Need help retrofitting DRAC module!

[mrjeffyt]

Electric speedo not responding!

I have searched and searched, can't find help with getting the speedo to work! I've wired up module, repinned my cluster, everything works except speedo! I was wondering how to find out if the speed output from DRAC is right. Trying to troubleshoot before assuming bad parts and spending money to still have the same problem! I've tested the speed sensor, AC voltage climbs with acceleration.

The speedo unit has power, when connected, the needle drops to "0" and holds there, I don't believe odometer motor is working either.

Thanks a lot for any insight you guys can pass along!

 

[foamypirate]

I have searched and searched, can't find help with getting the speedo to work! I've wired up module, repinned my cluster, everything works except speedo! I was wondering how to find out if the speed output from DRAC is right. Trying to troubleshoot before assuming bad parts and spending money to still have the same problem! I've tested the VSS, AC voltage climbs with acceleration.

The speedo unit has power, when connected, the needle drops to "0" and holds there, I don't believe odometer motor is working either.

Thanks a lot for any insight you guys can pass along!

Any details on your setup? Sounds like you are trying to install a 90-91 electronic speedo cluster? Are you LS swapped?

 

[mrjeffyt]

I just installed a blueprint 355 and an nv3500 5 speed. I have most of the electrical from a K5 to include the cluster and DRAC module, I also have a DRAC from my donor vehicle, 95 C1500 and an electronic cluster from a G10 and even with a different DRAC and speedo head I get the same result. Is it possible the VSS, though generating a signal, could be weak?

One thing that may be normal, but I find odd is that the AC voltage put out by VSS changes with vehicle speed as it should, but I get 0 volts when connected to either DRAC unit

 

[mrjeffyt]

Well, I guess there aren't a lotta people that have played with this setup, doing my own research, it looks like I might need an oscilloscope to read the output to the speedo, also need to learn more on the sending unit in the transmission, not sure if the strength behind the AC voltage is important, but I'm curious as to whether or not the voltage isn't actually a strong enough signal to make it through the unit to be translated into digital pulses that the speedo understands

 

[mrjeffyt]

It's all good!

Well, just to update, I used existing wiring that fed from the engine bay into the cab, I'm assuming it was feed for the TBI setup, and I accidentally discovered that of of the wires that I connected to the VSS and spliced into inside to connect to the DRAC unit was originally a ground. There was a GM split that was hidden in electrical tape and grounded out. After clipping that connection, the speedo worked! Now I've finally gotten an OEM K5 speedo to work smoothly and accurately. If your considering going this route, I would recommend it! It looks clean and like I got it that way, and it actually finally works! I just changed my gears and was able to simply do some math and adjust my toggle switches on my DRAC to compensate at the speedo! It's awesome! And it was very cheap having sourced all GM used pieces!

 

[yevgenievich]

Turned out to be a simple problem. Glad it works.

 

[foamypirate]

Well, just to update, I used existing wiring that fed from the engine bay into the cab, I'm assuming it was feed for the TBI setup, and I accidentally discovered that of of the wires that I connected to the VSS and spliced into inside to connect to the DRAC unit was originally a ground. There was a GM split that was hidden in electrical tape and grounded out. After clipping that connection, the speedo worked! Now I've finally gotten an OEM K5 speedo to work smoothly and accurately. If your considering going this route, I would recommend it! It looks clean and like I got it that way, and it actually finally works! I just changed my gears and was able to simply do some math and adjust my toggle switches on my DRAC to compensate at the speedo! It's awesome! And it was very cheap having sourced all GM used pieces!

Thanks for checking back in and updating us! I've got a 91' Speed in my 88' for my LS swap. It's nice having trip and a 6 digit odo, but man, it hates humidity. It acts really funky until it dries out.