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"Scanner can't connect to vehicle"

22K views 21 replies 8 participants last post by  Injuneer 
#1 ·
I've tried with several different scanners and they all say the same thing.
I've checked my grounds but I'm going to check them again. My SES light is on and the car runs but i can't scan for DTCs and I can't collect any data for tuning purposes.
Any ideas?
 
#2 ·
Hi Russ,

I think you post a topic in wich you said that you were changing the LT1 motor for a LS1. Is this is the same car?

Ivan
 
#3 ·
No Ivan. My mods are in my signature.

I had posted about the LS1 swap before but decided against it.
 
#4 ·
Russ,

Try checking for a open (ohms) cable(s) in the harness from the OBD port to the ECM.

Ivan
 
#5 ·
I checked both grounds, verified 12 volts and verified continuity at the data wire from the PCM to the ALDL port.
 
#6 ·
Russ Sorry but, have u checked fuses? Something like the cig lighter fuse supplies the power to the OBD connector too.
Actually only 1.5 cents with the economy today.
 
#7 ·
Russ Sorry but, have u checked fuses? Something like the cig lighter fuse supplies the power to the OBD connector too.
Actually only 1.5 cents with the economy today.
Yes, I checked all the fuses and I'm getting 12 volts to the ALDL port.
 
#8 ·
Have you tried a different PCM? I hope that isn't what it is, but options are running out.
 
#9 ·
I've got an un-tuned PCM out of a 96 Camaro LT1 A4. I guess it wouldn't hurt to hook it up just to see if it connects.
 
#11 ·
What PCM do you have in there now?
 
#12 ·
I have the PCM and harness that was in my car originally. It was tuned by Madtuner for my mods except for AIR delete. The engine is out of a 95 so it doesn't have a crankshaft position sensor. I did install the EVAP solenoid and a 96 Knock Sensor.
 
#13 ·
Did you figure this one out? I've been trying to think of why its not connecting. But if the cig lighter fuse is OK, you are using the 96's OBD-II PCM, you are using an OBD-II scanner, and you have the correctly wired 96 ALDL connector, it should connect.
 
#14 ·
Did you figure this one out? I've been trying to think of why its not connecting. But if the cig lighter fuse is OK, you are using the 96's OBD-II PCM, you are using an OBD-II scanner, and you have the correctly wired 96 ALDL connector, it should connect.
I haven't figured it out yet Fred. I'll be sure to update when I figure it out.
 
#15 ·
Russ, are any of the pins in the ALDL connector pushed, eg. in to far where they won't make contact? Can u see all the metal tabs recessed the same distance from the face of the plug? Just a thought.
 
#16 ·
Another thing I thought of, but I doubt it applies here - I have a ScanMaster LT1 mounted on my dash, and hooked up permanently to the ALDL connector, by splicing to the tan data wire, behind the ALDL connector. I had to add a micro-switch, to allow me to disconnect the ScanMaster from the data wire, because when it is connected, it will not allow another device (e.g. scanner, laptop scanner or programming software) to connect by plugging into the ALDL connector. Any chance you have something connected to the data wire?
 
#17 ·
Another thing I thought of, but I doubt it applies here - I have a ScanMaster LT1 mounted on my dash, and hooked up permanently to the ALDL connector, by splicing to the tan data wire, behind the ALDL connector. I had to add a micro-switch, to allow me to disconnect the ScanMaster from the data wire, because when it is connected, it will not allow another device (e.g. scanner, laptop scanner or programming software) to connect by plugging into the ALDL connector. Any chance you have something connected to the data wire?
Another good idea Fred, but the ALDL and all connections are original.
 
#18 · (Edited by Moderator)
You can move this one to "Resolved" Bob.
Stupid me!

I stumbled across the cause of the problem. I had three PCMs in my garage and somehow got them mied up. The reason scanners couldn't read the DTCs is because I had put the PCM out of the 95 Firehawk A4 in my car.

Put this one in the "Dumbest things I've done" thread.
Here's what happened. During the time I was swapping engines, I ended up with 3 PCMs. One was my original(OBD2), one was out of the 95 Firehawk(OBD1) that I parted out and a 3rd one. I had marked each of them, but, somehow I switched the 96 with the 95 and installed it in my car.
I discovered this when trying out the other PCMs to see if the one in the car was fried. The car ran better and I checked the service numbers and Voilla!
All the pieces of the puzzle fell together after that. The high idle, running rich, the ALDL port not working, etc.

It ran pretty good before other than a high idle and running rich but it really runs good now!
 
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#22 ·
Not the same issue. The 96/97 OBD-2 16-pin ALDL connector has a +12V pin supplied from the cig lighter fuse. The 93-95 OBD-1 ALDL connector does not have a +12V pin, so there is no connection to the cig lighter fuse.

What scanner are you using? There are a couple of high end OBD-1/OBD-2 scanners that will not connect to 93-95, because they are looking for the +12V and there is none.

If you are just trying to pull codes, hopefully you are aware all you need is a paper clip (works on 93 ONLY):

http://shbox.com/1/dlc2.jpg
 
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