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Speedo / odo
- Thread starter jeedee
- Start date
- Joined
- Jun 2, 2012
- Messages
- 25,363
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- 8,369
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- Location
- canada
- Vehicle Year
- 1994
- Make / Model
- Ford
- Transmission
- Manual
Yes, they share the same signal.
In 2002 the computer calibrates the drive shaft RPMs using factory rear axle ratio and factory tire size, and sends out the corrected 8,000PPM(pulse per mile) on 1 wire to the dash, speedo and odo share that signal
If you change tire size or rear axle ratio then that signal would be off, Computer can be recalibrated
Or you can install an interface between OSS(output shaft speed) sensor and computer to correct signal for changes you made
Example of interface here: http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=126/category_id=287/mode=prod/prd126.htm
There are other brands, this is just an example
All Fords use 8,000PPM signals at speedometer
In 2002 the computer calibrates the drive shaft RPMs using factory rear axle ratio and factory tire size, and sends out the corrected 8,000PPM(pulse per mile) on 1 wire to the dash, speedo and odo share that signal
If you change tire size or rear axle ratio then that signal would be off, Computer can be recalibrated
Or you can install an interface between OSS(output shaft speed) sensor and computer to correct signal for changes you made
Example of interface here: http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=126/category_id=287/mode=prod/prd126.htm
There are other brands, this is just an example
All Fords use 8,000PPM signals at speedometer
jeedee
Member
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- Oct 9, 2012
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- Automatic
Hey Ron....thanx for the info. Had new tires put on...factory size...and now my speedo is reading about 4 MPH over actual speed. Am not sure if the tires caused this or was that way b/f I installed them. The truck was stored for about 5 years, and don't remember ever checking the speedo. Can't seem to locate the speed sensor on the trans....many wires / connections. Web images seem to contradict each other....top of tranny....differential....side of tranny....etc.......?
Again....thanx for the info.....Charlie.
Again....thanx for the info.....Charlie.
- Joined
- Aug 19, 2001
- Messages
- 10,755
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- 583
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- Location
- So. Calif (SFV)
- Vehicle Year
- 1990
- Make / Model
- Bronco II
- Engine Type
- 2.9 V6
- Engine Size
- 2.9L V6
- Transmission
- Manual
- 2WD / 4WD
- 4WD
- Tire Size
- 35x12.50R15
2002 has the sensor on the rear axle (and is shared with the ABS). Pre-'98 trucks had the sensor on the trans (or t-case if 4x4).
If the speedo reads smoothly (it's only off just a little bit) and there's no ABS light on or anything, it's unlikely to be the sensor. It probably just needs recalibrated (or you could go up one tire size and it'll probably be pretty close then... It's also possible a PO had put such tires on it at some point and recalibrated it for those tires).
If the speedo reads smoothly (it's only off just a little bit) and there's no ABS light on or anything, it's unlikely to be the sensor. It probably just needs recalibrated (or you could go up one tire size and it'll probably be pretty close then... It's also possible a PO had put such tires on it at some point and recalibrated it for those tires).
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1994 FORD RANGER 2.3 OBD1 TEST INTERFACE QUESTION
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