NBS cluster with LS swap?

[slow_c1500]

When I do an LS swap id be looking at a 99-02 donor vehicle anyway, since I want clutch fans and drive by cable. Id consider using the NBS cluster too if it will simplify the wiring process compared to adapting the harness to the OBS cluster.

 

[AK49BWL]

Honestly I don't think it'd be that much different. But let's compare just for the fun of it

Shared between years (so your LS harness will already have these): Tach, VSS/Speedometer, Oil Pressure Gauge, SES light

NOT shared, so you'd need to add wires to the cluster for: Engine Temp, Fuel Gauge.

Fuel gauge can be configured in the PCM for PWM output to the gauge, one wire from PCM to gauge and that's done. Engine temp is a little more iffy, you might need to install a temp sensor somewhere as I don't think the PCM has an output for that... 96+ GMT400's have two temp sensors, one at the thermostat housing for the PCM, and one in the driver side head for the gauge.

You would actually lose a few things converting to the early GMT800 cluster, stuff that is controlled by the BCM in those trucks like the high beam indicator and transmission shift indicator readout, possibly other indicators like seat belt, etc etc. I'd stick with the standard GMT400 cluster personally.

 

[slow_c1500]

Got it. So if I wanted to do an LS swap with as little custom wiring as possible, im guessing my best bet is to keep the OBS cluster and fusebox, and then buy a premade LS swap harness. Ive tried to understand how to make your own harness from the two but the youtube videos are as clear as mud

 

[99xcss4]

https://www.ebay.com/itm/1451347726...srucUPZSDQD4G3Duk2rzGl93ihJC|tkp:BFBMwpHrmv9j https://www.ebay.com/itm/3146150366...M13rR0blKFGKfYVB3by3bONrbg|tkp:Bk9SR8KR65r_Yw https://www.ebay.com/itm/3645921870...GQJa+oc0kxqghoLuVNmV8ySEry|tkp:Bk9SR8SR65r_Yw

 

[KansasOBS]

Got it. So if I wanted to do an LS swap with as little custom wiring as possible, im guessing my best bet is to keep the OBS cluster and fusebox, and then buy a premade LS swap harness. Ive tried to understand how to make your own harness from the two but the youtube videos are as clear as mud

There are some yt videos that are more helpful than others. Really once you start stripping/labeling, and working through it, things become a little clearer.

But yeah, I wouldn't bother with the nbs cluster, and trying to sort out that mess. The obs cluster works very simple, just use the obs senders, and done.

When I did my swap, there were actually enough blank spaces in the OBS fuse box, that I just cannibalized an extra one that I had, and added the LS fuses into it. Factory appearing, and clean.

 

[Drunkcanuk]

Got it. So if I wanted to do an LS swap with as little custom wiring as possible, im guessing my best bet is to keep the OBS cluster and fusebox, and then buy a premade LS swap harness. Ive tried to understand how to make your own harness from the two but the youtube videos are as clear as mud

Watch this series.
If you're confused after these....buy one! Lol
Just kidding, but this is probably the best I've come across.

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[slow_c1500]

Pardon the newb questions, but i watched that series and did a lot of other research and I have essentially gathered that the basic wiring process is: (correct me if im wrong)

1. de-pin everything from the pcm connectors on the OBS harness, remove all the engine control related stuff, but keep the AC, gauge senders, ABS, etc.

2. locate wires from LS harness that will be tied into OBS harness and snip the wires (to be mated later) but keep them in the pcm pins. Keep all the engine control related stuff obviously

3. mate the wires from the 2 harnesses that go to the non-engine related stuff (ABS, AC, gauge senders, etc)

4. now you've got one big harness that has everything

 

[Drunkcanuk]

Pardon the newb questions, but i watched that series and did a lot of other research and I have essentially gathered that the basic wiring process is: (correct me if im wrong)

1. de-pin everything from the pcm connectors on the OBS harness, remove all the engine control related stuff, but keep the AC, gauge senders, ABS, etc.

2. locate wires from LS harness that will be tied into OBS harness and snip the wires (to be mated later) but keep them in the pcm pins. Keep all the engine control related stuff obviously

3. mate the wires from the 2 harnesses that go to the non-engine related stuff (ABS, AC, gauge senders, etc)

4. now you've got one big harness that has everything

This may be the whiskey talking.....but ya, sounds about right! Lol
Get the pin out sheets he mentions, from your year truck and year of the donor ECM. And get to trimmin and de-pinnin! Lol

 

[jus10inbrla]

Make your own & retain all indicators you want / add any extras

 

[slow_c1500]

What must be done for the fusebox, and do I use the OBS or NBS box?