When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I'm in the process of Ls swapping my 84 c10 that my dad gave me. He's the 2nd owner and bought it with 20k miles. It now has 420k miles and he decided to hand it down to me. I drove it some to high school with the Diesel engine and blew it up, now has a sbc 327. I'm wanting to retain the original gauges. So I bought a cluster from an 91 suburban. The drac module sends out a 4000 p/m to the speedo. And from I've researched so does an ls1 PCM. can anyone verify if you can just send the speedo wire from PCM to the speedo? Thanks for any advice.
Well from what iv found out, the old drac module sends out ac signals and new Ls pcms send out DC signals. Or vice Versa. So I was curious if anyone had personally tried hookin it to a factory speedo
Cool! That's what I wanted to know. I would have if the 84 speedo was electric but it was cable and quit workin anyways. So I took the electric one apart and rolled it back to 0s. Figured it was worth it for an Ls swap ha
You can actually change the PPM in the ECU for the Speedo, so even if they don't match 1:1, you can just change the setting in the ECU until its correct. My speedo takes 16000 PPM, 15 seconds later, that's what the ECU was sending to it.
I agree with ls1nova71. Did the exact same swap on my 85 GMC and all I had to do was make sure the gear ratio and tire size was correct in the PCM. Every thing was fine.
Yes, you can change the PPM in the tune, but GM speedos use a 4000ppm signal so you shouldn't have to change it. As long as your gear ratio and tire size is correct, it will read correctly.
I wasn't thinking when I said I would have left the miles on the odometer, duh, that would have been on the old speedometer....
Haha ya old cluster is gone. Got the electric one in this eve. Swapped all the wires on ghe connector and hooked up the vss wire and even put in the wire for MIL light for the Ls swap. Kinda hard to see in the pic but it lights up better than old one. Very happy with it.
so on mine I have a three "wire" ribbon cable coming from the drac to the speedo, how did you wire that up? signal, power and ground I assume....but which goes where?
I followed this pin diagram and swapped all the wires on the cluster connector. I checked for power and ground going to the speedo and it had 12v. I added a wire at pin 18 for vss but did not hook it up to anything as I'm still running the sbc and its my daily. I was thinking of adding the tone wheel and speed sensor with a different tail housing and trying to get it work but figured it wasn't worth if I plan on Ls swapping it. I also went ahead and added a wire at pin 16 for the MIL light for the Ls engine. All the other gauges work properly so I'm hoping the speedo will as well down the road.
Well I got the ls3/60e swapped in and got to the speedo. Hooked up the vss wire from PCM to the speedo, put truck in gear and BAM! Speedo started moving. Couldn't believe it. Had my efilive hooked up and it matched the vss on my log. I'm super stoked!
07-27-2016, 01:26 PM
1984 c10 Ls swap electronic speedo questions 
