I was wondering, if through PROM burning, I could calibrate the speedometer to compensate for different tire sizes/rear end gears. It is an electric speedometer, not cable driven. Thanks.

 

Nope

------------------
, Jon (350 TBI!)
91 Red My website

 

To elaborate on JPrevost's answer; there are no "drivers" from the ECM to the speedo. You CAN correct the Pulses/Mile constant within the eprom but it only affects the display on your scan tool, not the speedo itself.

The Pulses/Mile Constant is more of a "correction" factor to ensure your scan tool gets the correct reading. I found my scan tool displayed the vehicle speed slightly higher than my speedo. My speedo with 255/16s was exactly correct and my scan tool displayed the MPH a couple MPH higher. I found changeing the constant from 4007 P/M to 4,024 P/M made the scan tool record the exact same MPH as my speedo...but had no affect on the speedo itself.

 

Depending on what your working on, you might have a DRAC module. Hunting thru the GMECM archives will give you all the info there is about them.

 

Actually .... you can if you have the 730 F-Body. Dave Zug recently did this with his '91 Z28 Convertible that he added a 6 speed to. I should have mentioned this to the board when Dave first told me about it but I forgot Anyhow ...

http://www.delanet.com/~tgp/92Z28/02-730-vss4T56.html

Happy reading and Great job to Dave Zug!!!!!!

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

OK, so how do I change this in GMEpro with a 6E code? Is it even possable?


------------------
'86 TA, T-tops, T-5, 3.73, 4 wheel disks 350, compucam 2040, performer intake,SLP Headers, 3" race magnum muffler, 1.6 Comp rockers, Ripper shifter, perf. friction pads, Hypertech ignition, Earls brake hoses, Hotchkis springs, Tokico Illumina 5 adjustable shocks and struts, Lakewood panhard and trailing arms
14.50@ 97 with carb... now converted to TPI

 

I was searching the boards for my name and wanted to update the link Tim S posted...

http://www.eecis.udel.edu/~dzug/92z2...0-vss4T56.html

Enjoy...

~Dave