How many miles on it?

 

He doesn't know...the odometer stopped working.

 

Burnt pis are usually a sign of too much current. I'd be looking for a short, or, with Hyundais, a bad ground. Something else might be following a path through the sensor to find a ground.

 

I didn't mention it but this is a manual transmission. The next thing I was going to do was take the instrument cluster out and see what drives the speedometer. Maybe something in the instrument cluster is bad. There is another sensor that the harness connects to. Anyone know what that is? It is right underneath the air cleaner box.

 

Sounds familiar. I had a 2009 with manual transmission and at one point the speedometer stopped working. Odometer stopped too. Well, it was intermittent for a while and then stopped completely. My car was pretty basic, no ABS, and like I said it was a manual.
The manual transmission cars have a gear driven speedometer and the gear is plastic. I'm talking about the gear in the output side of the transmission. That was my problem. A local dealership told me that they had seen several cars where the gear just wore out and needed replaced. When a tooth or two gets worn down it can be intermittent. Hit a bump and it may start working a bit, or it turns slower than it should.
Anyway, they tried to order it, but it was back ordered, so I found one on ebay, brought it to them, and they changed it out. I may have been able to do it myself easily, but it was hard to get to. Supposedly it mounts on top of the transmission. It might be easier to reach if you get the car on a lift and reach up to change it. Not sure though, I never watched them do it.

The one I got was for a Kia Rio, but it worked fine. The part number was 4362123550
There are several you can buy on various sites, but not sure which are decent or not:
SLEEVE ASSEMBLY - SPEEDOMETER. SPEEDMETER DRIVEN GEAR (5MT2WD) made by Kia. #4362123550
SLEEVE ASSEMBLY - SPEEDOMETER for Hyundai Accent (2006 - 2010). #4362123550

 

Sounds familiar. I had a 2009 with manual transmission and at one point the speedometer stopped working. Odometer stopped too. Well, it was intermittent for a while and then stopped completely. My car was pretty basic, no ABS, and like I said it was a manual.
The manual transmission cars have a gear driven speedometer and the gear is plastic. I'm talking about the gear in the output side of the transmission. That was my problem. A local dealership told me that they had seen several cars where the gear just wore out and needed replaced. When a tooth or two gets worn down it can be intermittent. Hit a bump and it may start working a bit, or it turns slower than it should.
Anyway, they tried to order it, but it was back ordered, so I found one on ebay, brought it to them, and they changed it out. I may have been able to do it myself easily, but it was hard to get to. Supposedly it mounts on top of the transmission. It might be easier to reach if you get the car on a lift and reach up to change it. Not sure though, I never watched them do it.

The one I got was for a Kia Rio, but it worked fine. The part number was 4362123550
There are several you can buy on various sites, but not sure which are decent or not:


I looked at the pictures of the links you listed. On mine, there is a sensor on the firewall side of the transmission down about 1/2 way. It has a three pin connector. That is the one I replaced. The other possible sensor is right under the air cleaner box and has a two pin U shaped connectors. Both of those connectors are connected thru another connector to the bigger main wiring harness. I don't see a "cable" that goes from either one thru the firewall.

 

found two of the pins on the connector socket going to that sensor were burnt.

Have you checked that there's a 12V power supply & ground on the sensor connector?

 

Nope. I checked all the fuses and they were all good. Not sure which would be the 12v pin. I'll have to check that out.

 

I took the dash out and found that it is all electrical. No speedo cables. Tomorrow, I'll check the voltages on the one on the firewall side and look for the two voltages and ground. I may just pull the sensor out to see if it has the plastic gear on the bottom. I didn't put it in, the mechanic who changed the motor out put the new sensor in. What is the other (oval shaped with orange insulator inside) connector hooked up to? It is the one on top under the air cleaner box.

 

What is the other (oval shaped with orange insulator inside) connector hooked up to?

On a manual gearbox there will normally only be two electrical connectors...a connector with 3 wires on the speed sensor and a connector with 2 wires on the reverse light switch.

 

So maybe it is the reverse light switch. They both go to a larger connector that plugs into a main harness. Does the manual transmission speed sensor have a plastic toothed gear below the sensor? Thanks for your help by the way.

 

Does the manual transmission speed sensor have a plastic toothed gear below the sensor?

I expect it would. All the sensors I've seen on the older Hyundai did anyway.

 

I don't know how Hyundai does it, but I know my '92 Caravans had a speed sensor in the trans, and something like an "ABS ring" inside the trans that caused it to pulse and then the pulses were translated to speed. It was interesting sometimes when these went bad; if it went completely dead the speedo would drop to 0, and it would basically drive OK, albeit the shift points would be higher, but when it just went totally bats and ramped the speedo up to 120 it would hit the fuel cutoff, the van would start to slow down, and then the speedo would drop, then it would go back to 120, etc. I should have won a rodeo trophy for that!

At any rate, other cars use the ABS sensor on one wheel to count the revs and translate to speed. Those are easy since you either change the speed sensor, or, sometimes just cleaning the ABS ring resolves the issue.

Perhaps Sparky can tell us which sensor is used in this car. I have an AT, BTW.

 

On the Accent, I think both MT & AT use a speed sensor on the gearbox to drive the speedo on the instrument cluster. The speed signal for the engine PCM/AT comes from the ABS ECU and vehicles without ABS have a single wheel speed sensor and tone wheel to supply the VSS input to the engine.

The gearbox speed sensor on Hyundai works more like a camshaft position sensor than an ABS sensor. It's a hall effect type sensor that pulls the 5V output on the signal wire from the cluster to ground 4 times per revolution. The more often the signal wire is grounded, the higher the needle on the speedo will move.

 

On the Accent, I think both MT & AT use a speed sensor on the gearbox to drive the speedo on the instrument cluster. The speed signal for the engine PCM/AT comes from the ABS ECU and vehicles without ABS have a single wheel speed sensor and tone wheel to supply the VSS input to the engine.

The gearbox speed sensor on Hyundai works more like a camshaft position sensor than an ABS sensor. It's a hall effect type sensor that pulls the 5V output on the signal wire from the cluster to ground 4 times per revolution. The more often the signal wire is grounded, the higher the needle on the speedo will move.

Hmmm...I wonder if that's the OP's trouble. Something interfering with the field...

 

Haven't had time to take the sensor out yet but will try to get to it tonight. The harness connector was burnt before I replaced the sensor. Thought it would work with the old connector but didn't. Maybe the connector shorted out internally. Anyway, after putting the new harness on, it still didn't work so going to take out the sensor and see if I can get the gear out as they are separate. I'll be back with the results. Still have the old harness and will put a pic of it and the burnt part in next post.

 

Remember to check the voltages on the connector terminals.

 

i had my odometer go blank & ended up having to have the whole cluster replaced. i have an a/t, though. it was weird because it was working fine, but then it stopped randomly after having the stoplight recall done. it was still keeping track of it, though the dealer ended up resetting it to what they had on file, even though i told them specifically that the mileage shown was correct.

 

Worked on the Accent today. Pulled the speedo sensor off and then pulled the gear assembly out. I was hoping the plastic gear was going to have some bad teeth on it but it didn't. I pulled the harness up, turned the ignition on and checked voltages at the connector. I found 12v on the red wire and nothing on the pink and black wires. I then put the connector on the complete sensor/gear assembly and turned the ignition on. I turned the gear while my daughter watched the speedometer and nothing happened. I then took the plastic cover off of the connector to expose the wires where they go to the back of the connector and checked voltages again. 12v on the red and zero on the pink and black. So, question to Autospark or anyone else that knows. Is the 12v to the sensor circuit used to create the signal voltage on the pink wire that goes to the speedometer or is there a voltage generated by the ECM that goes to the sensor on the pink wire? In my mind, the circuit in the sensor uses the 12v to make the 4 or 5v signal back to the speedometer or ECM that then sends it to the speedometer. I replaced the sensor when we had the engine replaced and found the burnt sensor connector (the connector was burnt prior to the new sensor install). Could the burnt connector have possibly caused the new sensor to go bad? The flat side on the sensor has a cover that just snaps off. With the cover removed, you can see a small circuit board inside. Nothing looked burnt in it but that doesn't mean there isn't a problem.

One last thing. I moved the car back and forth with it in first gear with the sensor off and did see the sensor drive post moving so the gear in the sensor housing and the gear in the transmission are working properly.

I'm leaning toward the new sensor being bad.

 

I've never worked on you model car before but I assume it uses the same VSS as the other models that I'm more familiar with (the LC Accent, Getz, etc).

The voltage on the VSS signal wire comes from the instrument cluster/ECU. The sensor works by pulsing/pulling the signal voltage to ground 4 times per revolution, so with the sensor disconnected there should be voltage on the signal wire. Since you have no voltage, check to see if the sign wire is shorted to ground. Obviously, if that's the case the cluster isn't going to see the sensor pulses. If the wire doesn't have voltage and it isn't shorted to ground then the wire is open circuit between the sensor and the cluster.

 

I found a video on YouTube that shows how to check the sensor by hooking the 12v terminal to 12v, neg to ground and then watch the signal terminal with the voltmeter and turn the pin very slowly. That will indicate if the sensor is good anyway. If that works, on to the signal wire tracking. Do you know which pin on the ECM it is connected to?

 

I found a video on YouTube that shows how to check the sensor by hooking the 12v terminal to 12v, neg to ground and then watch the signal terminal with the voltmeter and turn the pin very slowly.

Remember, the sensor pulses the voltage on the signal wire to ground. From what your describing the signal wire in that test is open circuit so there isn't going to be any voltage to display on the meter. What you'd need to do is connect the meter red probe to the 12V supply and the black probe to the signal wire. Maybe then you'd see voltage when the signal wire is pulsed to ground.

 

I removed the sensor this morning marking the 12v pin. Took it in the house and connected my 12v power supply from my Ham radio to positive and the negative side to the negative terminal. Connecting the negative side of my digital volt meter to the negative side and the positive side to the center signal wire, I slowly twisted the sensor shaft and there was nothing. Zero voltage at anyplace the shaft was turned. I noticed the shaft also had some wobble in it and almost felt like it was grinding inside the housing. New one ordered on Ebay for $14. Here is the youtube video. https://www.youtube.com/watch?v=G1XzwZE6n8M

 

Connecting the negative side of my digital volt meter to the negative side and the positive side to the center signal wire, I slowly twisted the sensor shaft and there was nothing. Zero voltage

Like I said above, connecting the voltmeter like that wont produce a voltage on the Hyundai sensor because the sensor output is a ground. So in effect what your doing is connecting both your voltmeter probes to the same terminal. There isn't any potential difference for the meter to measure.

Try connecting your red meter probe to the 12V supply and the black to the signal output terminal and see if you get 12V pulses when you rotate the sensor drive gear. Alternatively, you might need to simulate the signal wire voltage from the ECU by connecting a pull up resistor between the 12V supply and the signal terminal. A 5k or 10k resistor should work. I'm sure a fellow radio guy will have a few of those in his junk box.

73's
GM7OMU

 

I came across this video on youtube that shows how to bench test a Nissan VSS. It is a pull down type sensor just like the Hyundai one. Notice there is no signal output initially until a resistor is fitted between the signal and the voltage supply wires like I described above.

Nissan Micra Speed Sensor Bench Test

 

Put the new speed sensor in today and no change. So, to recap, The positive and center pins on the original cable were burned. Replaced the sensor and no speedo. Bought a new cable and installed with no speedo. Just installed another new sensor and no speedo. The odometer has always displayed the last mileage and doesn't change. This is a 5 speed manual transmission with no anti-lock. What next? Could the obvious short have damaged just the speedometer section of the ECU? Is there a way I could check that thru the port under the dash?

 

Have you checked there is a good ground to the sensor and did you check to see if the signal wire (I'd guess that'll be the pink) is shorted to ground as I advised previously?

Connect your red meter probe to battery positive then (with the ignition switched on) probe the black & pink wires at the sensor and see what you get. If you get 12V on both that suggests the ground is good but the signal wire is shorted to ground.

If you find you have 12V on the black but nothing on the pink that suggests the ground is good but the signal wire is open circuit. In that case check the voltage on terminal 3 of the OBD connector...pinout below. On Hyundai, the VSS is usually also connected to there too. If you have 5ish volts on pin 3 of the OBD connector, you could insert a wire into that terminal of the connector then repeatedly touch the other end of the wire on & off ground. That might make the speedo needle bounce since your pulsing the signal wire to ground just like the VSS should do.

 

Checked ground to sensor, OK. Checked signal wire and 12v wire but don't remember what the signal wire read. It has been about two weeks ago. Seemed OK. I'll get to work on it again Monday and post what I find.

 

So I just went back and read my post on 3-11. With the ignition switch on, I grounded my black negative wire from the VOM meter to ground and probed the red wire with the positive side of the VOM and got 12V. Probed the pink and black and got 0V. Seems I remember probing the black wire checking for continuity and it was a good ground. I'll try it your way Monday.

 

The test you described above certainly suggests there is a problem with the signal wire since you got 0V, but it doesn't tell you if the wire is open or shorted to ground. Testing it again with reference to B+ will tell you if it's shorted to ground (you'll get 12V is it's shorted).

 

Ok, so now, besides #1 and 2 ignition coil going bad, I checked the ground at the sensor plug as you stated and it showed -11.43v which indicated it is good. Checked the signal line and 0v with red on positive and probed with black. No short. Went into the obd plug and checked pin 3 and found 11v. Shorted it to ground and the speedometer went up to 20mph and back down. I could see that the speedometer would come active when I turned the ignition on by moving slightly. I'm assuming then that there is an open somewhere in the sensor wire between where the new sensor plugs into the harness and where ever it goes, maybe ecm. Do you have a diragram autospark?

 

I'm assuming then that there is an open somewhere in the sensor wire between where the new sensor plugs into the harness and where ever it goes, maybe ecm. Do you have a diragram autospark?

Well done for managing to properly diagnose the cause of the speedo failure. It's just a matter of figuring out where the wire has gone open now. Sorry but I don't have any diagram specific to your model. Perhaps if you PM ikilledbarbie he will be able to help you out with that. He's the forum's MC Accent guy.

Us auto sparks often have to diagnose faults on cars without any diagrams though. There's no way you can have diagrams for every car that's out there. The way to trace the break is to simply probe the speed signal wire with your voltmeter at accessible points along the harness until you get a voltage reading. Once you have voltage you will know the break in the wire must be between the last two spots that you probed. More often than not you usually end up having to do it that way even when you have a diagram if you want to pin point exactly where the break is.

 

If I knew which pin it was on the main connector on the ECM, I would just run a jumper wire from that to the point where the new sensor wire connects to the main harness on the right side of the engine. I think it goes into the wire bundle that goes across the top of the engine that you have to take loose to get the spark plug coils out. I haven't been able to spend alot of time with it because of a chest cold but will try to track it down. I'll probably be so fed up with it at that point that I'll sell the car. Tired of replacing coils. Got one of the replacements from the Ebay seller I got the original 4 from, and bought one from O'Rielly's today to get it running again. The plan is to buy two more from O'rielly's and then send the four back to the Ebay seller for a refund. The original one from O'Rielly's is still working. I also replaced the spark plugs with regular cooper type that several have suggested to do. Leaving the top plastic "make it look pretty" cover over the valve cover as others have said the coils will run a little cooler that way. Can't hurt. It was interesting when I called the Hyundai dealer and talked to the parts guy. He said he sells coils all day every day for the Accent. I talked to a woman service adviser and she said they aren't a problem. Who to believe. haha

 

The speed signal that goes to the engine PCM is a totally different circuit. That signal comes from the ABS, or a wheel speed sensor if your car doesn't have an ABS system. The VSS on the gearbox is only for the instrument cluster. If you want to string a wire to make the speedo work string one from the sensor to the OBD connector. Personally, I'd try and find the actual break. If one wire has been damaged you might find that there are a couple others about to break at the same point in the harness too.

COP ignition coils are pretty useless regardless of what brand of car you buy. I was a tech in a VW dealership until recently and we were always having to replace coils on those too. VW even extended the warranty on them to 5 years because there were so many failing. I wouldn't advise buying cheap Chinese pattern parts though. It's better to stick with OEM coils in my experience.

Scottie.

 

It is my belief/thought that what ever caused the original wiring harness connector (that connects the speed sensor and backup light switch that the third leg goes to the main harness) may have causes it to burn the signal wire someplace else. That signal wire is the wire I want to find the other end to so I can check the continuity of.

 

Got your pm. Here are the diagrams... need anymore help just ask.