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Speedometer Off

  • Thread starter Thread starter tjmaxx
  • Start date Start date Jul 15, 2012

tjmaxx

Member
Jun 21, 2004
157
3
19
Jul 15, 2012
#1
  • Jul 15, 2012
  • #1
I have a 4.10 gear in my 96 gt, I have a speed calibrator to fix the speedometer being off but my question is can I just purchase a tuner and fix the speedometer? I think the answer is no?
 

trinity_gt

10 Year Member
Jan 31, 2003
3,125
81
99
Canada
Jul 15, 2012
#2
  • Jul 15, 2012
  • #2
tjmaxx said:
I have a 4.10 gear in my 96 gt, I have a speed calibrator to fix the speedometer being off but my question is can I just purchase a tuner and fix the speedometer? I think the answer is no?
Click to expand...

You are correct.
 

tjmaxx

Member
Jun 21, 2004
157
3
19
Jul 15, 2012
#3
  • Jul 15, 2012
  • #3
That sucks lol
 

Rusty67

20+ Year Stangneter
Dec 3, 2002
3,749
37
109
LA, CA
Jul 19, 2012
#4
  • Jul 19, 2012
  • #4
If you remove the speed cal and use a tuner you should be able to set the gear ratio in the tune. You just need a tuner capable of changing the gear ratio.

If your speedo's calibration is off a tuner can't fix that but if it is just a gear ratio issue then you should be fine.
 
M

m0squ1t0

Member
Feb 3, 2011
103
2
19
Jul 22, 2012
#5
  • Jul 22, 2012
  • #5
what about from a gauge swap (160mph svt cluster in gt) how to calibrate for that
 
D

Deleted member 38176

Jul 22, 2012
#6
  • Jul 22, 2012
  • #6
tjmaxx said:
That sucks lol
Click to expand...

Remove whatever "speed calibrator" you have and a tuner will correct it.
 

wmburns

SN Certified Technician
Aug 14, 2009
5,892
514
204
Houston Texas
Jul 22, 2012
#7
  • Jul 22, 2012
  • #7
I can see from the wiring diagrams that for the 98 and older Mustangs, the VSS sensor output goes to BOTH the PCM and the cluster.

For the 99+ MY, the OSS sensor output goes to the PCM only. The PCM sends a speed command to the cluster.

To me, that implies for the 98 and older Mustangs that a tuner can not be used to correct for axle changes. Because the tuner would correct the PCM speed but the cluster would still display the wrong speed.

The turner works for the 99+ because once the PCM has the correct speed, the cluster has to be correct.

Regarding the question about the cluster swap, the answer is different depending upon the MY.
 

Rusty67

20+ Year Stangneter
Dec 3, 2002
3,749
37
109
LA, CA
Jul 22, 2012
#8
  • Jul 22, 2012
  • #8
I didn't realize the earlier SN95 fed the dash directly from the VSS, looks like trinity was right on with that and wmburns strikes again with the mad knowledge.

What year cluster are you going to swap in ?
 
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