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Discussion Starter · #1 · (Edited)
2005 Hyundai Tucson 2.0L 4cyl automatic transmission. Okay so my wife is driving home from work and her speedometer suddenly went from 65mph-0 then back up to 65mph. The next day I took it for a drive and the speedometer wasn’t working for the first few minutes then suddenly it started working again. I assume it’s either a loose connection or failing sensor. When I looked it up it says it has 2 sensors. An input and an output sensor. I have no idea where they are located. I think I found 1 next to the spark plugs but not sure if that is the input or output. Any help would be greatly appreciated. Thank you.
note that I just replaced a leaking VVT solenoid the day before this started. I don’t believe that has anything to do with the speedometer but if it does let me know. Thank you.
 

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2005 Hyundai Tucson 2.0L 4cyl automatic transmission. Okay so my wife is driving home from work and her speedometer suddenly went from 65mph-0 then back up to 65mph. The next day I took it for a drive and the speedometer wasn’t working for the first few minutes then suddenly it started working again. I assume it’s either a loose connection or failing sensor. When I looked it up it says it has 2 sensors. An input and an output sensor. I have no idea where they are located. I think I found 1 next to the spark plugs but not sure if that is the input or output. Any help would be greatly appreciated. Thank you.
note that I just replaced a leaking VVT solenoid the day before this started. I don’t believe that has anything to do with the speedometer but if it does let me know. Thank you.
PG-A & PG-B is shaft speed sensors. They used to verify slippage based on mapped gear ratio and engine speed

Speedometer should be function of VSS on transmission in the differential adjacent to right hand side of differential case.

May have to remove air inlet stuff to see down in, but there be a 3 wire connector on top of speed sensor that would fit same place a speedometer cable drive would in old days.. Unplug connector, remove the bolt, and lift that thing out of case,, look at driven gear, they get ate up over time and drive gear wont rotate it

Seen the VSS body itself also burn up inside / see smoke and smell of electric fire.. search speedomter gear here and in the EF Sonata pages, about sure there be pics of parts here somewhere

They wont be on shelf at dealer level, they have to be order from Part Distribution Center to dealer
 

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Discussion Starter · #3 ·
Thank you for your reply. I see the VSS you’re mentioning under the air box. When I look for the parts however it mentions 2. A VSS input sensor and a VSS output sensor. I’ve tried looking at diagrams online and only see the location of the one under the air box. Doesn’t say if it’s input or output. As the sensors begin to fail one after another on this car I prefer to replace both at the same time if possible. I just can’t seem to find the other sensor.
 

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There is no VSS input sensor, or VSS output sensor

The transmission has :

1 - input shaft speed sensor (PG-A) to watch turbine shaft speed (input shaft) going into transmission for transmission slip, and compare engine speed to shaft speed when converter in lockup for slip

2 - output shaft speed sensor (PG-B) to watch output shaft to verify output shaft rotating at known ratio to input via gear operating in,

3 - VSS - Vehicle Speed Sensor, on final drive unit to register vehicle speed
 

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Discussion Starter · #5 ·
There is no VSS input sensor, or VSS output sensor

The transmission has :

1 - input shaft speed sensor (PG-A) to watch turbine shaft speed (input shaft) going into transmission for transmission slip, and compare engine speed to shaft speed when converter in lockup for slip

2 - output shaft speed sensor (PG-B) to watch output shaft to verify output shaft rotating at known ratio to input via gear operating in,

3 - VSS - Vehicle Speed Sensor, on final drive unit to register vehicle speed
Okay so maybe I need to further my knowledge. What I’m seeing on parts catalogue must be what you’re referring to as the PH-A/B. They look like crank sensors. Anyhow I’ll do some further investigating. On the locations. It strange to me whatever is causing the problem isn’t throwing a code. So I assume it’s the input sensor that is failing. From what I read is that of that sensor fails the speedometer could stop but also wouldn’t throw a code. I’ll go over everything you said and try to pinpoint the issue. I really appreciate your help.
 

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Discussion Starter · #7 ·
If I recall, input shaft speed is P0715, output shaft speed is P0722,, and possibly a P0501 for vehicle speed on the old units.. don't see them anymore due to age / taken off the road
Hey buddy so I haven’t had time to do any diagnostics on the car yet. My wife is off Wednesday and I’ll be working on it then. However today she’s driving to work and now her gas gauge isn’t working right either. So now both the speedometer and the fuel gauge are working intermittently. Does this help pinpoint an issue. Does the fuel gauge work off the speed sensor? Finalize so I can rule it out none of this would be due to a bad VVT solenoid right? The reason I ask is I just replaced it with an aftermarket part the day before this all started. So maybe just a coincidence but if it could be my problem please let me know. I really appreciate all the help you can offer me.
 

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Hey buddy so I haven’t had time to do any diagnostics on the car yet. My wife is off Wednesday and I’ll be working on it then. However today she’s driving to work and now her gas gauge isn’t working right either. So now both the speedometer and the fuel gauge are working intermittently. Does this help pinpoint an issue. Does the fuel gauge work off the speed sensor? Finalize so I can rule it out none of this would be due to a bad VVT solenoid right? The reason I ask is I just replaced it with an aftermarket part the day before this all started. So maybe just a coincidence but if it could be my problem please let me know. I really appreciate all the help you can offer me.
Pull the unit out of the transmission and look at the driven gear, likely ate up

Fuel level whacky on a CM Santa Fe, low fuel light glowing and gauge all over, maybe check engine light, I suspect a P0463 / 61, replace both fuel level sender if never done, and the thick o-ring (packing) for each side when put back together
 

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Discussion Starter · #9 ·
PG-A & PG-B is shaft speed sensors. They used to verify slippage based on mapped gear ratio and engine speed

Speedometer should be function of VSS on transmission in the differential adjacent to right hand side of differential case.

May have to remove air inlet stuff to see down in, but there be a 3 wire connector on top of speed sensor that would fit same place a speedometer cable drive would in old days.. Unplug connector, remove the bolt, and lift that thing out of case,, look at driven gear, they get ate up over time and drive gear wont rotate it

Seen the VSS body itself also burn up inside / see smoke and smell of electric fire.. search speedomter gear here and in the EF Sonata pages, about sure there be pics of parts here somewhere

They wont be on shelf at dealer level, they have to be order from Part Distribution Center to dealer
Okay so I got all the parts in and installed new Hyundai parts. Both shaft speed sensors and the speed sensor with a new drive gear. You were right about the drive gear getting eaten up. It was missing a few teeth. I didn’t smell anything burnt. After installing everything it didn’t work. Took about 30 seconds for the speedometer to start working. Drove around and parked. Turn the car off then started driving again. Still taking a bit before the speedometer starts working. I scanned the car and now have a P0741 torque converter clutch circuit performance or stuck off. Any ideas? New sensor possibly bad? Thank you for your help.
 

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Discussion Starter · #10 ·
Pull the unit out of the transmission and look at the driven gear, likely ate up

Fuel level whacky on a CM Santa Fe, low fuel light glowing and gauge all over, maybe check engine light, I suspect a P0463 / 61, replace both fuel level sender if never done, and the thick o-ring (packing) for each side when put back together
Okay so I tested all the wiring and have power to sensors. I removed the newly installed VSS and noticed the new speedometer drive gear was completely torn up. I reinstalled the old drive gear because it was just missing a little bit of the teeth on the edge. Speedometer is working for now. But what did I do wrong? Why did the new one get torn up. Maybe it wasn’t the correct part. The new one was green wile the original was tan in color. Any advice? Thank you.
 

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Okay so I tested all the wiring and have power to sensors. I removed the newly installed VSS and noticed the new speedometer drive gear was completely torn up. I reinstalled the old drive gear because it was just missing a little bit of the teeth on the edge. Speedometer is working for now. But what did I do wrong? Why did the new one get torn up. Maybe it wasn’t the correct part. The new one was green wile the original was tan in color. Any advice? Thank you.
Match new gear with old for OD and tooth count.. if it got ate up in short time, likely have chopped up drive gear on the differential case
 

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Discussion Starter · #12 ·
Match new gear with old for OD and tooth count.. if it got ate up in short time, likely have chopped up drive gear on the differential case
Yeah so I pulled this dang sticker off the box the new drive gear came in and realized they sent me the wrong part. Sent me one for a manual and not an automatic transmission. They looked so similar and placed a sticker over the part number. I put the old drive gear in and everything is working again. Thank you so much for your help. I really appreciate it.
 

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Discussion Starter · #13 ·
Match new gear with old for OD and tooth count.. if it got ate up in short time, likely have chopped up drive gear on the differential case
So after a day or so it stopped working again. I’m still waiting for the correct drive gear to arrive and I’m hoping that fixes it permanently. I know the original had some stripped teeth at one spot down along the edge. If for some reason it is the gear in the differential, is that tough to replace? Is it metal or plastic/nylon like the dive gear?
 

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So after a day or so it stopped working again. I’m still waiting for the correct drive gear to arrive and I’m hoping that fixes it permanently. I know the original had some stripped teeth at one spot down along the edge. If for some reason it is the gear in the differential, is that tough to replace? Is it metal or plastic/nylon like the dive gear?
Cant answer the drive gear question. We are not allowed to open the case sections, that happens at Hyundai
contracted re-man facility

I have replaced maybe (2) transmission for worn drive gear
 

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Discussion Starter · #15 ·
Cant answer the drive gear question. We are not allowed to open the case sections, that happens at Hyundai
contracted re-man facility

I have replaced maybe (2) transmission for worn drive gear
Got it thanks again. Hopefully that’s not the case than. I was hoping it was as simple as removing the cv axle but seeing it’s a $10 part I assume that means it’s about 1-2 thousand in labor lol.
 

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Discussion Starter · #16 ·
Cant answer the drive gear question. We are not allowed to open the case sections, that happens at Hyundai
contracted re-man facility

I have replaced maybe (2) transmission for worn drive gear
I’m truly sorry to keep bothering you with this. However a new update. I’m still waiting for new driven gear to arrive but according to my wife yesterday on her way home the transmission shifted weird and the speedometer started working again. I assume this is because the transmission uses info from the VSS for proper shifting and when the speedometer started working it shifted accordingly. However if this is pointing to a different issue please let me know. Again I still have no engine light on but I do see a P0741 code stored. This code did cause the engine light to illuminate several months ago but after changing the trans fluid the light or code never appeared again until now when the speedometer stoped however it didn’t cause the light to illuminate, just stored. Not sure if these two issues are linked to each other or not. I can’t thank you enough for letting me pick your brain about this. With money so tight right now I can’t afford a transmission repair.
 
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