Speed meter 15% too optimistic Topic is solved

[Esperado]

I am sorry to inform-you that the previous schematic do not correspond to the printed board of my 1998 Volvo S70 T5.
The cluster block is 9148926.
The speed meter use 4 pins and is connected out of a mysterious integrated circuit YG5003B (no datasheet).
The speed meter has four pins, with two pair, each showing an impedance of 156 Ohm . I tried to add a 22 Ohm resistance in serial, hoping it was a voltmeter: No luck, no change. It is probably a steeped motor. Back to stock.

[misha]

...My tires are standard 205/50/16, and the speedometer/odometer/cruise control are working fine apart this 15%...

What was the year when Volvo switched to 205/55/16 because of customer's complaints about bent rims?
I think it was with introduction of s,v,c,xc70 models in '97(EU) and '98 for U.S market.

Speedometers are then programmed for 55 tyre profiles.

Instrument cluster can be programmed for different tyre dimensions,but it needs to be done at authorised Volvo dealer/service,and the most important thing,they need to know how to do that.
Just like only some of them knows how to retrieve the "real" mileage of the vehicle,but most of them,worldwide,doesn't know how to do that.

Also...gps readings doesn't always match with speedometer readings...well...for most of the car makes.
There is always some percent of difference where speedometer shows higher speed than gps is showing...even for a brand new,out of the factory car.

[Esperado]

Thanks misha, for your care.

...My tires are standard 205/50/16, and the speedometer/odometer/cruise control are working fine apart this 15%...

What was the year when Volvo switched to 205/55/16 because of customer's complaints about bent rims?
I think it was with introduction of s,v,c,xc70 models in '97(EU) and '98 for U.S market.
Speedometers are then programmed for 55 tyre profiles.

Anyway, the difference in tire diameters between the 205/50-16 and 195/60-15 is just 0.6%: we are far from the 15 to 20% of error I get. (I am closer to 20% compared to GPS, it is a LOT
I should add that the difference i can read between GPS and OBD is neglecting, 1 or2 kmH whatever the speed.

Instrument cluster can be programmed for different tire dimensions,but it needs to be done at authorised Volvo dealer/service,and the most important thing,they need to know how to do that.
Just like only some of them knows how to retrieve the "real" mileage of the vehicle,but most of them,worldwide,doesn't know how to do that.

Also...gps readings doesn't always match with speedometer readings...well...for most of the car makes.
There is always some percent of difference where speedometer shows higher speed than gps is showing...even for a brand new,out of the factory car.

My problem is I'm far from the <5% of the usual margin out of factory. I could live with 5%.
And, asking several, I was not able to find a Volvo dealer/service able to program-it. I have an option to do-it with my android 850OBDII application , but not working on my car.
It is incredible that I found no solution till now. And no good schematic, no wiring diagram, no help from Volvo ;-(

[misha]

Volvo diagnostic tool MUST be used here(the one which official dealers/service use)....nothing generic/universal and certainly NOT some android app.

Something is up either with your cluster or abs/tracs module.

Do you have abs/tracs light ON?

[Esperado]

Volvo diagnostic tool MUST be used here(the one which official dealers/service use)....nothing generic/universal and certainly NOT some android app.

Something is up either with your cluster or abs/tracs module.

Do you have abs/tracs light ON?

Don't be snobbish. It is just a question of reverse engineering. The diag tools of the manufacturers are overpriced in a scandalous way and the OBD tool i use works for 90% of the DTC etc... Its tire size page works for 850, not my car.
Volvo love to change everything all the mornings.

Indeed there is two possible causes of this problem: Some parasitic pulse from the ABS module that provide the speed signal, but it is improbable because the 20% error is constant whatever the speed, and the needle does not jump/shake, or bad programmation in the instrument cluster itself. I had some bad contacts in my ABS module in the past, but I fixed-it myself and it is OK now. No warning, no DTC. Everything that could be verified in the cluster itself has been verified. I just miss the schematic. or a competent and honest Volvo dealer (that will offer-me a coffee and charge me 200€ for 5 mn of work with his diag tool ?).
Easier to find a corona virus vaccine.

The other solution sould be to use some frequency divider gear, like Yellow box or SGI-100BT: Universal Speedometer and Tachometer Interface. But dunno if they works ok with Volvo cars.

[misha]

...Don't be snobbish....

I'm not...there are some things like that which requires ONLY original diagnostic tool because some modules are protected and require vehicle's or module PIN code for access and programming.

There are also some specific manufacturer's dtc which CAN'T be read with nothing else but original manufacturer's equipment.

Climate control(ECC),immo2,instrument cluster,transmission,power seats,service light reset and programming it on what mileage to turn on....those can't be accessed with nothing else but original diagnostic equipment....and certainly NOT with generic scan tools or android app.

[Esperado]

Climate control(ECC),immo2,instrument cluster,transmission,power seats,service light reset and programming it on what mileage to turn on....those can't be accessed with nothing else but original diagnostic equipment....and certainly NOT with generic scan tools or android app.

Sorry, Misha, but you are not right about-it, most of what you listed can be done with 850OBDII
https://play.google.com/store/apps/deta ... bdii&hl=fr

It is not a generic scan tool, but specialized as its name indicate. (And most of it works with my 1998 S70 T5)
I reset the service light each time I do myself an oil change. And I do can change the delay and mileage.
Too I had changed a solenoid in my automatic gear box, and the DTC was right about the one in failure, reading the gearbox codes..
So... May-be it can help some reader ? It is free and it saved-me A LOT of money.

[misha]

Ok...it seems that this is similiar to Vol-Fcr.
Vol-Fcr is excellent and works perfectly.I have it...but it also have it's limits.

But still...there are things which require a trip to a dealer.

I don't know if it is a case with this app...but most od them are advertised that can do a lot of things ...but in real life they are junk.

Does this instrument cluster tire size change works with this app?
Can it retrieve the "real" mileage?

Can it program instrument cluster...for real?Can it test the instruments?

Can it pair code keys with immo2 box?

Can it read and inspect ECC unit?It should read & clear...but can it operate the dampers of the ECC unit?

If it can...ok then,there is no need for a dealer's tool.

Just to be clear on this...i'm not a fan of dealerships too,they are called "stealership" worldwide for a reason....but sometimes and in some cases...visit to them is necessary.

[erikv11]

Definitely can use it to get real mileage but I don't know about the others, I've never messed with it.

viewtopic.php?f=40&t=83145&start=10

[Esperado]

Does this instrument cluster tire size change works with this app?

Seems yes on 850, not on S70
Can it retrieve the "real" mileage?
yes
Can it program instrument cluster...for real?Can it test the instruments?
Dunno/Yes
Can it pair code keys with immo2 box?
NO
Can it read and inspect ECC unit? It should read & clear...but can it operate the dampers of the ECC unit?
Yes/Dunno

And it can test all the components of the ABS: sensors, pump, etc...
Anyway this is out of topic and don' help.