produces no change in voltage or resistance across pins 2 and 1 or pins 2 and 3
or pins 1 or 3 and ground
engine running
or key on engine not running
tested by probing wires with connector installed
the MB manual says test procedure is measure resistance on pump
between pins and get 25 25 and 50 based on combination
and measure ~10v between pins 2 and 1 on the connector
am I just missing something stupid ?
RE: 603 rack position sensor - ForcedInduction - 05-12-2009
Check it with an inline or clamp ammeter.
RE: 603 rack position sensor - aaa - 01-20-2011
There's an entire chapter on this in the FSM... I was wandering through ps2cho's site and found section "# 07.1-1820 - Testing control rod travel sensor, MY 1986/87 (J) (USA) only ". The instructions seem to imply that the readings change depending on pressure in the ALDA. They have a table with different voltage readings depending on altitude. Readings are taken with the engine under load.
RE: 603 rack position sensor - oldbeaver - 10-16-2013
(05-12-2009, 07:00 PM)oel_brenner the current is supplied by the EDS computer, on pin #2
but moving the rack via the accelerator pedal
produces no change in voltage or resistance across pins 2 and 1 or pins 2 and 3
or pins 1 or 3 and ground
engine running
or key on engine not running
tested by probing wires with connector installed
the MB manual says test procedure is measure resistance on pump
between pins and get 25 25 and 50 based on combination
and measure ~10v between pins 2 and 1 on the connector
am I just missing something stupid ?
Dear Oel_brenner,
I am doing the same test to get some useful signal out of it, with the same result as you, so far.
Let us examine the Fuel Rack Position Sensor:
It has 3 wires that go to the EDS, in my case to pins 3, 4 and 5 of the N39. One wire is yellow, one is blue and one is Brown/black.
The issue here is to measure all three and see id one of them variates following the throttle. If they all do not variate, what info can they feed to the EDS?
I tested only the blue wire with respect to earth. Maybe you did the same? Now I will test the potential between each pair combination and between each of the tree and earth.
What are you trying to do? Lets Exchange our experiences.
Oldbeaver
RE: 603 rack position sensor - Tito - 10-16-2013
The sensor works different than normal 0-12v/5v sensors I guess
I have never ever seen one but I think it works with a coil, where a iron is inserted into when the rack travels to full?
This means that the "induction resistance" (don't know the English word) is bigger and it takes more time to "charge" the coil. That would explain the 10v connection (duty-cycle or pwm power input) , for every time the coil charges. The time the coil takes to charge to full is measured by the eds.
I'm hoping I it's clear. My technical English isn't that good but I'll be happy to explain further if it's not the copper-brush type sensor.
Edit: this type of sensor:
![[Image: Rack3.jpg]](http://i128.photobucket.com/albums/p169/turbo617/MercedesForum/Rack3.jpg)
RE: 603 rack position sensor - raysorenson - 10-16-2013
Br/Bk should be ground. Feed the voltage into either of the 2 other wires and measure travel with the 3rd.
RE: 603 rack position sensor - oldbeaver - 10-16-2013
(10-16-2013, 12:51 PM)Tito The sensor works different than normal 0-12v/5v sensors I guess
I have never ever seen one but I think it works with a coil, where a iron is inserted into when the rack travels to full?
This means that the "induction resistance" (don't know the English word) is bigger and it takes more time to "charge" the coil. That would explain the 10v connection (duty-cycle or pwm power input) , for every time the coil charges. The time the coil takes to charge to full is measured by the eds.
I'm hoping I it's clear. My technical English isn't that good but I'll be happy to explain further if it's not the copper-brush type sensor.
Edit: this type of sensor:
Thank you much. Yr English is perfect for me. I have some documents and will check what kind it is. What I would like to learn is what kind of signal this device sends to the EDS. This is important for intercepting it.
Oldbeaver
(10-16-2013, 01:29 PM)raysorenson Br/Bk should be ground. Feed the voltage into either of the 2 other wires and measure travel with the 3rd.
Thank you much for yr advice. I will check what happens this way.
Will be posting my findings to the Fórum.
Oldbeaver
PD:
RE: 603 rack position sensor - Tito - 10-17-2013
Do you have a electric diagram and a picture of the sensor? Can't find anything online.
RE: 603 rack position sensor - oldbeaver - 11-21-2013
(01-20-2011, 04:51 PM)aaa There's an entire chapter on this in the FSM... I was wandering through ps2cho's site and found section "# 07.1-1820 - Testing control rod travel sensor, MY 1986/87 (J) (USA) only ". The instructions seem to imply that the readings change depending on pressure in the ALDA. They have a table with different voltage readings depending on altitude. Readings are taken with the engine under load.
Dear AAA: Can you please tell what is that "FSM" place where there is an entire chapter on the issue? What does "FSM" states for?
Excuse my ignorance, it is only overcome by my interest.
Thank you,
OldBeaver
RE: 603 rack position sensor - larsalan - 11-21-2013
He means
Factory
Service
Manual
RE: 603 rack position sensor - oldbeaver - 11-21-2013
(11-21-2013, 04:13 PM)larsalan He means
Factory
Service
Manual
Thank you much.
OldBeaver
RE: 603 rack position sensor - barrote - 03-26-2015
hy ,
so did u get some more info on that ?
to me it does not look like feeding current wont work!!!
i´m very interested in discover how it does work , and what shifts
regards
RE: 603 rack position sensor - oldbeaver - 03-27-2015
(03-26-2015, 06:25 PM)barrote hy ,
so did u get some more info on that ?
to me it does not look like feeding current wont work!!!
i´m very interested in discover how it does work , and what shifts
regards
Unfortunately not.
I will investigate other way to get an estimation of real time fuel consumption, hope to upload results here.
Oldbeaver.
RE: 603 rack position sensor - barrote - 03-31-2015
yep
my bad. a friend of mine, he´s avionics tecnician, told me something about two coils, diference in charging time between coils, what i dont understand is why MB made the sensor like that.
MB engeneers use to be more old timmers like, simple and perfect. thats why
anyhow i´ll investigate two , and if i can figuer out something i´ll let u know.
regards
RE: 603 rack position sensor - raysorenson - 03-31-2015
Linear variable differential transformer
http://en.wikipedia.org/wiki/Linear_variable_differential_transformer and this http://forum.arduino.cc/index.php?topic=183366.0
Fresh keywords if your search is going stale :-)
RE: 603 rack position sensor - barrote - 04-01-2015
yes that can be ..... wich wire u feed and wich tension? i tried it against 3/4 volt range and got no feedback diff.
this is what i was wondering about german engeners. a robust device easy to operate.
thanks
RE: 603 rack position sensor - raysorenson - 04-01-2015
I'm wondering if this LVDT uses alternating current or DC. I'll see if I can find time to hook the o-scope up to my 603 this week.
RE: 603 rack position sensor - barrote - 04-01-2015
hy ray,
well if its inductance based must be AC type. but this ussually works with a series fitted oscilator for primary coil, something easy to achieve. and the end result is DC. the secondary coil.
i´m after the rack position sensor on the EDC pump, wich is basically the same as the M´s or mw´s. being the purpose diff.
it would be interesting to know your findings, cause i dont own a scope, nor i have much expertise on it, my exp is the mechanics
hugs
RE: 603 rack position sensor - baldur - 04-02-2015
(03-31-2015, 05:07 PM)raysorenson Linear variable differential transformer
http://en.wikipedia.org/wiki/Linear_variable_differential_transformer and this http://forum.arduino.cc/index.php?topic=183366.0
Fresh keywords if your search is going stale :-)
Yeah except there is almost no signal coupling between the two coils. This is a variable inductance coil, not a transformer.
Also, the inductance of any inductor varies a lot by temperature, so there is a second coil that is on a fixed core and used for reference.
RE: 603 rack position sensor - barrote - 04-02-2015
yep inductance resistance , matters few.
do u happen to know of a easy way of mesure the position ? and variation on the position? that´s what we are after....
regards
RE: 603 rack position sensor - raysorenson - 04-02-2015
Looks like olefejer has already shared a schematic. He used 10khz just like the guy on the arduino board used.
http://dmn.kuulalaakeri.org/tmp/olefejer_hdk.jpg
video
https://www.youtube.com/watch?v=BTDwsjy3RuI
RE: 603 rack position sensor - Petar - 04-02-2015
That schematic is very unclear though. What is that IC, which pin goes where ?
Olefejer is on the forum, hopefully he can shed some light on the subject.
RE: 603 rack position sensor - barrote - 04-03-2015
that is too complicated to my needs.
later on i´ll solve the matter, then i´ll keep u posted
RE: 603 rack position sensor - Petar - 04-03-2015
One idea i had was to have two LC oscillators whose inductance would be the signal coil and the reference coil respectively. Then the output would be converted to square wave whose frequency would vary with inductance. Measure that frequency and calculate the inductance from that. Make reference coil based adjusment in the software.
RE: 603 rack position sensor - baldur - 04-03-2015
(04-03-2015, 04:39 PM)Petar One idea i had was to have two LC oscillators whose inductance would be the signal coil and the reference coil respectively. Then the output would be converted to square wave whose frequency would vary with inductance. Measure that frequency and calculate the inductance from that. Make reference coil based adjusment in the software.
Yes that'll work.