1995 C2500 ls1 swap

[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

[Jeebalow]

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

Mickey, I did use that site to rework my 2001 harness. The reason I asked about wiring is because the 99-02 PCM only has a cruise control enable wire (I checked on lt1swap.com before asking) . AFAIK, other than that, the rest of the cruise was handled by a cruise control module.

From your post above it seemed as though you were using the new PCM for cruise or you are using the 99 cruise control module. As I understand it, you should be able to just give the obs cruise module the speed signal it needs and it will still function exactly as it did before. The rest of the wiring to it should be untouched during the engine swap. Can you clarify what you did a little more. Not necessarily "this pin to this pin connected" , but more general "I used the 9X cruise module and LS pcm".

[Mickeymotormount]

I actually wanted to use the '99 cruise module. I took it from the donor truck but it was defective. After multiple attempts to wire it and not have it work, I figured I'd try the '93 module originally equipped with the truck. It ended up my original wiring was correct and made the '93 module work like a charm. What I can do is pull out my '99 service manual, scan the cruise control schematic, and then post it here. Hopefully this will help you. It has been about 3 years since I swapped engines so things are a little fuzzy.

The reason the PCM is involved with the cruise in the first place is that while in cruise, the PCM alters shift patterns so there is seamless performance while in cruise control. If you have 4 wheel drive, there is also a 4 wheel enable wire that lets the PCM know when the transfer case is in Low gear. This allows the PCM to shift the trans while the transfer case is in low gear. Originally, I left this wire unconnected, later to find out that, while in the transfer case was in low range, the transmission would not shift out of 1st gear. Hooking up this wire to the transfer case low switch allowed the PCM to shift the trans while in Low gear range.

[Jeebalow]

I actually wanted to use the '99 cruise module. I took it from the donor truck but it was defective. After multiple attempts to wire it and not have it work, I figured I'd try the '93 module originally equipped with the truck. It ended up my original wiring was correct and made the '93 module work like a charm. What I can do is pull out my '99 service manual, scan the cruise control schematic, and then post it here. Hopefully this will help you. It has been about 3 years since I swapped engines so things are a little fuzzy.

The reason the PCM is involved with the cruise in the first place is that while in cruise, the PCM alters shift patterns so there is seamless performance while in cruise control. If you have 4 wheel drive, there is also a 4 wheel enable wire that lets the PCM know when the transfer case is in Low gear. This allows the PCM to shift the trans while the transfer case is in low gear. Originally, I left this wire unconnected, later to find out that, while in the transfer case was in low range, the transmission would not shift out of 1st gear. Hooking up this wire to the transfer case low switch allowed the PCM to shift the trans while in Low gear range.

Oh I see. I have a manual trans so I ended up just removing all of the transmission wiring from the LS harness. I will be using the 95 cruise module. I'll report back on whether what I did works or not. It would be nice if the electrical diagrams also included the type of signal that each wire had. It would make this much easier.

Sorry for the thread jack OP

[GreyChevy]

Does your nv4500 have the exterior slave or interior slave? Also do you happen to know the 1st and reverse gear ratio? I was going to stick with the exterior slave when I bought my nv4500 but would rather have a 5.61 reverse ratio than a 6.34.