Speedomter/Odometer Discrepancy
10-20-09, 01:10 PM
#17
Lexus Test Driver
The Mike is right!!!!
Someone asked me to pass along any info I gathered on this, so here goes:
To recap, I have confirmed through GPS tracking, police radar and side-by-side tracking with another vehicle that my speedometer reads 3mph higher than my actual speed. IOW, when my speedometer shows 30mph, I'm actually going only 27; when it shows 60mph, I'm actually doing only 57, etc.
It occurred to me that my odometer must also be reading too high, meaning it is racking up too many miles. That's a factor not only for warranty purposes, but also because I have a lease with 15,000 miles per year and if I exceed that I have to pay Lexus 20¢ per mile. At 45,000 miles, that will amount to about 2,250 extra miles, or about $450.
I wrote Lexus a nice letter outlining this and asking that they cut me some slack if I exceeded my mileage limitation. They called me and told me the speedo and odo use entirely separate inputs, so the fact the speedo was off didn't mean the odo is. (They couldn't comment when I asked if that therefore meant they could BOTH be wrong.
)
So today I sat down with my dealer's Shop Manager and we studied wiring diagrams and system flow charts for an hour. What we concluded is that:
1. In addition to wheel sensors, the speedo does indeed use some additional info sources, like wheel spin sensors, that the odo ignores. (After all, if the wheels are spinning the speedo needle shows it, while the odo doesn't, since the car isn't really moving.)
2. The odo relies primarily on the wheel sensors to record forward movement, as expected.
The interesting point, though, is this: The signals from both the speedometer pickups and the odometer pickups are run through something called a "Certification ECU", a computerized control unit that appears to compare and confirm (certify) the values. After taking into account the signals that don't apply to the odo, the values must essentially match or the system will register an error code.
What that says to me is that if the speedo is off, the odo is off.
It is well-known that Acura lost a class action suit for this very thing a couple years ago, and they ended up extending warranties and mileage on leases. I'm not trying to stir up a lawsuit, but I have again written Lexus asking that they consider this discrepancy if my mileage exceeds 45,000 at lease end.
Take it for what it's worth.
.
.
To recap, I have confirmed through GPS tracking, police radar and side-by-side tracking with another vehicle that my speedometer reads 3mph higher than my actual speed. IOW, when my speedometer shows 30mph, I'm actually going only 27; when it shows 60mph, I'm actually doing only 57, etc.
It occurred to me that my odometer must also be reading too high, meaning it is racking up too many miles. That's a factor not only for warranty purposes, but also because I have a lease with 15,000 miles per year and if I exceed that I have to pay Lexus 20¢ per mile. At 45,000 miles, that will amount to about 2,250 extra miles, or about $450.
I wrote Lexus a nice letter outlining this and asking that they cut me some slack if I exceeded my mileage limitation. They called me and told me the speedo and odo use entirely separate inputs, so the fact the speedo was off didn't mean the odo is. (They couldn't comment when I asked if that therefore meant they could BOTH be wrong.
)So today I sat down with my dealer's Shop Manager and we studied wiring diagrams and system flow charts for an hour. What we concluded is that:
1. In addition to wheel sensors, the speedo does indeed use some additional info sources, like wheel spin sensors, that the odo ignores. (After all, if the wheels are spinning the speedo needle shows it, while the odo doesn't, since the car isn't really moving.)
2. The odo relies primarily on the wheel sensors to record forward movement, as expected.
The interesting point, though, is this: The signals from both the speedometer pickups and the odometer pickups are run through something called a "Certification ECU", a computerized control unit that appears to compare and confirm (certify) the values. After taking into account the signals that don't apply to the odo, the values must essentially match or the system will register an error code.
What that says to me is that if the speedo is off, the odo is off.
It is well-known that Acura lost a class action suit for this very thing a couple years ago, and they ended up extending warranties and mileage on leases. I'm not trying to stir up a lawsuit, but I have again written Lexus asking that they consider this discrepancy if my mileage exceeds 45,000 at lease end.
Take it for what it's worth.
.
.
I see folks on this site and other upscale item sites say all the time"if you have a problem paying it you cant afford it,stop complaining"! I disagree with that frame of mind. I say you paid for a car to go 60 mph when driven, not 57 mph when driven. You pay the total lease amount each month, not partial payment. Anyone taken the dealers side needs to see it from Mike's eyes. I support YOU fellow member. Dont let anyone take from YOU what YOU worked hard for! It IS WORTH IT! All the best MIKE!!! L.G.N.M
Last edited by usermel; 10-20-09 at 01:14 PM. Reason: alot!!
10-25-09, 09:40 AM
#18
Driver School Candidate
Shortly after I purchased my LS I too noticed the speedo was off about 3 mph at 70 mph. I knew by changing the tire size I could possible fix the problem. So when it was time to change tires I went from the oem 235/50x18 to a taller 225/55x18 tire. That changed the overall diam. from 27.3" to 27.8" and reducing the revs per mile from 763 to 750. The tire fits fine Its a bit taller and a bit narrower but works superbly. The result in speedo error is now a liveable 1 mph and barely that.
When Mike started mentining the odometer thing I got out my gps again and took a little ride. With the new tires The gps shows the car travels 1.02 miles for every 1.00 miles on the odo. Thats 2 hundreds of a mile (or about 105 ft ) further.
After my first 20 miles on the cars odo. The gps showed we had actually traveled 20.4 miles .
I realize the new tires should have some effect on this but It appears that the odo is pretty close.
In the next 50,000 miles on the odo. I will have traveled an extra 1000. miles NOT showing for any added lease charges.
Mike I'm in Dallas very often and I would offer my gps to compare the distances on your tire size.
Cheers, RT
When Mike started mentining the odometer thing I got out my gps again and took a little ride. With the new tires The gps shows the car travels 1.02 miles for every 1.00 miles on the odo. Thats 2 hundreds of a mile (or about 105 ft ) further.
After my first 20 miles on the cars odo. The gps showed we had actually traveled 20.4 miles .
I realize the new tires should have some effect on this but It appears that the odo is pretty close.
In the next 50,000 miles on the odo. I will have traveled an extra 1000. miles NOT showing for any added lease charges.
Mike I'm in Dallas very often and I would offer my gps to compare the distances on your tire size.
Cheers, RT
10-26-09, 08:56 AM
#19
Lexus Test Driver
Thread Starter
Shortly after I purchased my LS I too noticed the speedo was off about 3 mph at 70 mph. I knew by changing the tire size I could possible fix the problem. So when it was time to change tires I went from the oem 235/50x18 to a taller 225/55x18 tire. That changed the overall diam. from 27.3" to 27.8" and reducing the revs per mile from 763 to 750. The tire fits fine Its a bit taller and a bit narrower but works superbly. The result in speedo error is now a liveable 1 mph and barely that.
When Mike started mentining the odometer thing I got out my gps again and took a little ride. With the new tires The gps shows the car travels 1.02 miles for every 1.00 miles on the odo. Thats 2 hundreds of a mile (or about 105 ft ) further.
After my first 20 miles on the cars odo. The gps showed we had actually traveled 20.4 miles .
I realize the new tires should have some effect on this but It appears that the odo is pretty close.
In the next 50,000 miles on the odo. I will have traveled an extra 1000. miles NOT showing for any added lease charges.
Mike I'm in Dallas very often and I would offer my gps to compare the distances on your tire size.
Cheers, RT
When Mike started mentining the odometer thing I got out my gps again and took a little ride. With the new tires The gps shows the car travels 1.02 miles for every 1.00 miles on the odo. Thats 2 hundreds of a mile (or about 105 ft ) further.
After my first 20 miles on the cars odo. The gps showed we had actually traveled 20.4 miles .
I realize the new tires should have some effect on this but It appears that the odo is pretty close.
In the next 50,000 miles on the odo. I will have traveled an extra 1000. miles NOT showing for any added lease charges.
Mike I'm in Dallas very often and I would offer my gps to compare the distances on your tire size.
Cheers, RT
I might add that - since I realized this is not a "percentage" error, but a flat 3mph error - the amount the mileage is off at the end of my lease will vary according to my overall average speed. This means if I average 30mph over a long period of time (which you can do in the city, with frequent stops, etc.), the error is actually 10%.
That would mean when my odo shows 45,000 miles it might have gone only 40,500 and "cheated" me out of 4,500 miles. At 20 cents a mile, that's $900.00 I'd owe them!
.
.
12-15-09, 02:08 PM
#20
Lexus Test Driver
Thread Starter
A follow-up to my speedo error post
I couldn't find my old thread about the speedometer/odometer error to update it, but I said I'd let you know the outcome. I just got a call from Lexus about it.
They maintain that the error is "within specifications", and that there is no repair available to correct the speedo-odo reading.
But they did tell me that my letters are on record, and that they will accommodate me in some way if my mileage is in excess of 45,000 at the end of my lease. They couldn't be specific - and I understand that - since we're talking about what might or might not be an issue, a year from now. But they did say they would compensate me in some fashion, to be determined at the time.
That's what I wanted, and I'm happy with that. It gives me some room for negotiation, and I figure they will be fair. Of course, my preference would be to get the speedo fixed, but that doesn't seem to be in the cards.
Overall, I'm satisfied.
.
.
They maintain that the error is "within specifications", and that there is no repair available to correct the speedo-odo reading.
But they did tell me that my letters are on record, and that they will accommodate me in some way if my mileage is in excess of 45,000 at the end of my lease. They couldn't be specific - and I understand that - since we're talking about what might or might not be an issue, a year from now. But they did say they would compensate me in some fashion, to be determined at the time.
That's what I wanted, and I'm happy with that. It gives me some room for negotiation, and I figure they will be fair. Of course, my preference would be to get the speedo fixed, but that doesn't seem to be in the cards.
Overall, I'm satisfied.
.
.
09-16-10, 12:32 PM
#23
Driver School Candidate
Join Date: Sep 2009
Location: IL
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
Hello Mike,
I came across your thread when I noticed that my Lexus LS460 was registering about 2-3 more miles than the streetside radar displays here in Dallas and googled odometer accuracy. I appreciate your persistence on the subject. Right on!
Don Michel (Illinois resident visiting in Dallas for a few days)
I came across your thread when I noticed that my Lexus LS460 was registering about 2-3 more miles than the streetside radar displays here in Dallas and googled odometer accuracy. I appreciate your persistence on the subject. Right on!
Don Michel (Illinois resident visiting in Dallas for a few days)
Thread
Thread Starter
Forum
Replies
Last Post
