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Discussion Starter · #1 ·
We have a 2004 Santa Fe with approx. 71000 miles on it (it's a mom-mobile), and for the last 3 years, we've had issues with the speedometer dropping down to 0 while driving. It's been to the dealership 8 times (we got the extended warranty at purchase). They replaced the speed sensors twice, and the speedometer multiple times, and this was obviously not the solution. They were able to repair it for 2 years, after tightening up some connections, and then we were back in the shop. My warranty is up in less than 2 months, and I have no faith that the most recent repair (replacing the etac for the 3rd time - the first 2 were for a different electrical issue in 2007) will solve the problem. We are getting nowhere with the regional manager or HIS supervisor. All we really want is a warranty for THIS repair. Theoretically, I SHOULD be able to drive this car for another 50K miles, but I don't believe that the speedometer is going to hold out.

Basically, what I want to know is if they are missing something in the repair, and if we are just SOL on getting Hyundai to do anything for us.
 

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The speedometer system isn't that complicated.
The vehicle speed sensor (VSS) is mechanically hooked into the gearbox gears and is giving speed pulses. These pulses go to the instrument cluster and are counted by the intruments chip and this chip sends a voltage to the speedometer.
So, failing, they replaced the sensors. But there is only one, the VSS.
Sometimes peaple talk about input and output sensors on the gearbox but they are for sensing shaft speeds by the ECU, nothing to do with vehicle speed sensing. So when they replaced the sensors I hope they did not change those instead of the VSS. Furthermore it is a mechanical hookup.
So it could be the internal coupling gear within the gearbox has worn out so the (even new) sensor might loose contact there. Was that ever checked or replaced?
Was the entire instrument cluster replaced (including it's control chip) or only the speedometer instrument?
ETACS chip is for controlling immobilisation, door locks, switches etc. and has nothing to do with instrument cluster functions like speed measurements.
So, all in all, I wonder what they replaced these 8 times to really solve the issue?
First of all I would look for that gearbox hookup of the VSS because that's a mechanical issue, prone to wearing out.
Good luck,
Paul
 

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Which engine,, and ABS or no ABS ??

Speed system is goofy on Santa Fe.. Uses speed sensor at final drive, and speed off RF wheel, which come into HECO as A/C wave, and converted to D/C wave and sent on down the line.

Other possibility is the driven gear at final drive (for speed sensor) poor condition.. had 1 that got trans because drive gear on differential took dump, would not drive the driven gear.
 

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Is it an intermittent issue ( drops to zero while driving and then comes back ) or does it work and then quit working altogether until you let the car cool off, or just simply turn the key off.

As stated already, the speedo is going to be based off the VSS, which sends a signal to the computer which sends the signal to the instrument panel. If it's something that seems to happen after driving for a while, it could be something heat related.

In any case, they are not doing a proper diagnosis IMHO, they are simply blaming the usual suspects and figuring that it's good. There's a possibility that you have a difficult to diagnose problem ( which intermittent problems usually are ). They need to put a diagnostician on it, not just a "mechanic"...you need someone that knows how to diagnose the problem the right way, the first time.

It might be worth your while to look for an automotive school that specializes in diagnostics and ask them if they'd be interested in doing it. They'll charge a fee, but it will be likely the cost of parts and the diagnostic fee.

I subscribe to you tube channel by a guy that goes by the name ScannerDanner, and I've contacted him personally...super approachable. He's not going to diagnose your problem, but he could probably tell you where to go and what you might encounter for expense. He told me he charges 75/hr and normally needs no more than an hour to diagnose most problems. He uses a laptop and a lab scope. If I were looking to change professions, he'd have inspired me to become a true diagnostician.
 

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Discussion Starter · #5 ·
It's an intermittent issue, usually when I'm going over bumpy roads (which are everywhere in Oklahoma), and over 40mph. I picked it up yesterday, after the service manager gave me a written warranty on the repair for 1 year or 12000 miles. Within 20 miles of driving yesterday, my check engine light came on. I just can't win.
 

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But with a CEL, you can read an error code. You did not mention in your first post the CEL would come up. So could this be an other issue?
And which sensors did they replace? And did they look at the driven wheel, like also SBR mentioned?

Paul
 
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