Tach wires LS Conversion using the stock tach DIAGRAM

[Shes Mad]

I finished wiring up my factory tach today with the Dakota digital SGI-8E module. I couldn't find a definitive diagram in the search, so I posted this up. Easier than looking through a long build thread

I decided the easiest way would be to splice into the wires on the vehicle side of the instrument cluster tach plug. Everything you need is there, except the signal in, which would come from your PCM. Wiring to the vehicle side of the plug makes it so you can remove your cluster without doing anything but disconnecting the normal factory plug in's. Only needed minor adjustment to the gauge, which the instructions detail pretty well. I checked it at 500 up to 4000 in 500 increments, and it was pretty accurate. Hope this helps some people out

 

[JohnCapoccia]

Very nice. I'm sure this will help the next guy doing a Vortec. I had to fumble through, especially dialing in the settings to get the ouput accurate. This would have been helpful!

 

[Matt Crandall]

I was very excited when I saw your diagram. I am doing a conversion on a 91 fj80 to LS. I have the Dakota adapter. I can not find this plug that you show in your drawing. Any assistance....
thanks

 

[Shes Mad]

I was very excited when I saw your diagram. I am doing a conversion on a 91 fj80 to LS. I have the Dakota adapter. I can not find this plug that you show in your drawing. Any assistance....
thanks

This diagram is for a 60 series. However, the only thing you really need to find is which wire is the tach signal for your truck and tap into that with your output from the dakota digital.

Then just power, ground from anywhere. VSS from your swap harness to the dakota digital box

 

[BHillteq]

I finished wiring up my factory tach today with the Dakota digital SGI-8E module. I couldn't find a definitive diagram in the search, so I posted this up. Easier than looking through a long build thread

I decided the easiest way would be to splice into the wires on the vehicle side of the instrument cluster tach plug. Everything you need is there, except the signal in, which would come from your PCM. Wiring to the vehicle side of the plug makes it so you can remove your cluster without doing anything but disconnecting the normal factory plug in's. Only needed minor adjustment to the gauge, which the instructions detail pretty well. I checked it at 500 up to 4000 in 500 increments, and it was pretty accurate. Hope this helps some people out

View attachment 1441049

Dang this is EXTREMELY helpful, thanks for sharing this! When you say you spliced in, did you just tap into the wire? Using something like this?

 

[Seth S]

Dang this is EXTREMELY helpful, thanks for sharing this! When you say you spliced in, did you just tap into the wire? Using something like this?
View attachment 2435611

Strike this idea from your thought process. These little blue things were designed by the devil and are the very definition of lazy. These things only lead to problems down the road. Highlight suggest you take the time to do the connections properly....either by cutting wires and doing new connectors or adding a junction...Just don't use Crimp Locks.

 

[BHillteq]

Strike this idea from your thought process. These little blue things were designed by the devil and are the very definition of lazy. These things only lead to problems down the road. Highlight suggest you take the time to do the connections properly....either by cutting wires and doing new connectors or adding a junction...Just don't use Crimp Locks.

My thoughts exactly. Haha, thank you! I'll splice it in much cleaner.

 

[Shes Mad]

Yes--just tapped into the wire.

For some reason, my tack would not work with the small plug on my AC amp connected. Might me something I did, but if the small wire is connected on the AC amp, my tach would not work, and the AC amp relay was constantly ticking. Everything works fine with it disconnected

 

[BHillteq]

Yes--just tapped into the wire.

For some reason, my tack would not work with the small plug on my AC amp connected. Might me something I did, but if the small wire is connected on the AC amp, my tach would not work, and the AC amp relay was constantly ticking. Everything works fine with it disconnected

Perfect. Thanks for the response!

I have a TBI 350, rather than an LS, and currently the AC is non operable. So we'll see if I run into that.

 

[Slow85]

I finished wiring up my factory tach today with the Dakota digital SGI-8E module. I couldn't find a definitive diagram in the search, so I posted this up. Easier than looking through a long build thread

I decided the easiest way would be to splice into the wires on the vehicle side of the instrument cluster tach plug. Everything you need is there, except the signal in, which would come from your PCM. Wiring to the vehicle side of the plug makes it so you can remove your cluster without doing anything but disconnecting the normal factory plug in's. Only needed minor adjustment to the gauge, which the instructions detail pretty well. I checked it at 500 up to 4000 in 500 increments, and it was pretty accurate. Hope this helps some people out

View attachment 1441049

Man last thing on my list is Tac and A/C. This box does not seem to be available anywhere. But it looks like this module (SGI-100BT) is the replacement for: DSL-1, DSL-1E, SGI-5E, SGI-8E, DSL-2E).