hi, i am trying to install the avic-z1 on my 2002 avalanche but im having trouble finding the speed detection circuit lead that comes from the fuel injection computer for the navigation system. Would it be one of the wires on the harnest that connects to the speedometer? if so does anybody know what color it would be. please help.

Thanks,
Danny

Ok if your stock radio had the speed control volume, you might be able to find it right at the radio harness. It would be the same color as listed below.

Speed Sense dk.green/white ECM
Notes: The ECM (Engine Control Module) is located near the battery, down low, between the fender and the fan under the black plastic cover. On the 4.3L, the VSS wire is in pin 3 in the connector labeled black. On the 4.8L, 5.3L, and 6.0L, the VSS wire is located in pin 50 of the red connector.

i found a drk green cable in the harnest connected to the speedometer. is it possible that this cable would be the vss cable?

There will be two or more green/white wires in the speedo harness. One is the VSS, and you can use this. Use a multimeter to test for the wire that pulses while the truck is moving. Have a buddy help you so you don't crash into a bus full of nuns. The wire will pulse even if the cluster is removed, so you dont get it caught in the steering wheel, and, again, the nuns.

so to check for a pulse i should hook uo the negative side of the volt meter to the ground and the positine to the possible vss cable? what setting do i use on my volt meter ac or dc?

AC voltage.

You can detect the pulses on either setting, because the wire pulses to ground. So, if you are using a DC meter, connect one lead to +12V, use the other lead to hunt for your VSS.

There is an appropriate VSS wire in the radio harness. It's dark green and may have a white stripe. I thought I remembered it looking bluish on mine. If you have a harness adapter, it's on the side with no wires. There are 2 connectors on that side, a 6-pin and 4-pin. The VSS wire is the one on the inside of the 6-pin side.