7730 ecm 40 tooth tone ring

[misterpat]

Hi all!

Finally getting to the point of hooking all my fuel injection up. I started a previous thread on here about feeding a Jeep speedometer and the tpi ecm with the same sender.

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?4227-1992-Jeep-Wrangler-with-350TPI-700R4-VSS-Options

I decided to go a different route and do a full custom dash. So I can get a speedometer that will work with whatever I got.

Now my question about feeding the ecm with the vss i got.

With a 37" tire and 5.38 gears, my driveshaft will spin 3055.84 times a mile. Which will make 122233.6 pulses per mile.

Looking through the ANJF bin in TunerPro RT in the scalars section on the bottom is Vehicle Speed Sensor. In there I can set the ppm to 115200 which is close.

But will the ecm be able to use this type of input? I've been googling it, but no yes or no answer.

11746

[1project2many]

What type of pulses are being supplied by the VSS? A/C or D/C? The 115200 value will work with an A/C sensor. The rules change with a D/C signal.

[misterpat]

I think it is A/C. The sender I have is a DORMAN 917-616 which was used in many GM vehicles from 88 through 05 it looks according to rockauto's site.

[1project2many]

Yes, that's A/C.

[misterpat]

Now I'm wondering. If this will work, but only be close, not right. Would I just be better off running a drac?

EDIT:

Can I even use a drac with the 7730 ecm? It outputs square wave, correct?

[RobertISaar]

you can feed a 7730 a square wave VSS signal, just need to move the VSS input wire to a different pin and change a flag. AFAIK, every mask run on the 7730 supports the "optical" VSS input.

[misterpat]

Sounds easy enough. Anyone know what pin is for the square wave input?

So I got this straight.

1. Repin the VSS input to ??
2. Re-jumper the drac for my proper multiplier.
3. Change my bin to use the square wave input "optical" at 4000ppm.

Correct?

Thanks!

[1project2many]

Yes. Pin C6. Set up the DRAC to produce 2000 pulse per mile. Clear the "magnetic VSS present" bit 6 @ 0x0018. The speed sensor pulse per mile divider will no longer be used.

[misterpat]

Awesome, Thanks! So once that "magnetic VSS present" is cleared, the "Road Speed Constant" at 0x15 is irrelevant? Or does it need to be set to 2000ppm as done here:

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?4713-How-to-Installing-a-DRAC-on-a-7730-ECM

[1project2many]

The RSS affects the signal sent from the ecm to the instrument cluster.