1995 C2500 ls1 swap

[Jeebalow]

I'll reply to your PM here so the info isn't hidden and someone that searches can see it.

so im finishing up the wiring on my 95 swap...im using a nelson harness and it has a green speedo wire. Iv been told to find the DRAC module behind glove box on pass side, remove harness, snip blue wire w/black stripe and red wire /black stripe and hook them together then hook to my green wire from nelson harness. Is this what you did?

The drac on my 95 doesn't have those colors and I am willing to bet yours doesn't either. Here is what the wire colors for mine (95 C1500) are and what they do

Dark blue - to 95 PCM
Dark green - to gauge cluster and spare cavity convenience center
White - brake pressure modulator
Purple/white - VSS in
Brown - to 95 PCM
Pink - Fuse 4 (Gauges)
Black/white - Ground
Green/black - VSS in
Dark green/white - cruise control module and stereo

So if you just want to get the speedo working you can splice into the dark green wire anywhere along the wire. You can do it at the drac or behind the cluster.

Here's what I did. I took the dark green/white and dark green wire and spliced those together and connected them to the dark green speed wire from the LS PCM. So both speedo and cruise control module get speed signal. I am assuming that they both use the same signal and that these were the red/black and lt blue/black wires they spliced together, but am not 100% sure yet. I still haven't gotten the truck on the road to verify whether this works. I guess we'll find out soon enough. Feel free to give it a shot and let us know if it does work.

[chvy=power]

I'll reply to your PM here so the info isn't hidden and someone that searches can see it.



The drac on my 95 doesn't have those colors and I am willing to bet yours doesn't either. Here is what the wire colors for mine (95 C1500) are and what they do

Dark blue - to 95 PCM
Dark green - to gauge cluster and spare cavity convenience center
White - brake pressure modulator
Purple/white - VSS in
Brown - to 95 PCM
Pink - Fuse 4 (Gauges)
Black/white - Ground
Green/black - VSS in
Dark green/white - cruise control module and stereo

So if you just want to get the speedo working you can splice into the dark green wire anywhere along the wire. You can do it at the drac or behind the cluster.

Here's what I did. I took the dark green/white and dark green wire and spliced those together and connected them to the dark green speed wire from the LS PCM. So both speedo and cruise control module get speed signal. I am assuming that they both use the same signal and that these were the red/black and lt blue/black wires they spliced together, but am not 100% sure yet. I still haven't gotten the truck on the road to verify whether this works. I guess we'll find out soon enough. Feel free to give it a shot and let us know if it does work.

awesome man thanks for the clarification! Ill pull the drac harness out toning and take a look at it...im still about 2-3 months away from firing it up. Just sent the L92 heads off my LY6 to TEA to get a little work done

[Mickeymotormount]

My '93 wires are different colors. I didn't use the buffer since the PCM has the buffer included inside it(or doesn't use it at all). I ran the cruise wires from the PCM directly to the cruise control module. The only thing I had to get was the brake input to shut down the cruise when the brake is applied. I got this from the rear ABS module which is in close proximity to the cruise module.

[Jeebalow]

My '93 wires are different colors. I didn't use the buffer since the PCM has the buffer included inside it(or doesn't use it at all). I ran the cruise wires from the PCM directly to the cruise control module. The only thing I had to get was the brake input to shut down the cruise when the brake is applied. I got this from the rear ABS module which is in close proximity to the cruise module.

Can you elaborate on the cruise control wiring? What pins and connector do they come from on the PCM and what year engine are you using? My 95 has a standalone cruise module and the only signal missing to it (since I removed the drac) is speed signal, that is why I spliced the two wires together at the drac.

It's also worth mentioning that I got rid of both the DRAC and old ECU.

[chvy=power]

Jeebalow you were right about the color wires at my drac module. Mine were drk grn/wht and drk grn. I also tossed my drac module in the trash

[Jeebalow]

Jeebalow you were right about the color wires at my drac module. Mine were drk grn/wht and drk grn. I also tossed my drac module in the trash

Good to know! Makes sense that they would be the same in all 1500/2500/3500. I got that information from alldatadiy, but it only gives me year and model specific info so I couldn't look it up for a 2500. Glad that helped!

[Mickeymotormount]

My engine is a '99 6 liter and it's PCM. I will have to track down the wiring for you. I used the '99 GM truck service manual wiring diagram along with the '93 Chevy truck wiring diagram manual to get the wiring schematics.

If you haven't already checked out this site, do so. It was immensely helpful in getting the wiring ironed out.
http://lt1swap.com/99-02_vortec_pcm.htm