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2005 Santa Fe emissions machine would not communicate with car computer

25K views 35 replies 10 participants last post by  Thedude724 
#1 ·
I own a 2005 Santa Fe 3.5L. I took it to 3 different places for emissions but was told their machines could not read the car computer - no code, no error - basically they wouldn't shake hands. I have checked to see if there were any blown fuses but there was none. A new radio was installed last October so I removed the new radio, reinstalled the old one just to see but no success either. I took it to the dealership and after waiting for 3 long hours, I was told they had no idea either. The car runs great without any issue and the only suggestion they had was to replace the computer at $1,500.00 but there would be no guarantee either. Anyone has any idea what could be wrong? Thank you in advance!
 
#2 ·
Nice of your dealer to offer to relieve you of $1,500 with no guarantee that your fault will be fixed.

What I suggest you do before parting with your $1500 is get a voltmeter and check that you have a power supply & ground to the diagnostic connector (the DLC).

First connect the black meter lead to a good ground then touch the red probe to pin 16 of the DLC and make sure you get 12V.
Next, with the red probe touching pin 16, touch the black probe onto pin 4 then pin 5 and again make sure you get 12V on each.

Scottie.
 

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#3 ·
USA model, the sunroof fuse drives the "+" at the DLC..

-- " I have checked to see if there were any blown fuses but there was none." --


What did we use to check with ??

This is how we test fuses and circuit --
 

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#4 ·
Thank you both for your replies!

I also use the multimeter to test the power.

Scottie, I followed your direction and retested the power (although I had already done so previously) just to make sure but everything is normal. What else can I do from this point? I am willing to pay $1,500 to have the computer replaced but without guarantee, I am hesitant to do so. My car needs to pass inspection by the end of June or I would not be able to drive it on the road. Any help would be greatly appreciated!
 
#6 ·
topmack, does your vehicle have a factory immobilizer system?

On UK models the K-line (the communication wire between the DLC and the engine PCM) doesn't route directly between the engine PCM & the DLC. It first passes through the immobilizer control module (the ICM). Inside the ICM there is a relay that should switch the K-line from the engine PCM over to the wire coming from the DLC when the scan tool is connected (see attached). If the relay fails to switch over for whatever reason, the scan tool can no longer communicate with the engine PCM. You could re-establish the link by manually bypassing the ICM.

I don't know if that is relevant to your vehicle but I think it's worth looking into before trashing the $1500 PCM.

Scott.
 

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#8 ·
What could be wrong? You haven't indicated a problem except you can't get the code reader to connect. Sounds to me like you need to stop disconnecting power to the ecu. Every time you hard boot the ecu, it takes numerous drive cycles for the thing to completely reset emissions data and make a reading for the code reader. I'm sure the dealer would be overjoyed to replace your ecu for $1500, they make a fortune replacing a part with a 5 minute install. I got an idea... fugetaboutit.
 
#9 ·
I got an idea... fugetaboutit.
Can you do that though?

We have different emission tests here in the UK so I may be wrong here, but in the US don't they need to connect a tool to the DLC as part of the emissions test? Surly if they're tool can't link with the engine PCM, the car wouldn't be able to pass the test?

topmack, have you checked to see if there is any voltage on terminal 7 of the DLC when the ignition is switched on? If you don't have any voltage present then another thing you could check is the K-Line on the check connector behind the driver's dash trim. There is a K-Line terminal on Pin 7 of that connector too. It's a white male connector with, usually, 8 terminals...see attached. If you find you have no voltage on terminal 7 of the DLC but 10~12V on pin 7 of the check connector, you could try linking a wire between the two connectors and see if that restores comms with the engine.

Scott.
 

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#12 ·
Thank you guys for the replies! Scott, you are correct! if the tool can't link with the engine PCM, the car wouldn't be able to pass the test. The diagram you attached is a 2002 Kia diagram. It doesn't look the same as the Hyundai's. Did I misunderstand you?

To answer your question, jsinton, I did not keep disconnecting power to the ECU. In order to troubleshoot it, I had to test to see if there were any blown fuses. And then the aftermarket radio question came up, so I had to disconnect the radio to see if that was the issue. After that, I took it to the dealer to have them troubleshoot it. I do not wish to pay the dealer $1,500 either; that is the last thing I want to do, especially when the car runs great.

I do appreciate everyone for their replies!
 
#14 ·
Scott,

Although the diagram is not the same, I am following your instructions and test your theory. I will post the outcome as soon as I am done. I truly appreciate someone like you who takes the time to answer other people's problems. I will keep you posted.

Tom
 
#15 ·
Scott,

I checked and there was no voltage on terminal 7 of the DLC when the ignition was switched on. I then proceeded to check the K-Line on the check connector behind the driver's dash trim. Pin 7 showed 8.6V but not 10-12V but I went ahead and linked a wire between the two connectors, as you suggested. I then connected the OBD scanner and viola, it said "pass". I immediately took the vehicle to the emissions place and it PASSED the inspection!!!!!

I cannot thank you enough for your help. Your BS evidently wasn't BS; you have saved me $1,500.00! I do have one more question if you don't mind. What was in the circuit that could have caused the voltage not be on the pin? Just wondering if I need to find a permanent fix to the problem, but again, THANK YOU!

Tom
 
#17 ·
I cannot thank you enough for your help. Your BS evidently wasn't BS; you have saved me $1,500.00!
I'm glad I was able to assist you, Tom. It makes me wonder what is going on in the Hyundai dealerships these days though? I don't see why they couldn't figure out how to do that when they have the car right there in front of them yet I could sus it out from half way round the globe. There was a guy on another thread the yesterday who had a problem with his Elantra and his dealer had it for more than two hours and could figure out why the clock & interior lamp wouldn't work. I told him to replace the ROOM LP fuse...sorted! honestly, what is going on?

I do have one more question if you don't mind. What was in the circuit that could have caused the voltage not be on the pin?
The two K-Line pins on the two connectors are linked in the vehicle loom. The only difference is on cars that have the factory immobilizer. The K-Line on the 16 pin DLC routes through the immobilizer like I explained before as where the K-Line on the 10 pin check connector routes direct from the PCM. So, if your car doesn't have an immobilizer, I don't know why there should be no voltage on the K-Line the 16 pin DLC. Either way, you can simply link the two connectors permanently. I don't see any problem with doing that.

Regards.

Scott.
 
#18 ·
Scott,

I also asked the same question over and over again. These are mechanics who should possess the knowledge that I don't have but the only solution they could offer was to replace the computer. Anyway, I will leave it the way it is if you think it's ok. I truly truly appreciate your assistance!
 
#20 ·
No, clearly it wouldn't have solved the problem. Not that they would care too much. I'm sure they make a decent mark up on the replacement PCM. And no doubt they would want to charge you even more labour to try and diagnose what the real cause of the problem was.

All the best.

Scott.
 
#21 ·
Scott,

I agree with you! My next project is to fix my wife's 2007 Santa Fe. She had a fuel door release problem; you could push the button all you wanted but the fuel door wouldn't open when she needed to get gas. I have replaced the fuel filler door lock actuator. Now it works but it only works when it pleases, like it has its own mind (same as one of her car doors that only locks and unlocks when it feels like it).
:( Now I have taken care of our daughter's 2005 Santa Fe with your help, I need to jump back to taking care of my wife's car. Have a nice day!

Tom
 
#24 ·
Hi there Rebel.

I read your original thread but from what you've said there, it sounds like you have some other problem since the scan tool can communicate with the engine PCM on your car.

If you have a factory immobilizer and the scan tool can't communicate with the engine PCM what you can do is disconnect the immobilizer ECU and link the 2 'K' lines with a wire link to see if that gets the scan tool and the engine PCM talking. There are two 'K' lines on the immobilizer ECU, one coming from the DLC and the other comes from the engine PCM.
 
#25 ·
If you have a factory immobilizer and the scan tool can't communicate with the engine PCM what you can do is disconnect the immobilizer ECU and link the 2 'K' lines with a wire link to see if that gets the scan tool and the engine PCM talking. There are two 'K' lines on the immobilizer ECU, one coming from the DLC and the other comes from the engine PCM.
Thanks for the reply Scott. I appreciate your help. How do I disconnect the immobilizer? Just pull the white cord out? I assume that will disconnect the alarm and the key fob. Will the car start ok still?
Thanks!
 
#28 ·
I know this is an Old thread,
I am having the same issue with my 2004 V6 Sonata
No check engine light but when I plug scanner in/take it to emissions there is no comm from data link.
Voltage at DLC to power scanner but no Comm
DLC pin 16 12.6 volts
I am only getting 7.8 volts at pin 7 with key on
I am not sure what wire pin on ECU is pin 7 on DLC in order to make a jumper.

Any help with this would be appreciated.

I am not aware of the car having a factory immobilizer there is no key fob to unlock doors.

There was a aftermarket alarm on car when I bought it but it was not functioning and I’ve removed it with no I’ll effect to car running/starting.
 
#31 ·
No check engine light but when I plug scanner in/take it to emissions there is no comm from data link.
Sounds to me like your engine computer isn't powered up. No power = No CEL and No Comms.

Thedude724 said:
Isn’t pin 7 “K-line” supposed to have battery voltage when key on?
I thought that’s what I read.
No, 7.8V sounds OK. Read post #15 on this thread.
 
#29 ·
Pin 7 is for K line communication.

ISO 9141-2. This protocol has a data rate of 10.4 kbaud, and is similar to RS-232.
ISO 9141-2 is primarily used in Chrysler, European, and Asian vehicles.
pin 7: K-line
pin 15: L-line (optional)
UART signaling (though not RS-232 voltage levels)
K-line idles high
High voltage is Vbatt
Message length is restricted to 12 bytes, including CRC

ISO 14230 KWP2000 (Keyword Protocol 2000) used by most European and Asian manufacturers.
Alfa Romeo, Audi, BMW, Citroen, Fiat, Honda, Hyundai, Jaguar (X300, XK), Jeep since 2004, Kia, Land Rover, Mazda, Mercedes, Mitsubishi, Nissan, Peugeot, Renault, Saab, Skoda, Subaru, Toyota, Vauxhall, Volkswagen (VW) since 2001, Volvo to 2004
pin 7: K-line
pin 15: L-line (optional)
Physical layer identical to ISO 9141-2
Data rate 1.2 to 10.4 kbaud
Message may contain up to 255 bytes in the data field
 
#33 ·
Start with a wiring diagram and various branches for the comm. Look at various sensors/modules connectors they run through, do visual inspection for frayed or oxydated wire. Once you see everything your comm runs through, start unplugging one sensor at a time to see if it gets restored. There can be something pulling the network down due to a short. It's a needle in a haystack but part of diagnostic process.

Sent from my SM-G930P using Tapatalk
 
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