speedo problem

JAYPOUW · Jul 9, 2010

this is driving me crazy ok this is what i have .
95 gts have working speedo but not reading correctly ,reads 150 in 5th gear running 2 grand on tach.

have tried different speedo,different tranny wiring harness, new vss,still no luck
radio and everything else work except trip counter under mileage. any help would be great as this is driving me nuts . thanks

Chythar · Jul 9, 2010

This is a classic issue when the rear gears have been changed. Have you changed the gears in the differential? Or did you buy the car modified? With the high difference in the speed, I'm guessing your car came with the 2.73 gear set and you now have 4.10's.

JAYPOUW · Jul 9, 2010

no gear change

ok lets try this this is the donor body the gts was crashed beyond repair so i have a donor body that i transferred all the parts onto the speedo was fine with the donor no problems what so ever then engine ,trans and so forth were swapped now speedo is off only thing that is still v6 is rear end and that if fine because it worked with the 6 .had the same problem with the crashed body it has a vss not a drive gear .

toyman · Jul 9, 2010

JAYPOUW said:
ok lets try this this is the donor body the gts was crashed beyond repair so i have a donor body that i transferred all the parts onto the speedo was fine with the donor no problems what so ever then engine ,trans and so forth were swapped now speedo is off only thing that is still v6 is rear end and that if fine because it worked with the 6 .had the same problem with the crashed body it has a vss not a drive gear .

The point Chythar was making was the differential gears may be different than what you had in the GTS. And there is a drive and driven gear even with the VSS, The drive gear is integral to the transmission (output shaft) and the driven gear is what signals the VSS. So since you have the V6 differential and it sound like you don't know the gear ratio now or what was in the GTS here's what you need to do. Jack up the rear end and rotate a wheel one revolution while you count the number of revolutions on the drive shaft. If for example, one turn on the wheel = 2 3/4 turns on the drive shaft the rear gear is 2.73:1. Once that is determined you need to pull the driven gear and count the number of teeth and note the gear color. From there someone should be able to tell you what driven gear you will need to correct the speedometer.

Chythar · Jul 10, 2010

toyman said:
The point Chythar was making was the differential gears may be different than what you had in the GTS. And there is a drive and driven gear even with the VSS, The drive gear is integral to the transmission (output shaft) and the driven gear is what signals the VSS. So since you have the V6 differential and it sound like you don't know the gear ratio now or what was in the GTS here's what you need to do. Jack up the rear end and rotate a wheel one revolution while you count the number of revolutions on the drive shaft. If for example, one turn on the wheel = 2 3/4 turns on the drive shaft the rear gear is 2.73:1. Once that is determined you need to pull the driven gear and count the number of teeth and note the gear color. From there someone should be able to tell you what driven gear you will need to correct the speedometer.

Thank you Richard, you said it much better.

JAYPOUW · Jul 10, 2010

Neither rear end makes a difference because the the speedo doesn't work correctly because the v6 is a stock reared where the gts has 4:10 I know this only thing left would be the tranny will swap it out this weekend . I thought it was the PCM because it has a a9L in it but swapped the harness back to stock and PCM and still didn't work

JAYPOUW · Jul 10, 2010

Doesn't have a gear on vss only magnet

JAYPOUW · Jul 10, 2010

Ok I was wrong on the speedo reading it is reading 100 mph in second gear turning 1500 rpm

toyman · Jul 10, 2010

JAYPOUW said:
Doesn't have a gear on vss only magnet

There is a gear. Disconnect the VSS connector at the transmission. Undo the hold down bolt and pull the VSS sensor. The gear should come out with the sensor. Believe me it's there.

JAYPOUW · Jul 11, 2010

Not on mine that that was the problem first ordered one from ford and went to put in in an valaaa nope not the same only a magent

toyman · Jul 11, 2010

JAYPOUW said:
Not on mine that that was the problem first ordered one from ford and went to put in in an valaaa nope not the same only a magent

Okay. What transmission is in there?

JAYPOUW · Jul 12, 2010

Ok after Putting on the and not laying on my back looks to be a newer t45

toyman · Jul 12, 2010

JAYPOUW said:
Ok after Putting on the and not laying on my back looks to be a newer t45

Makes no sense. The T-45 has either a 7 (F6ZZ-AA) or 8 (F6ZZ-BA) tooth drive gear. The VSS is a small permanent magnet generator that is driven by a gear inside the transmission. (It's this gear that will affect the speedometer reading. This gear will have from 17 to 21 teeth and is color coded). The VSS outputs a voltage that varies according to the vehicle road speed.

JAYPOUW · Jul 12, 2010

Yeah what I said makes no sense to me either my t5 has the vss with the gear and it's blue but this one doesn't even tried to see it it was broken off in side but it not

toyman · Jul 12, 2010

JAYPOUW said:
Yeah what I said makes no sense to me either my t5 has the vss with the gear and it's blue but this one doesn't even tried to see it it was broken off in side but it not

Then it's just missing although I can't see where there would be any signal. Pop one in and go from there. If it doesn't go in, then there is a broken piece inside.

The blue one is strange for the T5. That was a 16 tooth gear for the AODE.

JAYPOUW · Jul 14, 2010

going to check it later today once its back in the air plus i'll take a picture of what i pull out compared to what is supposed to be in there.

dirtbikedoc · Jul 21, 2010

Have you figured it out yet? I have the exact same problem on a 94 GT that I just got on a trade.

JAYPOUW · Aug 3, 2010

here is the difference in trannys

one is a borg and warner and the other is a tremic

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