Just curious. Right now, I don't have my vss hooked up (my cluster is cable driven and the vss on the transfer case is electrical). My truck seems to run perfect and the only codes I have are from the automatic transmission (I have a auto ecu but my swap is 5spd).

So is there any reason for the ecu to see the vehicle speed?

 

I havent been able to figure out my speed sensor on my 3.4 swap either. Been driving it for months without a speedo and the only thing that happens is I get a VSS code. No other problems I see though. It might matter if it was an auto, I'm not sure, but my 5spd works just fine.

 

thanks for the response. I think alls I need is a cable driven vss, plug in speedo cable, and I should have an operating speedometer. But as of now, I have nothing and the ecu sees nothing. but like you said, all seems well and so far, no codes have been thrown. i am running an auto ecu with a 5 spd trans, and everything runs well.

thanks for the response again!

 

I just asked this question at ORS since I have a cable driven speedo. I was told in my case (88 22RE) that the ECU will get the speed signal from the comb meter and my cable drives the speedo like it normally would.

 

You can feed the VSS signal from the instrument cluster back to ECU. It works for me. The OBDII reader can see the speed also.

 

This is exactly right. All the wires for it will be right there at the body harness plugs.

 

got my cable driven vss in the mail today. took out the electronic one that was located in the transfer case and swapped it out. Now my speedometer and odometer works perfect, but I have yet to hook up the vss wire from the cluster to the ecu. as far as I know, the truck runs perfect mechanically and electronically without the ecu reading the vehicle speed.

again I wanted to ask, why does the ecu need to "know" how fast the vehicle is going?

 

It could be for optimized economy or power. But if its an auto ecu its needed for proper gear shifting.

 

its an auto ecu, but 5 speed truck. I tried emailing ORS to see what they have to say. Haven't heard back from them yet. thanks!

 

Honestly, I haven't noticed a difference from before when the speed sensor wasn't working to after when it was replaced.......

 

thanks! i also agree with you as the truck seems to run flawless. I think I will leave it at that, and just leave it alone.