Fix one thing , break another - P1875

[fixkick]

in the net
the TCM and ECU must be happy here,
and THEY DO talk to each other that is for sure, and they must like what each other sees.
or hell to pay. DTC. and fail smog.
no URL link to reduction box posted nor SKU or full name and model of said reduction box. be nice to know that too.
and reductions is wrong for offroad huge tires. unstated, them.

but reduction would be correct for dinky do, tiny lowerider tires. tiny tires spin faster, lower circum..

[fixkick]

if this helps he G16 reed is here. (the 1.8 may look the same but  Sport speedos are rear to find and even harder seen like mine)

unscrewed here and jacked up and not now next to inside magnet. IT is cave man simple. a simple switch (mag)  the worm gear is for ODOMeter.



4AT, 4wd







finding this sensor to buy is super hard, most top stores have none. (remove it and clean the tip of mud there is 1st thing 1st act) if you suspect it.
suzuki only sensor. I THINK.  1992 to 1998 are the same if 4wd.  2wd sensors are no good at all here, as 2wd runs a gear on end.
24791-57B00 ,

research on this sensor shows,  fits 2wd 2005 Grand vitara, |SQ625 (v6) USA
2wd  tail shaft housing has 2 sensors, right side gear and left mag sensor,  same exact part as yours. (found by accident)
the 2005 4wd the sensor is same but located on left side of extension housing  same P/n.  57b00
so that is the most new car made that uses this sensor. and super hard to find and buy...




there  I both posted, in photo form. clearly.

[thebanjoman]

I am still STUCK at tires SIZE why leave off such a very important fact.
endless tires made, endless rims,  I can not at all guess what tires and rims are on this car ever.
and would be nice to know, for sure,  at post 1 for sure.
virtual signature 1:
1998 sport, 4wd, 4AT, 4door, 2.3L new engine + UNKNOWN TIRES AND RIMS. (1.8L ECU and 1.8L TCM stock sill there)

You are correct.

[quote pid='12563' dateline='1580652999']
1998 sport, 4wd, 4AT, 4door, 2.3L new engine + P245/75R16 Tires (1.8L ECU and 1.8L TCM stock sill there)
[/quote]


I went from the Stock tires to P245/75R16 which is about 13% larger.

I used the term 'reduction box' incorrectly.  This is what I used.

https://www.ihpartsamerica.com/store/SPE...ARBOX.html    Not from the same manufacturer but this is a picture of what I am using (removed now) .


With the box in place, speedo reading 70.  GPS says Im going 70.   (and of course P1875 codes. It is not immediate but eventually will throw the codes) 

Probably should address this at the speedo sensor than the transmission sensor as it's probably going to be easier to solve

If I can grab the VSS signal from the speedo with the arduino, change it and sent it to the ECU at the difference I MIGHT be able to solve this.

I guess I am also 'mixed up' in the direction I need to go with this.   13% high or 13% low to get it back so the 4AT trans VSS happy as to me. 

I have a 1998 FSM and can copy and upload the relevant pages.

I have not played with an arduino but from my reading I think one could be used to make the changes needed.

[fixkick]

hope we are not chasing Phantoms here, I have no 1998 sport manual,
i have library of factory FSM books here, PDF on all suzuki and tracker up to 2004
all everyone that has P1875 shows DTC P1875 4L Switch Circuit Malfunction (Open)
every one.
but the SPORT can be different as P1 is a factory ONLY code and only a correct matching manual is the truth and sorry I do not have this one manual.
I think you said you had the sport manual. so.... but I forget./

[thebanjoman]

hope we are not chasing Phantoms here, I have no 1998 sport manual,
i have library of factory FSM books here, PDF on all suzuki and tracker up to 2004
all everyone that has P1875 shows  DTC P1875 4L Switch Circuit Malfunction (Open)
every one.
but the SPORT can be different as P1 is a factory ONLY code and only a correct matching manual is the truth and sorry I do not have this one manual.
I think you said you had the sport manual. so.... but I forget./

 1998 Sidekick  1600/1800/x90  Wiring Diagram Manual   - 99512-60A70-33E
 1998 Sidekick 1800 Supplementary Service Manual 1800  - 99501-61A70-33E

Are the books I have.     The 1800 Supplement - Page 7B1-43 and 7B1-44  P1875 4WD Low switch circuit malfunction 
 7B1-43  states the difference of more than 10% between trans VSS and Speedo VSS
 7B1-44  Troubleshooting the switch.  test continuity between E172-18 and ground (disconnected PCM) followed flowchart of tests - ALL GOOD

 My tests. 

  2Hi and 4Hi - it is infinity
  4Lo  - There is continuity 
  I purchase and installed NEW 4Lo Switch and performed tests again - SAME

 I can scan the pages and upload them to you if need be.

 If I have the aftermarket speedo gearbox on the cable -  P1875 codes are generated randomlyu
 If I remove the aftermarket speedo gearbox on the cable - NO P1875 codes

 So I believe the condition I am experiencing is from Page 7B1-43  differences between speed sensors

[fixkick]

I am still STUCK at tires SIZE why leave off such a very important fact.
endless tires made, endless rims,  I can not at all guess what tires and rims are on this car ever.
and would be nice to know, for sure,  at post 1 for sure.
virtual signature 1:
1998 sport, 4wd, 4AT, 4door, 2.3L new engine + UNKNOWN TIRES AND RIMS. (1.8L ECU and 1.8L TCM stock sill there)

You are correct.

[quote pid='12563' dateline='1580652999']
1998 sport, 4wd, 4AT, 4door, 2.3L new engine + P245/75R16 Tires (1.8L ECU and 1.8L TCM stock sill there)

I went from the Stock tires to P245/75R16 which is about 13% larger.

I used the term 'reduction box' incorrectly.  This is what I used.

https://www.ihpartsamerica.com/store/SPE...ARBOX.html    Not from the same manufacturer but this is a picture of what I am using (removed now) .


With the box in place, speedo reading 70.  GPS says Im going 70.   (and of course P1875 codes. It is not immediate but eventually will throw the codes) 

Probably should address this at the speedo sensor than the transmission sensor as it's probably going to be easier to solve

If I can grab the VSS signal from the speedo with the arduino, change it and sent it to the ECU at the difference I MIGHT be able to solve this.

I guess I am also 'mixed up' in the direction I need to go with this.   13% high or 13% low to get it back so the 4AT trans VSS happy as to me. 

I have a 1998 FSM and can copy and upload the relevant pages. ( just the one line for P1875 , i think you did show this already and is UNIQUE on THIS CAR)

I have not played with an arduino but from my reading I think one could be used to make the changes needed.
[/quote]

THANKS FOR SHARING your cable box, (gear box device) !!!


its ok, and I see now the maker of the (cable box) does not show part numbers so is unknown. but you checked the speedo and for sure the needle reads 70mph hour now so the cable box is correct but not the VSS1 output, it is running slow.
both VSS must read correctly (about)


you need this electronics, (only 2 ways to do that) there are no gears on the end of VSS1, at all. it is coil sensor 2 wire and non hall sensor and is  big pain that. more later.
CPU
or Analog.

VSS1(4AT) >>> zero crossing detector >>>>to CPU,>>> some software scaling and then send out faster square wave at say 2vdc to TCM.
then analog.
way.
VSS1(4AT) >>> zero crossing detector >>>>to FVCO to (a 10% gain op.amp to a VFCO to TCM.  (hard to do lots of parts)

be best to make a frequency to voltage converter followed by a voltage to frequency converter.
because the frequency is so low, it would be cheaper as far as parts count to just hook up a zero crossing detector to a micro controller and use a lookup table to generate the sine wave from PWM.
Youd need look up table for all speeds,  from 1mph to 120MPH or at least to what is max speed on your car, IDK.  100 should do it.
the granularity of the table only needs to be inside your (10km/m window)

10kph= 6.213712mph so make the table at every 5mph.  X axis ,  20 speeds, mph 0, 5, 10 ,15 ... up. to 100
then in each cell (and array it is called) we lay down perfect vss click speeds that I DO NOT KNOW ON THIS CAR. Speedo we do but in not same.
the software would measure VSS1 speed (in HZ) and then using that speed inputted use that to index the above data array and then output  that HZ to your CPU output port
called VSS out to TCM.  2 to 5v output will work and is a perfect square wave,  and is 13% faster all the time, 1MPH up.


The hard part is getting the arduino to measure the vss1 input,  and creating a number (integer) from 1 to 20.
the array is simple
the output too, is kinda simple using the Arduno internal clock timers, sending table data to them get you the output you want.

The advice I have  on the MEASUREMENT algorithm is to  , use interrupts,    the this routine will be dead, and each VSS1 input positive going edge, from the  zero crossing detector
would fire off the  interrupt code, each edge and be counted for HZ input. timed)
then the count scaled (VSS1 I do not know its rules) and output as 20 speeds.

the zerocrossing detector is mandatory, this device, can read the very tiny 1v and weak coil voltages.  and output a prefect say 5vdc square wave.

then that prefect square wave, is sent to the CPU (arduino)





the chips that can do the analog method are here.
https://www.globalspec.com/learnmore/sem...rter_chips

A LM2917 frequency to voltage converter chip is a monolithic to voltage converter and is used in cruise control and speedometer applications

https://www.ti.com/lit/ds/symlink/lm2907-n.pdf
see this, 
this is voltage and we then run that to a 110% gain Op. amp,  gain of 1:1.1  1volt in 1.1 volt out,
then from there to a VFC (the reverse of the above..

same place 360 eng.
https://www.globalspec.com/learnmore/sem...rter_chips

this is the reverse act. V to F. the AD7740 can do this. (your design is low frequency easy)
https://www.analog.com/en/products/ad774...t-overview

https://www.analog.com/media/en/technica...AD7740.pdf

the clock pin is the only tricky part,  Fclock-in  needs be at what ever is VSS1 Hz is at 100mph. IDK this, what Id do is measure VSS1 ouput put HZ at 10mph and 10x that or times 110%
there are clock gen chips made now today that make crystals obsolete. (ever order a custom crystal in 2020, oops they went out of business most did)
you could in fact make the OP amp in the center with a POT to set (OP.AMP) gain from 1 to 20% and now works with any tires made.
or even use $10 LCD frequency counter that can monitor output and show it on the box you make.



I can only see that the 03-72LE output shaft has this (photos blury) tone wheel in the transmission tail with may be 8 vanes ? no 4,
so if true that the output of VSS would be 4 pulses per RPM of tail shaft.. and that be 5.12 times lower RPM of the rear axles, and tire circumference be speed.(distance per turn)

but also no tone wheel in had to tell this. (suzuki secret solved) but at 10mph with a scope at VSS1 pins we see that easy.

those are my ideas.  done 2 ways, , hope it makes sense , I will edit it more times later get it better.


off my gears page the 5.12 rear axles turn 744 times per mile. stock tires. USA.


P205-75-R15

744/760 (the 2 axles used does this,
85.1 inches circum stock.

the prop shaft at 60mph stock turns at. 145.3 turns per mile.  (5.12 axle gears) (stock tires)
so if the tone wheel has  4 vanes it does  581 clicks per mile.   at 60mPH  that is one mile per minute and 581 clicks a minute, and that be ~10clicks a second, (or 10 HZ)

if my math works out.   (this signals are tiny as low as 1v and slow, slow is good, easier design using cheap chips,


OK found a video on installing VSS1 tone wheel, it is 4 vanes so is 1/2 what I said above. 


ah here is the tone wheel, special thanks go to Frank Cook !!!, for OMG wow full 4AT transmission rebuilt video, 23 chapters long. this is 4wd only example

[fixkick]

recap VSS1, 4 pulses per turn of PROP shaft. (the secret told due to above 1 photo)
The tire wheel axle turns 744 turns per mile on stock P205-75-r15) USA spec, car.
the prop shaft turns 5.12 times that, faster. at 3809 turns per mile and tone wheel does 4 times that. 15,237 clicks per mile.

so at 60MPH that this 60x that 914,227 clicks per hour.
to compute that to Hz (pulses per second (leading edge) divide that by 60x60 or 120, (min x seconds) = 7618 Hz, or pulses per second. at 60MPH.
the scaling at 60MPH corrected with the black box would be 110% more is 8380 HZ out.

the problem to make a box is lacking a live signal to test, and debug. a trans on a bench and drill motor turning trail shaft would work but is too OVER THE TOP hard.

what I'd do is get a hobby box with zero crossing detector inside, with power, from say 12vdc to 7805 REG (temporary this there are vastly better regulators for car ) to 5vdc
then connect box to car and VSS1, and make sure the zero detector works , I use the free ZD, in the above posted chip, LM2917 . nice chip that is.
then with that working, make the other side that scale Vout from LM2916 to your VFC chip. scaled at 110% and tuned by you.

or use Arduino way.
a coding 99% exercise. (+ ZCD )

[fixkick]

Arduino, + ZCD , zero crossing detector is a must for VR coil sensors (most) as the signal  are tiny for sure low speed. of car. (a HALL sensor would be cake walk )

here is one example of the first part of the job, measuring frequency.

the next stop is scale up this new Freq. by 113% just using math.
freq-out = freq x 1.13  (now 13% more)
the set timer to freq-out


google how to use  Arudio to output a timer clock you control. (using freq-out)
and send it to a pin and connect that pin to VSS pin on TCM.

now the bad news, no spec on TCM
if lucky at least one pin might be ground and 2nd is input to TCM, vss1.

at the worse Ive done this and used transformer to emulate the VR sensor into TCM.
a 1:1 turns ratio transformer very very tiny one, 600ohms  rated, for audio work;.
I did the once to fool a FORD ECM to like my fake CRANK CKP sensor.

the VSS1 pins on the TCM
are not documented. pin # and color are, but not how TCM processes those pins, but in most cases is a ZCD in the TCM,   .

[thebanjoman]

Arduino, + ZCD , zero crossing detector is a must for VR coil sensors (most) as the signal  are tiny for sure low speed. of car. (a HALL sensor would be cake walk )

here is one example of the first part of the job, measuring frequency.

the next stop is scale up this new Freq. by 113% just using math.
freq-out = freq x 1.13  (now 13% more)
the set timer to freq-out


google how to use  Arudio to output a timer clock you control. (using freq-out)
and send it to a pin and connect that pin to VSS pin on TCM.

now the bad news, no spec on TCM
if lucky at least one pin might be ground and 2nd is input to TCM, vss1.

at the worse Ive done this and used transformer to emulate the VR sensor into TCM.
a 1:1 turns ratio transformer very very tiny one, 600ohms  rated, for audio work;.
I did the once to fool a FORD ECM to like my fake CRANK CKP sensor.

the VSS1 pins on the TCM
are not documented. pin # and color are, but not how TCM processes those pins, but in most cases is a ZCD in the TCM,   .

 Making changes at the trans speed sensor seems way above my skill level.

 Couldn't I make my adjustments on the speedometer side as that's what I am changing with my gear box device ?  

 Read the reed valve pulses and reduce them by 13%    ??

[fixkick]

Arduino, + ZCD , zero crossing detector is a must for VR coil sensors (most) as the signal  are tiny for sure low speed. of car. (a HALL sensor would be cake walk )

here is one example of the first part of the job, measuring frequency.

the next stop is scale up this new Freq. by 113% just using math.
freq-out = freq x 1.13  (now 13% more)
the set timer to freq-out


google how to use  Arudio to output a timer clock you control. (using freq-out)
and send it to a pin and connect that pin to VSS pin on TCM.

now the bad news, no spec on TCM
if lucky at least one pin might be ground and 2nd is input to TCM, vss1.

at the worse Ive done this and used transformer to emulate the VR sensor into TCM.
a 1:1 turns ratio transformer very very tiny one, 600ohms  rated, for audio work;.
I did the once to fool a FORD ECM to like my fake CRANK CKP sensor.

the VSS1 pins on the TCM
are not documented. pin # and color are, but not how TCM processes those pins, but in most cases is a ZCD in the TCM,   .

 Making changes at the trans speed sensor seems way above my skill level.

 Couldn't I make my adjustments on the speedometer side as that's what I am changing with my gear box device ?  

 Read the reed valve pulses and reduce them by 13%    ??

The speedometer is cable driven, and the suzuki parts used to have great sets to fit many head.
for different axle ratios used world wide. is the purpose.
that is G16 car
the J18, only has 1 gear set (plastic) for  only the one axle there are no other gear sets for the VSS2 cable drive to the cluster.
the SPORT is only sold in USA /Canada and Puerto Rico . MPH and KMH and use the same ratio drive, all. on the cable.  so there is no suzuki cure here, like G16s

you did it the only way on earth possible at the cable, a gear up box. it is. on the cable
VSS1 is not mechanical at all, it is electromagnetic, and  a pulse, only that is all it is. for speed.


There are only 2 VSS1 cures,  one is Analog electronics and other is digital processing and using some kind of re-scaling methods.

the reason nobody I know makes this is because, there are so many sensor types and worse so many TCMs.


here is what a 2 wire VR mag sensor looks like very small signal