1998 Tahoe Security Light

if it's flashing while starting, then you have a passlock problem.  do you have a remote starter or ever messed with passlock in anyway?

It's a hit or miss on the flashing...and yes it does have remote start. I never touched it except replacing the key fob. i took the cuircut board from the old one and set it in the new fob casing. The old one was cracked.Mike Jones

Mike's Mobile DJ Service

It is possible that the problem is due to the Passlock II interface used by your remote starter. Some types of interfaces are intrusive and require the yellow Passlock signal wire to be cut and the bypass installed inline. Many of this type of interface use DIP switches to set the correct resistance on the Passlock signal wire. They are prone to fail. I would suggest that you find the bypass and temporarily remove it to see if the problem goes away. You will need to rejoin the wires if any were cut. Make sure you do it at the point where the tap into the factory wires to rule out bad connections. Solder the wire back together for a good connection. If the problem goes away you know it was the bypass, and you can then replace it with a newer non-intrusive style bypass that works on the vehicle's class II data bus. If the problem doesn't go away then you may want to take the truck to a GM dealer to have them repair the Passlock system. Ruling out the remote starter is your best bet, as the dealer will blame it for the problem whether or not it actually is the problem. This way they will only charge you for the Passlock repair and not their opinion on remote starters.sparky