S90 2 years of shifting problem

Post by **jimmy57** » 25 Dec 2012, 13:22

They changed the reference voltage but those are good numbers. The TCM knows you have selected E or S by the voltage being grounded by switch and being 0V.
Connect 1 and 3 and drive and see if it behaves as it should.

vova · Post by **vova** » 25 Dec 2012, 19:12

so 10V is ok, i thought i found a problem voltage not being 5V.
i connected 1 and 3 but shifting problem didnt go away. also tried 2 and 3 no change same shifting problem.

what i also have noticed that putting gas pedal to the floor (taking off fast) gives no shifting problem.
also driving in W mode no problem but W is within one gear (no shifting).

if this was mechanical transmission problem i would have killed tranny in 2 years.

what would you suggest?

Post by **jimmy57** » 25 Dec 2012, 21:49

N ow it gets serious. The speed signals need to be read with a scan tool. Erroneous vehicle speed sensor inputs make the TCM do what the speed signal would indicate. If you depress pedal and close the kickdown switch it will hold the low gear until the max program speed for that gear.

vova · Post by **vova** » 26 Dec 2012, 07:43

Do you mean speed sensor on the transmission or some other speed sensor?
Would you know where speed sensor located on my car?
Scan tool, do mean the one dealer would have? To scan trasmission i had to go a delaer since this vehicle and year noone has a scan tool to do a trasmission only a dealer.

How else can a speed sensor be checked?

I have another TCU box used. Can i replace existing one just to see how it would drive?
Is it a plug in device no programming required? someone told me that 1998 volvos no programming requires.
Can i damage vehicle with another TCU box?

If kickdown switch closes too earler, what happens? I suspect kickdown switch may be a problem, will check with Ohmmeter.

thanks

Post by **jimmy57** » 26 Dec 2012, 08:10

The speedometer supplies the speed signal to the TCM. If the speedo needle is stable when this is happening then it is unlikely to be the speed sensor on rear diff unit but is more likely the speedometer failing in its conversion of the sensor input to the digital output to the TCM. DOes the cruise control work OK? it uses a digital output from the speedo also.

You can try another TCM but I doubt it fixes it. It requires no programming and will do no harm.
Forget the kickdown switch, it is for downshifts for passing and is triggered only when you go full throttle.

Independent volvo shops around here have scan tools that can read volvos, I bet there is one around you.

vova · Post by **vova** » 26 Dec 2012, 10:37

speed needle is steady, cruise works fine everytime. if i floor it there no shifting problem.

as you know S90 has no kickdown cable, there is a switch by the wall with a gas cable going thru it.
What if this switch stays closed due its age (this is electro/mechanical device), if it stays closed breifly as i am accelerating it sends a signal to the transmission to kickdown a gear. is this possible?

i did scan transmission once 3 weeks ago and 114 was the only code as i mentioned before.

thanks

Post by **jimmy57** » 26 Dec 2012, 12:30

You can unplug the KD switch at cable under hood to eliminate that.
I was talking about live data readout with a scan tool to see if the speed signal is legitimate.

vova · Post by **vova** » 26 Dec 2012, 19:42

is live data read from obdii connector? how is it done?

gmtgmt · Post by **gmtgmt** » 30 Dec 2012, 09:52

you need a scan tool that can read live data.

Also fix the vacume leak i have had this problem with my 1991 960. this was the problem.

vova · Post by **vova** » 01 Jan 2013, 21:18

I didnt do scanning yet
I ve been having a problem with ignition switch for sometime. Everytime i start i need to jiggle key to have lights. So i replaced ignition switch also thinking that it supplies power to TCU and may cause improper voltage.
OMG problem solved...........drove for a few minutes stop signs, traffic lights, stop ang go....shifts very smoothly like new.

...but once it warms up it started doing same thing as before. it is 30-35 degrees here in NYC so while it is cold it shifts fine once it warms up it does what it is been doing for 2 years.

it is gonna be cold for a few days so i ll monitor next few days if outside temperature has indeed affect shifting.

is there connection between outdoor temperature and vacuum leak when it comes to shifting??? if not so what outdoor temp does to shifting?
thanks

S90 2 years of shifting problem

Re: S90 2 years of shifting problem