1999 3.8 l auto no communication with scan tool - All Things V6 - Firebird Nation

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1999 3.8 l auto no communication with scan tool


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#1 Dwendt1121

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Posted 31 March 2020 - 02:28 PM

I have no communication at all with scan tool. This isnt my first rodeo. Checked the cigar fuse even though scan tool powers up. Its good. Checked for continuity from dlc to star pac all good. Continuity from Star pac to pcm good. Power and ground good for pcm. Have found no corrosion even at sdm. Ipc all good EBCM all good. Just no communication with scan tool. Car starts and runs like a top just need to be able to communicate for state inspection. What am I missing?

#2 sea dog

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Posted 31 March 2020 - 02:44 PM

Have you checked the ground pin of dlc? That's pin # 4. The ground from dlc goes through a splice in the wiring and connects to other ground wires. Download 99 service manual at following link. It will have wiring diagrams, and troubleshooting help. http://www.mediafire.../?40mfgeoe4ctti

 

Are you sure your scanner works correctly? Try it on another obd 2 car and see if all is well with scanner.



#3 Fitch

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Posted 31 March 2020 - 02:45 PM

Sounds like a bad PCM.



#4 Dwendt1121

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Posted 31 March 2020 - 03:21 PM

Tried multiple scanners. Wouldnt the scanner not power up with out the ground

#5 JOE68

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Posted 31 March 2020 - 03:37 PM

I've found that a shorted sensor can cause that.   try unplugging sensors one at a time     when you get the right one it'll power up



#6 ZumpTA

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Posted 31 March 2020 - 03:54 PM

Tried multiple scanners. Wouldnt the scanner not power up with out the ground

 

SeaDog is referring to pin #4 of the port you plug the scanners aldl cable into, not the ground that powers the scanner.


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#7 Dwendt1121

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Posted 31 March 2020 - 04:08 PM

I understand which ground he is referring to. I was asking whether that would effect the powering up of the scanner the same way no power through the dlc does

#8 Dwendt1121

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Posted 31 March 2020 - 04:14 PM

I've found that a shorted sensor can cause that.   try unplugging sensors one at a time     when you get the right one it'll power up

I have power. The scan tool powers up just doesnt communicate with anything. Vehicle runs great.

#9 sea dog

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Posted 01 April 2020 - 03:53 AM

If ground is missing from pin # 4 of dlc, scanner will power up, but can't read pcm.



#10 Dwendt1121

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Posted 01 April 2020 - 09:17 AM

Applied an independent ground to pin 4 and no change. Can hear the bcm clicking when it tries to communicate but still nothing. No communication at all

#11 Fitch

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Posted 01 April 2020 - 10:32 AM

Did you try disconnecting the sensors? A shorted sensor will cause this and the car will run fine. So will a bad PCM with communications failure.






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