BAN HAMMER

So my check engine light is on in my 2000 Silverado. When I plug in the scanner, however, it says that it needs to be connected to the vehicle. Is there a fuse for the port somewhere or does it run off a fuse for something else? My cigarette lighter fuse was blown so i replaced that, I havent tried the scanner since that yet though. Any help would be appreciated.

Fabrik8

It may be off of the same accessory circuit, yes. Depends on the vehicle. Find an OBD2 pinout for your type of vehicle and check to see if there is power on the relevant pins.

BAN HAMMER

Oh shit here is the other thing I forgot to mention.

When I plug the scanner in with the truck already running, after its been plugged in for about 30 seconds my SECURITY light comes on and stays on until i turn the truck off and re-start it.

WTF???

Fabrik8

Make sure you're using the right protocol... There are 5 or 6 different protocols so you need to use the right one for your vehicle. GM only uses one of 2 protocols, most everything is CAN based now but back in 2000 some vehicles were still the other protocol. That may explain not being able to connect to the vehicle, and the security light coming on. Could be completely unrelated, but it's worth checking into.

The standard OBD2 connector is used with all of the different protocols, so my WRX that uses the ISO9141 protocol uses the same connector that your Silverado uses for CAN or whatever GM used back then on that truck (J1850 probably?).

Fabrik8

Yep, your truck should use J1850 VPW protocol if that helps any.

BAN HAMMER

Thanks, I'll check it out and see what the scanner is set up for.

BAN HAMMER

Cigarette lighter fuse fixed it
now its giving me a random cylinder misfire code

Fabrik8

Well, the port works. That's a start.

BAN HAMMER

lol, i guess.

its giving me code p0300, p0422.

So hwo would i go about fixing the 300 code (missfire)?

Fabrik8

The easiest thing to do is to change the plugs and check and/or replace the plug wires. Where the problem could be depends on whether the problem is a misfire randomly on all cylinders or just on one cylinder. If it's one cylinder, the list of usual suspects is pretty short.