jdustin

I have a 99 suburban that I just put a 5.3 truck engine in with the matching 4l60e 4x4. My question is I am running 2 pcms .I need the original for my abs and other things as well. I have the old harness and new harness and fuse box installed. What do I do about the transfercase since my speed sensor is on it? I currently have the original harness as well as the new one in right now but dont know how i should do the the transfer case.

clinebarger

You don't need to run the old PCM or Engine harness in a GMT400 truck when swapping to a Gen III LSX, Wire the T/C VSS to the LS PCM, The trans will not shift without it.

What year/model LS PCM are you running?

jdustin

its a 2000 silverado 4x4. I have seen it done before. The computer in the suburban is still running my fuel pump abs and air bags. I have it running but have not drove it yet. I am using the new harness for the engine and the old one for the nuertal safty switch and transfercase. My suburban still has to run some things. I might just have to jump a wire for vss from one computer to the next than my factory speedo will work as well...idk well see

clinebarger

Your 0411 "LS" PCM has a 128K per mile output (Rear wheel speed input) for the ABS, Pin 49 C2 Red, Right next to the 4K output for the speedometer (Pin 50).

The 0411 PCM also has it own Fuel Pump controls, Without a rpm signal to your old PCM, I don't see the Fuel pump working???

Your Air Bags are stand alone, No PCM inputs/outputs.

The '99 Burb MLPS/NSS wiring can be culled out of your old harness....Nothing to do with the PCM.

jdustin

i am using fuse box and computer and harness from the 5.3. Iam allso useing the fuse box and computer in the suburban. The suburban is running the fuel pump just fine. All I did was power up the 5.3 fuse box and pcm and it started right up with my suburban running the fuel pump. If you go to youtube you will see a few videos with people doing the same thing. its pretty easy. Im jus not sure on how to get my transfercase working . I will probobly jus jump the vss signal from one pcm to the other.

clinebarger

I have done several '88-'01 GMT400 platform LS swaps, But your on a different path than I would take, Your doing a Standalone, Where..... Integration is far more simple.

I have never tied into VSS Sensor wiring for any reason, I'm curious if that works out for you?

jdustin

Hey you were right on the fuel pump thing it only would let it run for about a min than it shuts off. I got that switched over to the 5.3 pcm and works good now. However Iam having a problem with the transmission not shifting. I saw that you had helped someone else on a nother forum and was hoping you could steer me in the right direction. Iam pretty sure its a speed sensor problem but Iam confused about why its not working. Does the transfercase have two speed sensors because thats what it looks like.???

clinebarger

There is only 1 VSS sensor, Toward the rear-top of the T-case.

Here is a pic of a "Modified" NP241, The White sensor is the Range Switch(White arrow), The Black Sensor is the VSS (Red arrow).

If you have the Original PCM tied into the VSS wiring......Undo that.....And run the VSS directly to the 5.3L (0411) PCM, And see if it shifts now.

jdustin

I switched the vss signal from the suburban pcm to the 5.3. ..and nothing changed. according to all data and what I see it has a front propeller speed sensor and a rear propeller shaft speed sensor. I see two sensors but can only find the one on the electrical wiring diagram..any ideas????

Patrick Carter

Take the ls vss an splice it into the obs wire on the t case problem and don't use the 128k use the lower number .....I have a 97 that I am putting a ls in and I got everything situated besides a few things

WildBillsPerformance

What are you guys doing to make the electric shift motors work on the transfer cases when doing a swap?

mrvedit

WildBillsPerformance:
First, welcome to the forum!
Second, please don't post on old threads as it is very annoying to those people who generously donate their time to answer as many new questions as possible. Posting on old threads, forces them to re-read these old threads, but honestly they just skip them.
You are welcome to start your own thread.
This thread is now closed.