What pulse does it need? The ECM in your truck gets 2000 pulses per mile.
Your truck has a DRAC, I *believe* it's located under the dash near the ashtray. Whitish square plastic box with a few wires going to it.
The VSS wires coming off the transfercase are 40 pulse per revolution, so I doubt that's what it wants, nor would I cut those.
As a matter of fact, I wouldn't splice into any of them.
http://coloradok5.com/forums/showthread.php?t=124012&highlight=drac There are other posts, this one is mine. The DRAC has a bunch of outputs as you can see from the pictures, so you don't need to splice, you can de-pin one of the connectors, and with the right pigtail from the wrecking yard, you can simply add the wire you need. Assuming the GPS unit shows MPH calculated from the VSS, you would want to make sure the signal is right. 4000PPM will obviously double your speed, and those figures I link to are only correct for certain years, from what I found not all have the same PPM in the same location.
Or, you can splice the wire that goes to the A10 pin on the ECM connector. I know most people will take the easy route, that's the easy route. I just don't like splices if I don't need them. They never work out as well as a new wire.
