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No communication between OBD2 scanner and vehicle

Tiny
96MBE320
  • MEMBER
  • 1996 MERCEDES BENZ E320
  • 120,000 MILES
Each time I have tried scanning my vehicle for codes using the OBDII scanner, there is a message on the scanner stating that it is unable to communicate with vehicle. There are lots of issues with my car, but I am not able to correct them because of the OBDII issues. I do not want to continue to buy parts without knowing what the specific issue is. I will appreciate any advice or any help.
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Saturday, August 31st, 2013 AT 9:31 PM

27 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,690 POSTS
Does the check engine light work? It should come on with the ignition key in the on position. If not please check the system fuses 17, and 15. Also check the ALDL for corrosion and clean up the terminals as needed.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Here is a wiring diagram which pertains to most cars showing the power going to the ALDL connector.(below) If anyone reading this needs the wiring and the fuse ID to there car please send there request here.

https://www.2carpros.com/questions/new

Also, check to see if the scanner works on a different car.

We are here to help and tell a friend.

Best, Ken
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Saturday, August 31st, 2013 AT 10:20 PM
Tiny
96MBE320
  • MEMBER
  • 8 POSTS
No. The CEL does not come on at all, and the scanner will not read. I have traced most of the wires, and I did not notice any break. It was just something that happened, all of a sudden. I also checked the fuses.
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Monday, September 2nd, 2013 AT 10:04 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,690 POSTS
Have you checked computer fuses and relays? If all are good it sounds like the computer could be bad. Test with the key in the "on" position.

Check out:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

and

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Please get back to me, I would like to resolve this issue with you. :-)

(Additional user comment) If scanner cannot connect and CEL does not come on, the problem is most likely the ignition switch.
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Tuesday, September 3rd, 2013 AT 10:09 AM
Tiny
96MBE320
  • MEMBER
  • 8 POSTS
I have checked all the fuses and they are all in good working order. The question is, which of the computers needs replacing? Thanks guys, you are great! Look forward to a donation because I may need you in the future.
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Wednesday, September 4th, 2013 AT 9:45 AM
Tiny
96MBE320
  • MEMBER
  • 8 POSTS
Read the links, but I do not know if my car has any relay. I have never seen anything other than the regular fuses. Where will I find them?
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Wednesday, September 4th, 2013 AT 9:51 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Here is a diagram for your car on where the components are located. It sounds like it could be a computer problem by itself, but more testing is needed. Also, if the check engine light itself is out it will cause this problem.
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Wednesday, September 4th, 2013 AT 10:23 AM
Tiny
96MBE320
  • MEMBER
  • 8 POSTS
I have ordered an adaptor for the data link connection. I will have to try reading it. What other testing were you recommending, and how do I make a donation on your site?
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Wednesday, September 4th, 2013 AT 6:23 PM
Tiny
96MBE320
  • MEMBER
  • 8 POSTS
A physical inspection of the relay module did not reveal any damage or a breakage in the circuit board, and all the four fuses are in good condition. I did not remove the engine module.
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Wednesday, September 4th, 2013 AT 7:25 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,690 POSTS
If all electrical sources are good, the only test remaining is a pin to pin check with a wiring schematic while using a volt meter to check each wire. If all checks okay, the only thing left is the engine control unit itself, ECU. They do not go out very often, but it does happen. Please let me know what you find, I want to get this problem fixed for you. :-)
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Thursday, September 5th, 2013 AT 8:31 AM
Tiny
96MBE320
  • MEMBER
  • 8 POSTS
I will do that, and inform you of the results. If I may ask, what is the function of this part (210-545-0132 T/LLR idle control module)? I thought that might be one of the problems.
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Thursday, September 5th, 2013 AT 9:17 AM
Tiny
KEN L
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It is part of the ECU function which is integrated into the main computer ECU in later models.
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Thursday, September 5th, 2013 AT 8:08 PM
Tiny
96MBE320
  • MEMBER
  • 8 POSTS
Good day,

I have tried diagnosing the car with the round OBDII scanner, and I am receiving the same communication message. At this point, I am wondering what to do. I will also appreciate it if you are able to tell me which of the computer needs replacing, may be with the part number. Thanks for answering my question. I will post my experience(s) once I get it right.
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Friday, September 13th, 2013 AT 1:24 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Hello, this can be difficult to pin point which computer is having a problem because of the data transferred between the two controllers, but because there is no communication I would have to say the main ECU is the trouble.
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Monday, September 16th, 2013 AT 9:45 AM
Tiny
CORVAIRWILD
  • MEMBER
  • 3 POSTS
Hi, I have a 1999 E320 Mercedes, 210 chassis. It has very high miles, 436,000, but a much newer engine, it is due for its yearly safety emissions inspection. The check engine light has been on for the last six months. All was well until recently it started having extended crank times, and then the last few days it's been stalling upon cold startup but it restarts right away. So I bought a Torque Pro plug in ELM 327 OBD2 scanner for my phone, but when I plug it in there is no communication. So I went to FLAP and they plugged in their scanner, and it says no communication, just like mine. So I looked at the plug in under the dash, and only four the many holes actually have contacts. But what could the problem be? The car is a two owner before me, and is really original and untouched, nothing has been hacked in any way.
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Sunday, October 2nd, 2016 AT 8:57 AM
Tiny
KEN L
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Hello Corvairwild,

Do not worry about the connector not having that many pins in it most have pins missing which is normal. Try using the scan tool on other car first to see if it is working before checking the Mercedes. If it works check to see if the check engine lights works.

Please let us know what you find so it will help others.

Best, Ken
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Monday, October 3rd, 2016 AT 8:50 AM
Tiny
CORVAIRWILD
  • MEMBER
  • 3 POSTS
I tried my ELM327 Bluetooth, no connection, AutoZone tried theirs, same, friend tried his, same, a friend plugged in his Snap On Solis $4,000.00 scanner, brought up EGR code. I found a dried and split vacuum hose. I replaced it and another friend with a brand new $9,700.00 Snap On scanner was also able to read my codes. A new one appeared, intake air temperature, but that was probably a not well connected plug I had just removed and replaced. He turned off the lamp, and I have not had a chance to check the intake temperature plug, and it is raining now and I will be putting the car away for the winter in a couple of days.
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Friday, October 21st, 2016 AT 8:05 AM
Tiny
CORVAIRWILD
  • MEMBER
  • 3 POSTS
I also removed the EGR Valve and it was minimally blocked with slimy residue, not a problem as it was ten percent blocked. The car occasionally stalls upon cold startup, and sometimes has extended crank time. I think that may be a weak fuel pump or bad crank sensor. Just a guess
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Friday, October 21st, 2016 AT 8:09 AM
Tiny
KEN L
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  • 47,690 POSTS
Hey CORVAIRWILD,

Good find on that problem, on the older Mercedes it sounds like the more expensive scanner is the only thing that will work on some models.

Best, Ken
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Friday, October 21st, 2016 AT 4:10 PM
Tiny
LIMPIMPG
  • MEMBER
  • 8 POSTS
Make sure scanner or app is compatible with Euro models. Usually have to pay extra for the software for Euro models.
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Sunday, November 27th, 2016 AT 12:13 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Great additional information to the thread.

Nice work

Best, Ken
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Monday, November 28th, 2016 AT 9:18 AM

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