2000 chevy truck 5.3 Vortec 2wd. Tried to read codes and my tool wouldn't connect. Radio and lighter fuses good. Checked for ground and that was good. Can anyone give me some common conditions you've heard of causing the OBD connector to not have power. I did not check for signal or anything else when I figured out it wasn't getting power. Also could not find any blown fuse at all in both fuse block locations. Thank you in advance!!

You have 3 fuse blocks, not 2. Check the "AUX PWR" fuse in the underhood fuse block. It is near the center of the fuse block. Are there any indications of issues with the ignition switch? Sometimes a faulty ignition switch can affect power to the OBD port.

Hey thanks Brother for your reply. Aux. fuse is good. All fuses are good unless I missed checking one mistakenly. No problem with the ignition switch as far as I know. I will ask him if he'* had any issues. If the connector don't have power, will the check engine light still be functional? Yesterday before I started a intake gasket replacement for a customer, there were no SES light on. After I finished he came to get his truck and when he started it up the SES light was flashing and as he drove away I could tell the truck had a miss on at least one cylider. I called and told him to park it until today when he brings it back so I can see if the OBD connector will have power and connect to my scanner.

Sometimes they are fed via the CIG fuse.

Correct. It is the fuse in the fuse box underneath the hood. It is marked CIG LTR 15A

When standing at the drivers front fender, looking at the fuse box, the fuse will be located near the right edge of the fuse box........4th fuse up. It requires a 15A fuse.

This fuse circuit supplies power to the OBD connector and the cigarette lighter.
NOTE: The other "cigarette lighter" sockets are auxilary power ports for electronic devices. The difference being: Those auxilary ports have constant power where as the cigarette lighter only has power while the ignition switch is turned on.

I really appreciate y'alls replies. He brought the truck back to me and within 10 mins I found an injector wire that was off the injector. I fixed that and his SES light went off and has not lit up since. I'ma hero. lol As far as the OBD connector, still no power and every fuse is good. Then he told me his cig lighter or aux port blows a fuse every time he plugs in to it. I told him to find that short and maybe problem solved... Thanks again guys

The aux ports are not associated with the OBD connector.

Look at some diagrams of the OBD pinout. You can cut the #16 pin wire and "hotwire" some power to it (with ignition switch power). The #16 pin wire will now supply power to you OBD scanner device.

Be safe, install a 15A inline fuse with the jumper wire.

Agree with the guys....the CIGAR fuse(15a) provides power to term 16 of OBDII connector....have you checked the fuse with a test light?

1.8TTony has given you an option for the problem...

For clarification, according to the owner'* manual for a 2000 Silverado the cigar lighter fuse is labeled "AUX PWR" in the underhood fuse panel. For those who are arguing auxiliary power has nothing to do with the cigar lighter, the automotive term for the power outlet you plug the cigar lighter in is an APO, or, auxiliary power outlet. APO = auxiliary power outlet = cigar lighter outlet.

looked up schematic for 1500(he doesn't give model).......circuit comes from fuse labeled "CIGAR"....