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George H.
George H., ASE Certified Technician
Category: Pontiac
Satisfied Customers: 18761
Experience:  ASE Master Tech 15+ years
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Where is the fuse that provides energy to the OBD port

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Where is the fuse that provides energy to the OBD port located? I have plugged my Innova 3120D scanner into the ODB1 port and the scanner does not turn on. One of the things the ODB scan tool manual gives as a reason for this is the port is not energized. Can you please tell where that fuse is located so I can determine if that is the cause? It appears that all the fuses in the car are functional. I have not lifted the hood to access the fuse box there. Is that the location of the OBD fuse and it so can you give me a diagram of the box and/or the OBD fuse number?

Hello I will help,

This port is not powered. You need power from the scanner to read codes.

Does the tool turn on without it plugged in?

Click here for a link to the owner's manual for the tool

Have you checked the batteries?

Customer: replied 8 months ago.
The scanner has brand new batteries all showing 1.5v on the voltage meter. The scanner accpts programming for the year and 8th digit of the vin. When DTC's are asked for, the scanner says absolutely nothing even after being given 5 minutes to gather info. Likewise it has nothing to say when asked to clear the code. It is as if the OBD port has no power.

So the scanner does turn on? Do you have a generic OBD setting so you don't enter the VIN?

The OBD port does not have power, can you use a paperclip in the A and B pins of the port to short them then turn the key on and watch the check engine light for flash codes?

Page 90 of the manual explains the GM port

Customer: replied 8 months ago.
I have followed the instructions on page 90-94 if the manual and never get the "one moment please" message or any other message. Nothing happens. Nothing appears on the screen. It is as if the OBD port is not linked to the tool even though the tool in firmly inserted in the port. Doesn't something have to power the port?

I understand that, nothing powers the port. The power is provided by the tool.

Can you try the paperclip in the A and B pin holes?

Do you know which they are? Don't guess.

Click here for diagram

Customer: replied 8 months ago.
According to what I saw on a Youtube, the A and B pin holes are the top row two right most holes whose locations are being described assuming I am in the driver's seat position. Is that correct? According to the Youtube I saw, at first the dash should flash 12 three times and then flash the codes. Is that correct?

Can you look at the diagram I posted above so you can see which are the A and B? Just click where it says "Click here"

Yes, a clear code will be output at the beginning and end of the code flashes.

Click here fo video

Customer: replied 8 months ago.
No click here appeared, George.

How about the last video I posted? What are you communicating on?

Customer: replied 8 months ago.
I'm on a laptop. However, I have gotten no links or anything to click.

Can you see the text that says "Click here for video" in my post above? Click there.

Customer: replied 8 months ago.
I got the link for the download of the owner's manual, but no links have come to me after the owner's manual link.

Can you see the text in my post above?

Customer: replied 8 months ago.
Here is now the text came to me 'Can you see the text that says "Click here for video" in my post above? Click there.' See, there is no link.

No there is no link in that post, it says see the post above that one.

Customer: replied 8 months ago.
The only link that is in this whole conversation is the one for the owner's manual which is in blue. No other blue links or underlined text has appeared.

There are two links below that. One for a diagram of the port and one to a video of testing using the paperclip. Here they are again

Click here for diagram

Click here for video

It is past my bedtime so try to get it to flash codes, if it will there is nothing wrong in the port the problem is in the tool. I will look to see if you were successful tomorrow.

Customer: replied 8 months ago.
Okay, now I have links and I will look at them

Good, let me know what you find, if it won't flash codes I can help you with that later.

Customer: replied 8 months ago.
Well George, I took the fuse cover shield off to make sure I could see the OBD holes clearly. I created the paper clip U shaped connector with fairly long legs on the U and placed the legs in the A&B holes of the OBD port. I then turned the key to the on position. I did this three times and repositioned the paper clip a couple of times. It won't flash codes and considering its lack of response to the Innova, I'm not surprised.
Customer: replied 8 months ago.
I have described the situation as no power to the OBD. Well if it's not a power problem, it sure is a connectivity problem. What is the solution for whatever it is?
Customer: replied 8 months ago.
When we continue this conversation, I would like to switch to a live phone call. There are some weird things going on here. Even though I did not get the paper clip to give back any codes, when I came back in and turned on the Innova, there were codes in it even thought I could not get those codes to show while connected to the OBD port. These could not be left over codes from anything else as I only put batteries in the scanner before using it. Additionally the codes are ODB2 codes rather than OBD1 codes. I'm off to bed now.

There you have it then, either a wire is broken between the port and the computer, the light is burned out the computer is not powered up or the computer has failed.

I am unable to speak on the phone, we can continue here if you wish.

Do you have a voltmeter?

Does the check engine light come on with nothing in the port and you turn the key on?

Does the engine run?

Customer: replied 8 months ago.
I am unable to speak on the phone, we can continue here if you wish. Okay. I just thought we could make this faster. However the info is more important than speed.Do you have a voltmeter? Yes, I said that earlier as I used it to make sure the batteries were at the 1.5 v level.Does the check engine light come on with nothing in the port and you turn the key on? YesDoes the engine run? Yes. The car drives and sometimes (maybe 1 in 20 starts) stumbles when starting from rest.
Although I cannot get the paper clips to flash anything, and the scanner will not show DTC codes when connected to the port, when I came inside and the scanner was not connected to the car, DTC codes P0202 and P2149 appeared. Both codes are consistent with the car stumbling and are related to an electrical problem related to cylinder 2 and injection group B.

OK, then you are going to have to check at the computer itself and ground the diagnostic wire, I will post a diagram of the location with the wire color.

For now ignore the scanner, it is in the way of the diagnosis, the paperclip is more direct.

You said you "repositioned" the paperclip. Did you probe any other pin sockets besides the A and B?

Measure the voltage between A and B, with key on you should see 3 - 6 volts with a digital meter. Do not be confused about that voltage, it is for diagnostic purposes only and does not power anything.;

Customer: replied 8 months ago.
You said you "repositioned" the paperclip. Did you probe any other pin sockets besides the A and B? No. Repositioned means I tried to push it in futher into the A&B holes, but I never changed holes. Do you think what the scanner has said is bogus?


I don't know what the scanner is doing, I don't use those. I do knopw that you need to be able to flash codes and you are not able to do that so lets find out why.

On the computer up behind the right side of the dash is a 32 pin yellow orange connector. You need to slide a straight pin along the white/black stripe wire to make contact inside the connector and run a wire to the pin and ground it. Turn the key on and see what the CEL does (check engine light). First measure for voltage between the A and B and if no voltage measure form the B to a clean ground.

Let me know what you find and how I can help


Click here for diagram

You are looking for pin D6, the view is the front of the connector and you are looking at the back (wire) side. Double check that by looking for the white/black stripe wire in the D6 slot. If you have the 3 - 6 volts at the diagnostic port you do not need to check at the computer.

Let me know what you find


Customer: replied 8 months ago.
It has been heap big cold and I will have to wait until it warms up and I can stand the temperature and not freeze my fingers off.

Thanks for letting me know, I will be here when you have a chance to check it out so let me know what you find so we can get to the bottom of this


Customer: replied 8 months ago.
I waited until it warned up and tried the paper clip again. It worked!! It produced the dreaded code 41 and I found the magnet was missing in the cam area. I changed the timing chain, water pump, timing chain tensioner, and cam sensor, along with getting another interrupter (magnet); now all is well. While at it I also found the oil pan gasket was hanging out the oil pan and so the gasket was replaced also. I only have to pop in another thermostat because I am getting low heat on a brand new blend of antifreeze that was done while the engine was apart with the cover off. So,I'm really good to go now and will be totally good when I change the thermostat later this week. Thank you so very much for your help!!.

Good! don't know what is up with the scanner but at least you know the vehicle is operating normally.

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