get a scantool and/or a datalogging cable especially if you are planning on keeping the vehicle. reading the data stream is mandatory IMO. I think you need to read the manual for your aftermarket speedometer and figure out how to calibrate it. Have you tried contacting them for tech support?
EDIT: chances are if the torque converter is locking up, the ECM is getting a speed signal. this would be a quick and dirty way to test it.
disregard
Last edited by tayto; 10-26-2022 at 03:42 AM.
@AzDon,
Have you figured this issue out yet?
I came to the conclusion that nobody else has ever had to deal with this issue, so maybe I'm the guy that doesn't understand..... My mind is stuck in analog, so what I'm going to do is get a GM police car VSS unit from JTR Stealth that has provisions for a speedometer cable where I can add the intellitronix VSS that came with the cluster....Meanwhile, I'm using my eyephone as a speedometer to keep me outta trouble...
Ok, let me see if I can help you out here.Originally Posted by AzDon
1. Are you using the intellitronix speed sender that goes into the transmission?
2. What model/year transmission are you using?
I converted my analog cluster to a digital cluster that required 2000ppm, (not clicks), signal to work. In addition to that, ANY DRAC can be used, but must be modified slightly for gearing and wheel size.
I had intended to use the GM factory VSS and DRAC module, not realizing that (according to the posted article) the drac converts the signal it receives to negative clicks to ground and depends on the speedometer to provide the electricity......The intellitronix panel expects the vss/drac to provide a positive signal......For about two minutes I considered using a relay to flip the signal to positive before realizing that relays aren't designed to pass thousands of clicks....
It's possible that the Drac simply doesn't work, although the factory speedo in the donor wagon worked fine...
Assuming that it's okay and the posted article explains why my aftermarket won't work, I think it's probably best to leave the factory Vss and DRAC in place and simply add the intellitronix gear-driven VSS in tandem with the stock one using a JTR Stealth sourced unit that was original equipment for Caprice cop cars that needed the cable drive for their timing equipment....
I'm guessing that the reason this issue never comes up is because either 1) I'm crazy or 2) Maybe it's unusual for for folks restoring/building old nova or vans to try to use the GM VSS/DRAC to run an aftermarket speedometer....
Right now, I'm elbows-deep in adding more caster to my axle flip and my cell phone GPS can handle being a speedometer for now.....
You mean negative pulses.
I'll rig up a drac with a signal generator and see what the signal is converted to, but I believe it is positive voltage going to zero reference output. An inverter of sorts can be made cheaply with few parts.
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