I get lost with the VSS.
I have a new gearbox TKO-600 that fits a GM engine.
I am putting a wiring harness from S10Wildside (EFI Connection).
It is a SD with a 730 ECM.

According to my information the gearbox has a reluctor with 12 teeth’s.
This will generate with my rear end and tire size a 31100 pulse per mile.
The EPROM ask for a 4000 pulse per mile (You can also adjust to 2000)
I see also a that there is a section at the EPROM that says “VSS Instrument Panel Pulse Divisor” it is set to “0” at the AXCN bin file.

Is there where I can adjust the amount of pulses?

Have some one solve this issue with the TKO-600 VSS?

Best regards,
Cobra289

 

You can probably read the signal in direct so long as you use a buffer box. You then set the constants in the ECM to the correct values. The only issue may be how the ECM reads it in. If it uses the period, then youll have to scale down the # of pulses per mile.

 

Probably something like a dakota digital speedo interface could be used, assuming it can interface with the pickup in the TKO.

 

Hi Dimented24x7,

I have a special project running here. It is a Shelby Cobra replica with a running gear of GM.
I am in the middle of the change, engine 350 with HSR and the TKO-600 gearbox.

It doesn’t have the “Buffer” at the instrument panel. So tapping at the buffer is impossible.

I thought that this would be an standard solution due to that lots of people have a TKO with the 12 pulse per RPM sensor, but it seams to be that there is not so easy or so frequent swap.

After searching for solutions with out the Dakota Digital I found these thread, which looks very promising.

I have also a stand alone VSS that gives 2000 ppm that can be hock-up to the cable driven output of the gearbox.
But due to that the Cobra’s have so little space I should change something at the tunnel.

My Speedo is driven by cable so there is not a problem with it.
As you know the TKO has a mechanical speedo and a electronic VSS

Here is the link of the thread.
https://www.thirdgen.org/forums/diy-...libration.html

Thanks,
Cobra289

 

I would imagine that the dakota box would be the easiest way to go, assuming that it can interface with the pickup on the TKO. You could then scale it down and feed it into the VSS. It wouldnt be exactly 2000 or 4000 ppm, but it would be in a range that the hardware could read it in with some degree of precision. The signal from the TKO would need to be scaled down by at least a factor of 4 or so. You would then adjust the scalar for the VSS in the ECM so it gives the correct MPH. Some math involved, and requires extra hardware.

The other solution might be to use one of the earlier pre 89 GM speedo's with the integral VSS, if it can be made to fit your vehicle.. The VSS is right on the back of the speedo, so theres no need for any external hardware. The speedo cable drives the VSS.

 

As another possibility, The B & M TCC controller has a cable driven pulser that is 2 PPR instead of the 4 but would give 2000 PPM.
Just goes inline. Might be available as a replacement part from B & M.
Just a thought.

... You've got mail

 

With a 730 ECM you would set it up to use a magnetic speed sensor in the code and wire the sensor to the magnetic sensor pins on the 730 ECM. Then the magnetic pulse divide needs to be set for the ECM to see the correct road speed.

The speedo is another matter. The 730 only offers a few divide values in the hardware which is controlled by the code. You may get lucky and your PPM with one of the dividers comes out close but not right on. You really need a divider box to get the speedo the correct number of pulses. Either a small counter chip ckt or a buffer divider box out of a 90's pick-up or the like.

 

Thanks guys, it becomes a bit clear and I got some possible solutions with external equipment.

I have check with the TKO sensor and if I divide by 8 it would be in the range of the 4000 ppm.
That means that I need to set bit B7, B6, B5 so that it would have a division by 8.
But that divisor is only used to inform the speedo, if I am right!

My speedo is cable driven so that is solved. It is the ECM that needs to have the correct 4000 ppm

In the case that these ‘VSS Instrument Panel Pulse Divisor’ will not work for me, I like is the 4000 ppm sensor from V-8 Vehicle Speed Sensors (VSS), Speedometers, V8 Conversions

Thanks for the cooperation.
Regards,
Cobra289