Moderators BarManBean Posted January 1, 2014 Moderators Posted January 1, 2014 Anyone know how I can get my speedometer to read correct again after switching to LGT-sized tires on my OBXT? A couple things going through my head are the speed sensor (is this in the driver-front wheel area?) and the ECU. Not sure what else would be different on an outback compared to a legacy and also affect the speedometer. I'd like to start comparing some part numbers, but honestly don't quite know what to even search for. "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock
rob-2 Posted January 1, 2014 Posted January 1, 2014 On other cars you can buy a yellow box that goes between the ecu and tranny sensors to allow you to adjust the ecu input.
iNVAR Posted January 1, 2014 Posted January 1, 2014 It's been stated by SBT that: http://legacygt.com/forums/showpost.php?p=4655121&postcount=42 It is the wheel sensors and their signal to the ABS Control Module that drive the speedometer, not something from the transmission.
Moderators BarManBean Posted January 1, 2014 Author Moderators Posted January 1, 2014 I did know that our transmissions don't have a speed sensor in them and that it has something to do with the wheel sensor(s). I would imaging that it's only based on *one* wheel sensor though, doesn't seem like it would be helpful to have four signals for the speedometer. And either way, SOMETHING is different between a legacy vs. an outback that results in the speedometer reading differently--I'm just trying to figure out what that is: wheel sensor, ECU, cluster, all of the above...? "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock
xt2005bonbon Posted January 2, 2014 Posted January 2, 2014 My guess would be ECU. The ECU may be doing a simple math operation to convert the wheel sensor signal into MPH. It *may* be a simple variable change in the math. I wonder if you'd get some help over on the romraider forum.
ehsnils Posted January 2, 2014 Posted January 2, 2014 Either the ECM or the ABS/VCD ECU provides the speed.
xt2005bonbon Posted January 2, 2014 Posted January 2, 2014 Looks like all the work is done within the ABS module and it also uses all four wheels input..speedometer.pdf
ehsnils Posted January 2, 2014 Posted January 2, 2014 In that case there's probably a parameter to adjust in the ABS ECU. And to do that you will at least need the Subaru Select Monitor, or possibly a manufacturer tool unless you actually need a different ABS unit.
Moderators BarManBean Posted January 2, 2014 Author Moderators Posted January 2, 2014 Best I can tell from opposed forces, the ABS sensors are the same. I'll poke around some more in that direction though, thanks. "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock
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