94 Suburban speedo

[rs359]

We have just completed one of two 12valve 2wd Suburbans I have all the gauges working except the speedo . The trans is a 94 47rh. I need to know if anyone has figured this one out . I found a signal converter on Dakota Digitals
website but I need to know what type of signals were used for the Chevy and the Dodge. Thanks Rich:thankyou2:

[Chevycummins]

X2^^^ i did the conversion in my 94 pickup and kept all stock wires and sensors and mine still doenst work along with odometer

[rs359]

Your sensor should be in the transfer case I think I read somewhere on another 4x4 they unplugged something on the computer and it started working .It doesnt hurt to try. Rich

[Chevycummins]

Your sensor should be in the transfer case I think I read somewhere on another 4x4 they unplugged something on the computer and it started working .It doesnt hurt to try. Rich

my ecm is completely unplugged and nothing still.

[rs359]

maybe plug it all back in and unplug each one one at a time . But you have to have your original speed sensor . Rich

[Chevycummins]

maybe plug it all back in and unplug each one one at a time . But you have to have your original speed sensor . Rich

yeah i got the original everything except temp guage and it is mechanical but ill try one at a time i plan on taking a volt meter to it and measuring the ohms at the plug and making sure that the power is there also.

[rs359]

I went back and reread the post where I first heard of someone having a working speedo you were the threadstarter and Turbojoe said to unplug the center computer plug.
The temp and oil just use the factory sending units and if you have a tach you must use the Chevy Alt

[turbojoe]

that only apparently works on the newer 6.5 trucks, cuz i did a 97 454 suburban and unplugging the connectors doesnt do anything.

Joe

[Chevycummins]

I went back and reread the post where I first heard of someone having a working speedo you were the threadstarter and Turbojoe said to unplug the center computer plug.
The temp and oil just use the factory sending units and if you have a tach you must use the Chevy Alt

yes i know i have done that i have unplugged the whole thing done one plug and then another and another still nothing i checked all fuses no blown fuses and all have power i am missing something somewhere power or not enough ohms and i know about the other things because i have all those except my speedo thats what is bugging me and with it being my DD and living in the city with no shop or tools its difficult to set and do one evening i am just looking into this thread also maybe someone else with another idea might pop up since my old thread is a ways back. thanks for any info


michael

[rs359]

I called some conversion places and apparently noone has ever gotten a gm speedo to work with a dodge trans I think I have found a way. see this link.

http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=126/category_id=287/home_id=59/mode=prod/prd126.htm

Dang what a link I hope it works .Anyway it doesn't do any good if we cant make it work with the original sending units . I have the complete wiring diagram for a 94 and it seems the signal goes to a vehicle speed sensor buffer (wich is grounded at the firewall )then into the computer as a vehicle speed sensor and as a trans output sensor the computer then drives the speedo. Check to see that all black wires from the firewall harness are grounded. Rich

[Chevycummins]

I called some conversion places and apparently noone has ever gotten a gm speedo to work with a dodge trans I think I have found a way. see this link.

http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=126/category_id=287/home_id=59/mode=prod/prd126.htm

Dang what a link I hope it works .Anyway it doesn't do any good if we cant make it work with the original sending units . I have the complete wiring diagram for a 94 and it seems the signal goes to a vehicle speed sensor buffer (wich is grounded at the firewall )then into the computer as a vehicle speed sensor and as a trans output sensor the computer then drives the speedo. Check to see that all black wires from the firewall harness are grounded. Rich

thats some good info rich thanks i will try and get a chance to trace some wires i might have to break down and go to the parts store and get a wire diagram for my truck.:Cheer:

[rs359]

Pm me a Email and I will send it in pdf form
Rich

[rs359]

Ok according to GM the speedbuffer is called a DRAC and it might be possible to go from the drac straight to the speedo bypassing the computer.Rich

[rs359]

The DRAC sends out digital pulses at 2,000 per mile to the engine computer and speedometer, 4,000 pulses per mile to the cruise module, and 128,000 pulses per mile to the ABS computer. Most GM vechicle utilize a 40 tooth gear inside the transmission tailshaft.
So it would seem that the signal wire from the drac could be rerouted directly to the speedo and the computer could be eliminated for those of you running the GM sensor.
Those of us running Chrysler transmissions will have to remove the drac and install an adapter of sorts . But we still need to find out the PPM (pulses per mile) of the Dodge VSS Rich

[rs359]

I found the dodge ppm it is 8000 which is the same as a lot of aftermarket senders. The Dakota Digital unit should work along with or without the drac unit. I am going to try and bypass the drac and the ecm and send the signal straight to the speedo .
Unfortunately the first Burban had to go to the trans shop (new trans and it wont hardly move) so it will be a while before I can put my findings into this truck. Rich

[Dazed&Confused]

Just subuscribeing to the thread to see how you all got it working. What did you guys do for shift cables?

[rs359]

Truck is in the shop having AC lines made up and complete AC overhaul . Just got in the module from dakota digital I will post my findings. Shift Cable is a lokar column cable adapter with a B&M Chrysler cable shift lever.

[rs359]

IT WORKS I finally got time to hook it up and found it had a bad speed sensor after fixing that it works . All of the factory gauges are working now.Rich