# My First Problem



## sciphi (Aug 26, 2011)

It'll definitely do 109+ mph given enough room.

Hope it doesn't repeat itself. Sounds like a cluster error, or a vehicle speed sensor on the fritz. I'd bet cluster, knowing others have had problems with theirs.


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## Xlr8machineshop (Jul 17, 2011)

It's a known problem happend to a number of people on this site including me brought it to the dealer and they could not recreate so they did nothing apparently you have to complain a few times for a fix


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## Jim Frye (Mar 16, 2011)

Skagit ECO said:


> While stopped at a red, light my digital speedometer read 109 mph!! By the time the light turned green it had dropped to 99. Once I got going the speedometer displayed actual speed. I have only noticed this once. Otherwise no problems after 4,500 miles. BTW my '12 ECO MT DIC reports an average of 35.0 mpg since new. Fuelly reports about 4% less at 33.5 mpg. About 50% interstate driving all on 87 octane +10% ethanol. Overall it's a great car for the money although I doubt it will do 109.


There was a TSB out last year that addressed dirty wheel speed sensors and how to correct it. The wheel speed sensors are rings with magnet material embedded in them. If the rings get dirt on them, they can give false speed readings to the computers.


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## XtremeRevolution (Jan 19, 2012)

Jim Frye said:


> There was a TSB out last year that addressed dirty wheel speed sensors and how to correct it. The wheel speed sensors are rings with magnet material embedded in them. If the rings get dirt on them, they can give false speed readings to the computers.


Odd...It was always transmission sensor that determined wheel speed, as the wheel speed sensors have always been used for ABS and occasionally tire pressure purposes. You sure the car goes based on wheel speed sensors to determine its actual speed?

Those sensors are also magnetic and detect rotations based on pulses when a gear-type plate moves across them. It takes quit a bit of dirt to disrupt that magnetic field.

BTW, you can probably get a bit better fuel economy if you're careful. I averaged 37mpg last tank. I live in the suburbs, but that was still 90% in-town driving.


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## 20126spdRS (Dec 27, 2011)

my dealer did a BCM software update to get this fixed it was happening to me about 3-4 times a week. dealer could not get it to happen. is the car an M/T??? my car has done it twice since then and i got the update 2-3 months ago. if you notice the radio gets louder also due to the speed adjusted sound I.E. the radio gets louder as you go faster to compinsate for road noise and wind ext...


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## Jim Frye (Mar 16, 2011)

XtremeRevolution said:


> Odd...It was always transmission sensor that determined wheel speed, as the wheel speed sensors have always been used for ABS and occasionally tire pressure purposes. You sure the car goes based on wheel speed sensors to determine its actual speed?
> 
> Those sensors are also magnetic and detect rotations based on pulses when a gear-type plate moves across them. It takes quit a bit of dirt to disrupt that magnetic field.
> 
> BTW, you can probably get a bit better fuel economy if you're careful. I averaged 37mpg last tank. I live in the suburbs, but that was still 90% in-town driving.


It was my impression that the wheel rotation sensors could affect the speed sensing in the computer. I'd like to be proven wrong. The rings on the wheel speed sensors on the Cruze are segmented magnetics and there are no "gear tooth" to give the pulses. If they get dirty, the pulses get weak and are not picked up correctly, thus giving the wrong readings.


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## H3LLON3ARTH (Dec 16, 2011)

Jims right how could the tranny tell you how fast both wheels spin simotanisly 

Sent from my R800x using AutoGuide.com App


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## sciphi (Aug 26, 2011)

H3LLON3ARTH said:


> Jims right how could the tranny tell you how fast both wheels spin simotanisly
> 
> Sent from my R800x using AutoGuide.com App


On every other car I've worked on the speedometer has been fed off of a transmission-mounted vehicle speed sensor. Once I had to replace a speedometer cable that went right to the transmission. That was a barrel of fun, not! 

The Cruze may be different. It may well use the wheel speed sensors to feed the speedometer, and eliminate a sensor/failure point on the transmission.


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## Jim Frye (Mar 16, 2011)

sciphi said:


> On every other car I've worked on the speedometer has been fed off of a transmission-mounted vehicle speed sensor. Once I had to replace a speedometer cable that went right to the transmission. That was a barrel of fun, not!
> 
> The Cruze may be different. It may well use the wheel speed sensors to feed the speedometer, and eliminate a sensor/failure point on the transmission.


Back in the day of rear wheel drive, the mechanical speedo drive was taken from a gear set on the output shaft at the tail end of the transmission. The cable ran up to the dash. You could change gear sets to compensate for different sized tires (i.e. Street Slicks). The speedometer on my '65 Corvair Corsa was driven from the spindle of the left front wheel, as the transaxle was back behind the rear seats. Worked fine, except for speeds over 120 mph. Then the cable would overheat in a tight bend and snap.


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## 70AARCUDA (Nov 14, 2010)

sciphi said:


> The Cruze *may be *different. It may well use the wheel speed sensors to feed the speedometer, and eliminate a sensor/failure point on the transmission.


...the Cruze (and most new FWD cars) *are* different. Almost ALL cars with ABS use speed sensors _*on each wheel*_ so the ABS system can detect if _any_ wheel is locking or spinning.


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## H3LLON3ARTH (Dec 16, 2011)

Yes thats true I deal with tthis everyday at the shop we use snap on and matco readers almost everyday do to mud dirt even rocks

Sent from my R800x using AutoGuide.com App


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## Jim Frye (Mar 16, 2011)

70AARCUDA said:


> ...the Cruze (and most new FWD cars) *are* different. Almost ALL cars with ABS use speed sensors _*on each wheel*_ so the ABS system can detect if any wheel is locking or spinning.


Correct me if I am wrong, but that is how stability control gets its input also. Differential input from the individual wheels.


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## 70AARCUDA (Nov 14, 2010)

Jim Frye said:


> Correct me if I am wrong, but that is how stability control gets its input also. Differential input from the individual wheels.


...you are correct.


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