Winchested

What would be the proper way of installing the VSS (Dakota digital 8k ppm) pass thru with a speedo ratio adapter box?

Tcase output--> VSS--> Ratio Box

or

Tcase output--> Ratio Box--> VSS

This will be on a 5.3/NV4500 w/ doubler/ dodge NP205

Originally my Dana 300 Output with 35's and 4.88 gears was perfect with stock output and with 5.38s and 40's its pretty much spot on too, but I'm assuming going to the new tcase may change that ratio. I likely wouldn't know how far off it is until I was able to Match it to GPS speed when doing 50- 60 Mph.

Thanks for any insight.

G Atsma

The "High" speed ratio should still be 1:1, so I fail to see the issue with changing transfer boxes

Winchested

This would be correct if the transfer case was being installed with stock sized tires and gears? But most all transfercases have different tooth pinions to get the correct ratio for gear/ tire. Hence the ratio box rather than changing pinions as most of the pinions are long out of production due to computer reluctor VSS now.

Just trying to wrap my head around it.

garys 68

iTrader: (1)

If you're not running anything off the VSS other than an ecu signal, it doesnt matter. The function of a vss is primarily to avoid stalling with a manual trans.

Winchested

I do want to eventually be able to use cruise control with a dash mounted 4 button deal (Dakota digital or the like) that is wired into the TAC module.

garys 68

iTrader: (1)

The pulse rate of the dakota digital VSS is not high enough to work with the stock ecu. I had to use the reverse gear (39 tooth) on my T10 to get my DBW cruise control to work.

Winchested

Interesting Gary thanks.

I did find this over at HPtuners

https://forum.hptuners.com/showthrea...l-8K-Pulse-VSS

Saying there is the possibility of changing the signal in the ECM.

wave1957

Since you are using Dakota Digital parts (VSS, cruise), have you tried asking them how to make it all work?

Winchested

Yes they suggested using their SGI-100BT which just amplifies the Signals for tach and speedo ref. But it's another $150 and adds more wiring mess into the mix.

This is why I was hoping to be able to just have the ECM adjusted to read the 8k ppm signal. Which seems doable I just need to find the right tuner.

I'm starting to think you'd want to run the VSS after the ratio box so the ECM is seeing actual speed at the 8k ppm.

Watching Brendans (LT1Swap) Vids on Youtube The cruise uses a 4k ppm Signal from the ECM. So the ECM must convert the OE 40k ppm signal.

garys 68

iTrader: (1)

You can adjust the ecu to read the correct speed, it's just the rate is not high enough for the dbw cruise control to work correctly. It wnt from idle to wide open every second. ECU read correctly, but doubt the ecu was reading a stable signal for cruise.

Winchested

You're saying this was your experience?

I might just abandon the cruise option for now. The wiring is there. Can buy the Dakota digital box later on ,the 4 wires are all set up from the TAC module connector so it would just be tying in the clutch disengage, brake and brake switch.

I assume with a manual I don't need the TCC wire I added a pin for the Clutch switch on pin 35. Don't want to run the clutch engaged for start switch, I'll just get that code deleted in the tune.

garys 68

iTrader: (1)

Yes, tried it with the DD VSS, no luck even with the correct speed tune on the ecu. Used the 39 tooth reverse gear in my T10 as a reluctor, worked fine. Oh yaeh, I did have to retune for the correct speed since the ecu thought I was going 140mph at 35 mph and limited my top speed, lol.