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Jerry Newton
Jerry Newton, Chevy Technician
Category: Chevy
Satisfied Customers: 4412
Experience:  ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
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2006 Chevy Cobalt cant pass emissions. The obd won't communicate

Customer Question

2006 Chevy Cobalt cant pass emissions. The obd won't communicate with the scanner. I recently replaced the battery, tried to run the drive cycle they recommended and nothing. I checked the cigarette light fuse and it's still good. Any ideas?
Submitted: 1 year ago.
Category: Chevy
Expert:  Jerry Newton replied 1 year ago.
Is there power at pin 1 of the DLC or no?
Customer: replied 1 year ago.
How can I check? Is it the pin on my OBD with the red and white wire?
Expert:  Jerry Newton replied 1 year ago.
yes, red and white wire. I'm sorry, I missed a key when I typed that, it's pin 16, not pin 1. Use a test light attached to ground and see if it lights up when you touch that pin on the DLC.
Customer: replied 1 year ago.
It doesn't light up, I was checking all of them just now and that's the only one that doesn't.
Expert:  Jerry Newton replied 1 year ago.
That should be the only pin with power on it, do you have power at other pins?
Customer: replied 1 year ago.
I do have power with the others while the car is off and keys not in. Some are dim and another lights up bright. The only one that doesn't light up is pin 16
Expert:  Jerry Newton replied 1 year ago.
I am curious which one lights up bright. Nonetheless, the pertinent problem here is that the red/white wire is not lit up. Lighter fuse has power across it? Touch a test light to the top of the fuse and verify it's hot on both sides.
Customer: replied 1 year ago.
Pin 4 & 5 light up the brightest. And the light doesn't light up on either side of the fuse when I test it with the test light. However I have a test fuse and it lit up. Just didn't light up with the test light. Both of my cigarette lighters work inside my car though.
Customer: replied 1 year ago.
I pulled out the fuse and tested it with a fuse tester and it lights up. But when it's back in the fuse box and trying to test both sides on top of the fuse with the test light it doesnt light up.
Expert:  Jerry Newton replied 1 year ago.
Pins 4 and 5 are ground connections. If you have a test light connected to ground, and you're lighting it up when you touch 4 and 5, there is something wrong with this picture.
Expert:  Jerry Newton replied 1 year ago.
Your test light alligator clip is attached to ground, yes? Not battery positive?
Customer: replied 1 year ago.
Right it's attached to a ground not something positive.
Expert:  Jerry Newton replied 1 year ago.
Test your test light on the battery. I do this often, just to make sure things are working correctly. When you touch battery positive, your test light should light up. Does it?
Customer: replied 1 year ago.
Weird it doesn't. I just bought this today.
Expert:  Jerry Newton replied 1 year ago.
OK, we're being owned by a bad test light. Don't worry, it happens, that's why I test them regularly when my results don't make sense. Let's get a new test light, test it across the battery to verify it works, and try this again.
Customer: replied 1 year ago.
Ok will do. Give me a few minutes
Expert:  Jerry Newton replied 1 year ago.
Sure, let me know when you're ready.
Customer: replied 1 year ago.
Back, everything works as you mentioned. Pin 16 is the only one that lights up. The fuse for the cigarette lighter also lights up when I touch both sides.
Customer: replied 1 year ago.
Any other ideas?
Expert:  Jerry Newton replied 1 year ago.
Do you have ground on pins 4 and 5? Reverse the connection on the test light, alligator clip to battery positive, touch those two terminals, light should light up.
Customer: replied 1 year ago.
I do, they light up.
Expert:  Jerry Newton replied 1 year ago.
OK, do you have a scan tool to plug into the car? Does it work now?
Customer: replied 1 year ago.
No I don't have a scan tool, I take it to emissions where they scan it and that's where it comes up that it can't communicate with my OBD. So testing everything today nothing has changed with my car so chances are when I take it back it still won't read it. Guess I'm back at square one, cigarette lighter fuse is good. Power on pin 16 works and ground on 4-5 pin work with reverse testing. I'm back to my original question right? Anything else it can be? Maybe more drive time/cycles?
Expert:  Jerry Newton replied 1 year ago.
No, it has to communicate regardless of drive cycles. What I'm wondering is whether you inadvertently fixed the problem by moving fuses around and whatnot. Emissions failure due to non communication is almost always a power or ground issue, and plugging in a code reader or anything that runs off that DLC will predict whether they'll have a problem at the inspection station or not.
Customer: replied 1 year ago.
So I'll go tomorrow if they are open to retest and if so I'll let you know what happens. If they are not then I'll go Monday and let you know.
Expert:  Jerry Newton replied 1 year ago.
What you can do in the mean time is stop by an Advance Auto or Autozone, or other parts store. They usually have a scan tool you can use, all you want to do is plug it in and see if it reads the data. If it does, then you're good. You could do that today, probably.
Customer: replied 1 year ago.
So I went and nothing read. Came back and checked all my fuses and it appears the fuse to my airbags was blown. I replaced it, went back again and it read! So I finally passed my emissions. Thanks for your assistance.
Expert:  Jerry Newton replied 1 year ago.
Excellent! Thanks for the update.