electronic speedo?

[draggin86]

So i am planting my L31 vortec 350 in my c10 with my 4L60E transmission. So i have been told if you use the new 90-91 blazer or suburban gauge cluster you can use input from the transmission.. my question is how to i hook up the input to the cluster.


Thanks
Billy

[Jonboy]

From what I understand, the electric speedometer uses three inputs. There is a 12+, ground, and a signal from the PCM. All three of these will plug into the rear of the cluster, and just need to be connected accordingly. At least this is how I understand it.

[78-5.3]

there will be one one coming from the PCM it will hook up too the speedometer

[draggin86]

Copy that guys thanks for the insight i have my speedo coming.. im just torn weather i should mod the OEM harness or to do a standalone.. the standalone seem to be pretty pricey ranging from $400-700 not including a tune.. waitforme said they would tune for 85 bucks so this is where im at right now.. the painter has the truck so i have some time.

[78-5.3]

Originally Posted by draggin86

Copy that guys thanks for the insight i have my speedo coming.. im just torn weather i should mod the OEM harness or to do a standalone.. the standalone seem to be pretty pricey ranging from $400-700 not including a tune.. waitforme said they would tune for 85 bucks so this is where im at right now.. the painter has the truck so i have some time.

try brendan at lt1swap.com

[draggin86]

Originally Posted by 78-5.3

try brendan at lt1swap.com

I just emailed him see what he says

[sailed2japan]

If you decide to mod your existing harness I suggest getting the original schematic and drawing out where you are going to tie inyour new harness. A little extra time in the planning will save alot of time in the "oh, $h!t"

[Jonboy]

Originally Posted by sailed2japan

If you decide to mod your existing harness I suggest getting the original schematic and drawing out where you are going to tie inyour new harness. A little extra time in the planning will save alot of time in the "oh, $h!t"

x2. Whoever swapped the engine in mine skipped this step. It would have made life quite a bit easier, but I am looking forward to sorting it out.

I went ahead and picked up an electric cluster too. Hopefully I can get the gauges to work now.

[68 TT]

I don't know what kind of signal the L31 vortec PCM is looking for from the VSS but on the LT1 & TPI swaps I have done they both worked perfectly using a dual output VSS from a 93 vintage Caprice cop car. VSS-231 at NAPA if I remember right.

It has both the mechanical speedo output and the VSS output on it so I was able to keep the stock cable driven speedometer but still give the ECM/PCM what it needed too. The mechanical side was to drive a speedo cable driven radar gun. I know it is the wrong type of signal for a TBI swap but since the L31 is port EFI I figured it might work with it too.

The same VSS unit fits into a 4L60, 700R4 and a T-400.

[Jonboy]

Using that VSS, what type of drive gear is used? I looked on the JTR website, and got more confused. It looks like you have to add another gear to the output shaft of the trans to get it to work. I also looked at the S&P modified tailshaft, but figured I could spend $450 a better way.

[68 TT]

Originally Posted by Jonboy

Using that VSS, what type of drive gear is used? I looked on the JTR website, and got more confused. It looks like you have to add another gear to the output shaft of the trans to get it to work. I also looked at the S&P modified tailshaft, but figured I could spend $450 a better way.

Depends on the year of the trans. The newest one I used the dual output VSS on with was a 93 4L60 that came behind my LT1 so it still had the plastic speedo drive gears not the newer trigger wheel ring design. Most likely the switch happened with the change to the 4L60E so it won't work with what you have, sorry for the confusion.

You could always switch to a non-electronic 4L60 / 700R4 to save a pile of cash up front but the tuning features of the electronic trans are pretty cool and I'm not sure how the PCM would interface with the non-electronic trans to control TCC functions or how you would get the TV cable to connect to the vortec throttle body.

Sounds like you are much better off using the electronic speedo and keeping the 4L60E.

[78-5.3]

IF its it has 4l60e then isnt the ecm edited for what the rear end ratio and what tires size thats what happen to me they want to know what rear end i had and tire sizes

[68 TT]

Originally Posted by 78-5.3

IF its it has 4l60e then isnt the ecm edited for what the rear end ratio and what tires size thats what happen to me they want to know what rear end i had and tire sizes

You are correct. With the 4L60E you change settings in the programming to account for gearing and tire diameter.

[draggin86]

Hey guys i do have the pin put of my truck i was thinking of getting the GM shop manual for the motor i pretty much have it figured out from what i have found online and a few other places. as for the transmission it is the newer electric speedo tranny just like the ones that would come in a 5.3L i dont feel like wasting money on converting the tail shaft and calibrating the gear sets to get it right when i change the wheels when it could just be tuned.

Thanks for the help guys!