1999 Chevy Blazer service engine soon

Hello, pin 4 is chassis ground for the scan-tool, pin 16 is power for the scan-tool. If those two pins check out???? Does the mil come on, key on, no crank? I can talk to you about the basics, after that???

I am not getting any power to the diagnostic plug.

if your not getting any voltage to pin 16, check the fuse and circuit for the cigar lighter, fuse 2-- 15 amp.

I checked the fuse and found that it was blown. I replaced the fuse and it blew right away. What now?

Remove the cigar lighter from the socket. Check again, you can use a testlite across the fuse terminals instead of blowing all your fuses. If the lite comes on, the circuit is still grounded, somewhere.

I removed the cigar lighter, and used my digital voltmeter on a different set of fuse terminals. It checked out at 12 volts. I then checked the # 2 fuse terminals and I was getting readings all over the place, 300 to 180 to 65 and every number in between. What's next?

If you were using the voltage setting on the meter, I don't know how you got those numbers on a 12 volt system? I think you got a short on that circuit somewhere if the lighter element is ok.

I was having the same problem on my blazer as soon as I disconnected the cigarette light from the wire harness it stopped blowing fuses and read my scan tool.