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Speedometer calibration

Welcome to the forum @Up2theaxles Look behind the glove box above the PCM for a small white box with a connector on it. it's called a VSSB or DRAC. there are writeups on how to mod this thing so you can adjust your speedo.
 
I’ll have to see if mine has the dip switches but I found a place to get one that has switches if mine doesn’t. Now I just gotta research how to set the switches for different gear ratios and tire sizes.
 
Well I feel kinda stupid. My truck does not have a vssb. It goes straight to the pcm. So I guess a programmer is my only option. I think a couple people tried to tell me that but I just didn’t understand. Thank you for all your help though. It’s appreciated. Now I know. Lol
 
@Glagulator I would be curious if a VSSB could be added and calibrated using the output speed signal wire then go into the ECM on the 96+ units for those that don't have access to having their ECM reprogrammed. It would seem as a simple fix on the cheap side if it would work!
 
I don't think that will work.
The VSSB does not output a modified VSS signal (40 PPR), that goes straight thru.
It only outputs modified PPM signals.
The gasser PCM would need a modified VSS signal.
There are magic boxes that will do that.
 
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