Speedometer Speed Incorrect

[single10]

I just purchased a 1992 LS400 with 98000 miles on it. Overall, I’m very

happy with the car. I’m slowly working out the few defects it has.

Using my GPS laptop, I’ve discovered the speedometer is off by 4 mph at

80 mph. That is, my speedometer reads 80 mph, but my actual speed is

84 mph. When the speedometer is 15 mph, the GPS reads 16 mph.

When the speedometer is 45 mph, the GPS reads 48 mph, and so on.

The problem is linear. The faster I go, the more it’s off.

The speedometer needle moves smoothly and all instrument cluster lights

work properly. I clocked between mile markers and the odometer is exact.

I put new Michelin MX4V+ 205/65R-15’s on, which are the correct size.

I have the same tires on my 90 LS400 (238,000 miles) and the speedometer

and my GPS are very close. The GPS clocks my actual speed as a hair slower

than the speedometer, which I can live with. At least it’s constant.

I have scoured Lexus board and cannot find this exact problem. If it were

the VSS, I would think there would be additional symptoms. I thought

maybe there was a speedometer gear at the end of the speedometer cable

that goes into the transmission, like (gulp) Fords, but I don’t know.

Is anyone familiar with this problem? Where is the VSS located exactly,

And what does it look like? Is there 1 speedometer gear somewhere?

I can use parts out of my 90 LS for troubleshooting, but don’t know where to

look!

Thank you all for your time. This is an awesome board. I’ve already

repaired my hood shocks the Mighty Max way, and more, thanks to this

Board. I still haven’t found an 8” 2 ohm subwoofer though, but that's for another thread.

[99lsguy]

single10,

There is a 1) VSS Connector and solenoid and.........

2) Direct clutch Speed sensor connector (on my 99LS)

They are along the drivers side of the transmission........

[single10]

I found a speedometer gear sensor in the driver side of the transmission. It's a black piece the shape of a tootsey roll and has a magnetic tip.

I swapped this sensor between my '90 and '92. No change. I also swapped the wheels between the 2 cars. No change. I don't see anything else that would have input to the speedometer.

The speedometer is accurate until I get to 50 Mph. Right after 50 mph, the speedometer is about 4 mph slower than true speed.

I'm going to swap the whole speedometer instrument cluster assembly next. Oh joy.

[Lexkeeper]

I found a speedometer gear sensor in the driver side of the transmission.  It's a black piece the shape of a tootsey roll and has a magnetic tip.

I swapped this sensor between my '90 and '92.  No change.  I also swapped the wheels between the 2 cars.  No change.  I don't see anything else that would have input to the speedometer. 

The speedometer is accurate until I get to 50 Mph.  Right after 50 mph, the speedometer is about 4 mph slower than true speed.

I'm going to swap the whole speedometer instrument cluster assembly next.  Oh joy.

←

Hello. I have a similar issue since I replaced the instrument cluster in my 1992 LS400 with the cluster from a 1991 LS400, except in this case, the speedometer and odometer read about 5% faster (and longer) than actual, i.e. reading is 84 mph when the actual speed is 80 mph. The wheel diameters are the same between the 1991 and 1992 LS400s. So, I am wondering if the differential gear ratio is different? Are the VSS sensors equivalent, or perhaps different VSS gear ratios to account for a different rear end gear ratio difference? Or some electronic calibration input is needed?

Sinlge10- what did you finally conclude on your speedometer discrepency, which is the reverse of mine?

Any help on this matter would be appreciated.

Cheers,

Lexkeeper

[svarog]

Maybe it could be not the speedometer that is showing wrong speed but the laptop with the GPS?

[dcfish]

I just purchased a 1992 LS400 with 98000 miles on it. Overall, I’m very

happy with the car.  I’m slowly working out the few defects it has.

Using my GPS laptop, I’ve discovered the speedometer is off by 4 mph at

80 mph.  That is, my speedometer reads 80 mph, but my actual speed is

84 mph.  When the speedometer is 15 mph, the GPS reads 16 mph. 

When the speedometer is 45 mph, the GPS reads 48 mph, and so on. 

The problem is linear.  The faster I go, the more it’s off.

The speedometer needle moves smoothly and all instrument cluster lights

work properly.  I clocked between mile markers and the odometer is exact.

I put new Michelin MX4V+ 205/65R-15’s on, which are the correct size.

I have the same tires on my 90 LS400 (238,000 miles) and the speedometer

and my GPS are very close.  The GPS clocks my actual speed as a hair slower

than the speedometer, which I can live with.  At least it’s constant.

I have scoured Lexus board and cannot find this exact problem.  If it were

the VSS,  I would think there would be additional symptoms.  I thought

maybe there was a speedometer gear at the end of the speedometer cable

that goes into the transmission, like (gulp) Fords, but I don’t know.

Is anyone familiar with this problem?  Where is the VSS located exactly,

And what does it look like?  Is there 1 speedometer gear somewhere? 

I can use parts out of my 90 LS for troubleshooting, but don’t know where to

look! 

Thank you all for your time.  This is an awesome board.  I’ve already

repaired my hood shocks the Mighty Max way, and more, thanks to this

Board.  I still haven’t found an 8” 2 ohm subwoofer though, but that's for another thread.

←

single10, Are you looking for a stock sub replacement? Didn't mean to hijack the thread.