Speed sensor calibration after tire change

[kane67]

Hi,

Has someone done after changing bigger tires?
Manual says there's a "speed sensor calibrator" module behind instrument panel storage compartment, what needs to changed if axle ratio or tire size is changed.

But, is possible to reprogram etc.by using Tech Tool???

[jifaire]

Hi,

Has someone done after changing bigger tires?
Manual says there's a "speed sensor calibrator" module behind instrument panel storage compartment, what needs to changed if axle ratio or tire size is changed.

But, is possible to reprogram etc.by using Tech Tool???

Nope. The VSSB/DRAC (VSSB = Vehicle Speed Sensor Board, DRAC = Digital Ratio Adapter Controller ... who comes up with these?) is mounted behind the glove compartment, and changing it requires some soldering and playing around. Most people solder in a set of DIP switches so that they only have to do this once.

Since this is a manual setting, it cannot be done with a Tech-II or other scan tool.

Check out the link to fix yours:
http://www.tbichips.com/drac/

Jim

PS - mine is out-to-lunch, too; I changed a 4.10 to a 3.73 for mileage/longevity. However, that's a 10% change, and it's easier to convert that one in your head than solder a DRAC, so I didn't bother.

If you really want this done, but don't want to do it yourself, I'm sure GM would be happy to sell you a different one for, oh say $1000 or so. Or you can get used to doing the math in your head.

[bulldogchance]

I have a 1993 6.5 2500 changed gears and went taller on the tires took it to Dicks SpeedO and had it recalibrated $125.00.

[jifaire]

I have a 1993 6.5 2500 changed gears and went taller on the tires took it to Dicks SpeedO and had it recalibrated $125.00.

Dick's Speedo? You have a local business that calibrates speedometers?

Sheesh. I have enough trouble finding a place that changes oil. You think maybe I live in the boonies?

LOL ... like the guy said in the page I linked to, he'll do it for you for $50, or you can do it for yourself for $5 and change.

But I stand by the estimated $1000 to get the dealer to do it for ya... they charge $70 to hook up a tech-II and tell you "you have no codes", so getting them to actually DO something is gonna be pricey.

[kane67]

Well, I won't ask GM (price is :eek: )

Few weeks ago, I visited local service to read/test ABS module (had to change module later), engineer was using Tech tool II and when he was looking screen he just said "oh, you can set tire size also" and continued to ABS test.

Damn I was slow to say lets change it... have to try it next time.
Wasn't sure if it's possible, but like you say... it could be programmed.

Reason for that is to get TCC locked with D in real 80kmh (55mph) like originally. When pulling a heavy trailer/camper, the speed is ~87kmh before it locks. And there's ALWAYS someone driving exactly 80kmh or less in front of you.

Best Regards, kane67

[jifaire]

Well, I won't ask GM (price is :eek: )

Few weeks ago, I visited local service to read/test ABS module (had to change module later), engineer was using Tech tool II and when he was looking screen he just said "oh, you can set tire size also" and continued to ABS test.

?? It's worth giving him a phone call and asking him if it CAN be set using the tech-II, but my understanding is that you have to midify the DRAC


Reason for that is to get TCC locked with D in real 80kmh (55mph) like originally. When pulling a heavy trailer/camper, the speed is ~87kmh before it locks. And there's ALWAYS someone driving exactly 80kmh or less in front of you.

Hey, you have a 1994, so you can manually lock up your TCC with a toggle switch; that's what a lot of us OBD-I guys have done. I'll PM you a 'how-to' link, because the procedure is posted on another vendor's website.

Jim

[Chevylover]

?? It's worth giving him a phone call and asking him if it CAN be set using the tech-II, but my understanding is that you have to midify the DRAC



Hey, you have a 1994, so you can manually lock up your TCC with a toggle switch; that's what a lot of us OBD-I guys have done. I'll PM you a 'how-to' link, because the procedure is posted on another vendor's website.

Jim


Sounds very interesting to me too. Could you please send me another PM with the procedure too ?

That would be great !

Cu,
Sven