Ignition timing bypass mode

I have a 1992 GMC Sierra with a 5.7 and manual trans. Just had the heads redone. Running fine ,but I would like to check the timing with timing lite. The only trhing is I can't figure out where the wire is that you are supposed to disconnect to get into the bypass mode. I know that it is a tan with black stripe single wire but I can't seem to find it. Could someone please tell me where to find this wire? This is driving me nuts!!!:screwy:

On my 90, the bypass wire is under the black cover for the power distribution block on the passenger side of the firewall.

//2000CAYukon

Thanks for the reply. I finally found it. It was in the junction block on passenger side firewall as you said. Timing was way off, unplugged connector, set timing. Runs like new truck. Thanks.