Last 3 Gauges

[ChevyMan90]

I did a LQ9/4L60E swap in my 1999 C1500 OBS. I have my water temp, oil pressure and voltmeter gauges working. I just need my speedometer, tach and fuel gauge to work now. I have downloaded and printed all the wiring diagrams/connector end views from lt1swap.com and some from All Data. Im using a new standalone wiring harness and it has a lead for tachometer signal output and a lead for the vehicle speed signal. Where should I connect the wires coming from my new LS harness to the existing wires to get power to my gauges? I see several Pins on the 4 VCM Connectors that say Vehicle Speed Output. Also I have a diagram for the C100 connector that goes into the firewall on the drivers side. Does the tach get its signal from here? Looks like it will be a white wire, either connector B2 or E8? Lastly theres the fuel gauge. If anyone can give me some help on where I should start I would greatly appreciate it. Thanks!

[ChevyMan90]

Well I got my speedometer working. 2 more to go.. Any help on the tach and fuel gauge? Thanks

[crzy8mnky]

How much of your old harness have you removed? The tach signal comes from a white wire on a three wire plug that goes into the coil. The fuel gauge signal is a purple wire that comes from the computer.

[gagliano7]

The tach wire is the white one that was hooked to your distributor. You may have to make changes in the tune for the tach to work.

[ChevyMan90]

My entire old harness is still in my truck, along with my new harness working all of the engine/trans functions. I haven't removed or cut any old wires yet. Once I get these last 2 gauges working I can start getting rid of wires I don't need and clean up the engine bay. I have not had a chance to work on the tach and fuel gauge but today I will be looking into it. Can anyone confirm where the tach signal comes from on a 96+ Vortec motor? The coil or the distributor? Thanks for helping be narrow it down.

[crzy8mnky]

If you connect the white wires of the coil and the ignition module and then pull the tach signal wire from the old engine connector into the new connector you will have a tach signal. IIRC the only plug going into the distributor on the Vortec 5.7 is the camshaft position sensor. On the TBIs the ignition module is under the distributor cap, however on the Vortecs its on the passenger side of the intake manifold.