Guide for LQ4 Swap into 1999 K2500

[xXxPARAGONxXx]

There's a lot of info to sift through on the internet, but to save time, does anyone know where I can find a definitive guide to swapping an LQ4 into a 1999-2000 K2500 Crew Cab (with L31, MT1, and NP241)?

After considering the cost of a new L31 HD crate engine ($4300), and seeing how plentiful and cheap the LQ4 is, I'm seriously considering the swap.

Some considerations:

- I am planning on installing a hydroboost unit, so I need to retain that.
- I do not want to splice into my stock engine/transmission harness. I can swap connectors, if necessary, but I want to avoid splicing if possible.
- I want the finished product to look OEM (i.e., like the engine came installed from the factory).
- I would like to use the 0411 PCM.

Advice and recommendations are greatly appreciated.

 

[Alteca]

What transmission do you plan on using?

 

[xXxPARAGONxXx]

What transmission do you plan on using?

My truck has a 4L80-E (MT1), and I would like to keep it.

 

[stutaeng]

I don't know all of the answers, but some information:

The hydroboost is not a problem. You can tee into the return hose or get a PS pump from the hydroboost setup. All LQ4s came with hydroboost, so they already have the cap on the intake where the vacuum hose would go for vacuum assist brakes.


Wiring harness: you bring in the entire complete wiring harness. Your transmission will work just fine. The LQ4 was mated to the 4L80e from the factory. I believe the early LQ4 had drive by cable, which should work just fine with your throttle cable. The 0411 and the P01 ECU should work, which are the red and blue connectors. iIRC.

Aftermarket engine mounts locate the LQ4 correctly. There's tons of options.

What I don't know is guages and AC...how that works into the GMT 400, but I believe they can be made to work.

4x4 should also be easy to keep electronics-wise.

 

[Dropped88]

I don't have a guide but I can answer any questions you have.

You can retain hydroboost, you don't have to change any of your power steering system the factory will bolt to the LS bracket.

You also don't have to splice wires you can make it plug n play like factory. I think worst when wiring was I had to splice 2 wires together because they needed to go to same pin on pcm.

And the PCM doesn't have to have the "0411" service number it just needs to be a 99-02 red/blue connectors PCM.

As for looking mostly stock is what I went for, I'm actually getting a stock air box tomorrow or Saturday and see about mocking it up to work.

Also all my gauges work, idiot lights, cruise, ABS, AC.

Can use your transmission I'm using 4l80 that came in truck

 

[Alteca]

MuscleRods 88-98 GM truck LS Conversion Kit

Evolve that classic GM muscle car into a fuel efficient, ground pounding Muscle Rod using LS swap products from BRP Muscle Rods

www.brphotrods.com

This website sells just about any part you would need including plug and play wiring harnesses. Although I would just use the lq4 harness like others have said.

For your gauges, You can get an adapter to use your factory oil pressure gauge. For coolant temp, you can get a factory range sensor and install on the passenger side of the block. I believe for your Speedo, you can run the lq4 harness vss wires parallel to your factory vss harness.

 

[stutaeng]

I don't have a guide but I can answer any questions you have.

You can retain hydroboost, you don't have to change any of your power steering system the factory will bolt to the LS bracket.

You also don't have to splice wires you can make it plug n play like factory. I think worst when wiring was I had to splice 2 wires together because they needed to go to same pin on pcm.

And the PCM doesn't have to have the "0411" service number it just needs to be a 99-02 red/blue connectors PCM.

As for looking mostly stock is what I went for, I'm actually getting a stock air box tomorrow or Saturday and see about mocking it up to work.

Also all my gauges work, idiot lights, cruise, ABS, AC.

Can use your transmission I'm using 4l80 that came in truck

The engine looks like it came like that from the factory!

How did you make your guages work? I know LT1swap.com has some information, but I've never done this swap myself, so don't know the fine details...

What about the AC? How did you make that work?

I think the early ECU GMT800s have basic on-off switches, which is similar to the GMT400. The later ECU 800 have more complicated AC controls, the ECU tries to anticipate when the AC compressor will kick in, and adjusts the throttle (drive by wire, obviously) so you don't get that little "jog" when the compressor kicks in...I think that's what I read on LT1 swap...?

 

[OutlawDrifter]

I'm not sure if its still available or not, but member lextech had an AC compressor bracket to retain the factory compressor.

ICT Billet (great USA company...located here in KS) offers one as well, that should allow you to use the factory lines:

https://www.ictbillet.com/ls-swap-9...essor-power-steering-bracket-ls1-ls3-lsx.html

Don't let all the spaghetti scare you, wiring them up isn't that bad at all. You will have to make a couple of connections to LS harness with your factory stuff, and some of that has been outlined here. There are multiple ways to make the gauges work, whether it be adapters to use the stock senders, using a 1998 Fbody LS1 3-pin water temp sender, etc, etc.

Hop on LS1tech.com and spend a couple of weeks reading, that should give you enough info to LS swap the space shuttle

A stand alone harness would be a great place to start, there is a member on a few forums, aknovaman (he also has a youtube channel), that does awesome work. He is actually who I use for a tuner, and he built the harness that is in my '49 GMC.


Here is a great writeup on a K2500 'burb that PolarBear did:

https://www.gmt400.com/threads/1993-k2500-suburban-tow-pig.47993/

 

[0xDEADBEEF]

If you don't modify your stock harness you will have a bunch of unused connectors hanging around, something to consider.

 

[xXxPARAGONxXx]

If you don't modify your stock harness you will have a bunch of unused connectors hanging around, something to consider.

Understood. Seeing that wiring modification is inevitable, I think I can accept that. I'll look for the best means to do so to keep it looking OEM.

Another question I have is —

Currently vehicle is drive-by-cable. Is modifying it for drive-by-wire necessary? I have seen some websites that offer a conversion pedal. Still trying to determine which would is the best quality.