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When I hook up my Actron scanner tool to my OBD port, it comes back with a No Data Link

Tiny
KARTZ
  • MEMBER
  • 1999 DODGE TRUCK
  • 5.2L
  • V8
  • 4WD
  • MANUAL
  • 274,000 MILES
Message. My scanner works on all my other vehicles, (except my 1991 Bronco-that needs it's own scanner).
I changed the dashboard completely about 3 years ago because they all fail in Dodge trucks but I also had other issues with the HVAC that I won't go into except to say that the previous owner did a real hack job on an attempted repair of the heater core and blend door actuator. They cut the shell in half at the bottom and tried to reassemble everything with foil tape. Didn't realize any of this until after buying it. Just wondering if I missed a wire, connector. Can't remember if I ever scanned it before replacing dash. Haynes Manual shows diagram that says pin 45 is data transmission, pin 46 is data rec. I'm guessing that the PCM is receiving data as all the idiot lights go on in key on mode and I have a check engine light on-just no communication to obd port. Should there be voltage signal on that terminal at the port? If so, how much and which terminal at the port would be the one to get the data for the scanner at the obd connection?
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Monday, September 2nd, 2019 AT 12:05 PM

11 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon,

There is a serial data lines at the connector that need to be checked. I attached a picture of the connector and need you to test the ohm reading at pins 6 and 14. Red end in 6 and black lead in 14.

Roy
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Monday, September 2nd, 2019 AT 1:07 PM
Tiny
KARTZ
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Hey Roy. Thanks for getting back with me. So after hooking up my leads every way I could think to try, direct probe, back probe, pin probe, key off, key on, I get no resistance readings. Stays on "1" which with my meter is over range or not connected.
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Wednesday, September 4th, 2019 AT 3:32 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
If you do not get a reading of 57 to 60 ohms on those 2 pins, going in from the front, there is an issue with the serial data line.

Roy
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Wednesday, September 4th, 2019 AT 3:57 PM
Tiny
KARTZ
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  • 6 POSTS
Thanks. So my 6-pin is green. The 14-pin is white with light purple. I've been looking for schematics to see where I can do a continuity test on those wires. There must be other connections in line to the PCM because nothing matches there. Do you know if that is correct? Also, in my initial contact to you, I was wrong. The manual actually has pin 45 at the PCM as data link rec. And pin 25 as the data link transmission. I was just writing it at first off the top of my head. So yea, I'm not getting any read from those two pins, 6/14, that is. As far as the troubleshooting goes, I'm guessing that's what you're suggesting is to trace the wires? I hate doing that! I mean I can, I'm just not good at it.
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Wednesday, September 4th, 2019 AT 6:04 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Those wires go to all the modules that communicate by serial data.

The fact there is no ohms reading indicates an open circuit somewhere with the modules. It is not as easy as ohming out wires at all.

Roy
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Wednesday, September 4th, 2019 AT 6:16 PM
Tiny
KARTZ
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Okay. So my next move is what? Bring the dash down and/or apart and start backtracking from the OBD connector.I still have most of the old wiring harnesses from the original dash in a pile somewhere. I thought I had put everything from that assembly into the one I replaced it with that didn't have what the original had. Am I on the right track? Please advise. Again, thanks for your responses. It's more than one get's from most other information avenues.

Kartz
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Thursday, September 5th, 2019 AT 4:04 PM
Tiny
ASEMASTER6371
  • MECHANIC
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I would inspect the harness for any damage. Finding wiring issues is time-consuming and frustrating. Try disconnecting the modules and retest to be sure one of the modules is not pulling down the signal.

Roy
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Thursday, September 5th, 2019 AT 4:32 PM
Tiny
KARTZ
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Right, but to do that you're saying to drop or remove the dash. Right? That is the part I said I do not like. That takes gobs of time and tracing stuff down is the part I said I'm not good at. But I would rather that than be twisted up on the floor bed between seat and firewall with 4X4 shifter up the.--That is, if that is what you are recommending needs to be done to find bad harness/module. Unless you have a better way to do it?
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Thursday, September 5th, 2019 AT 5:11 PM
Tiny
ASEMASTER6371
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I wish there was a better way of doing it. It would have saved me a lot of time over the years.

Roy
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Thursday, September 5th, 2019 AT 5:18 PM
Tiny
KARTZ
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Well, again thanks. For me, it will be a matter of finding the time to do it unless of course issues turn my truck into a non-running pile of matter. Then, I guess, necessity would trump any excuses I might try to convince myself of to not getting it done. I'll get back with you when I find anything out. Might be a couple of weeks. So, carry on fellas!

Kartz
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Friday, September 6th, 2019 AT 12:44 PM
Tiny
ASEMASTER6371
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You are welcome.

Keep us updated.

Roy
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Friday, September 6th, 2019 AT 3:21 PM

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