When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I've been stumped on a couple things. My harness is from a 2004 Avalanche 4x4.
On the C100 I have two wires left that I am unable to determine what to do with:
On the LT1Swap webpage Pin C is the "Ignition 3 Voltage (TP2)". I'm not sure the function of this wire or what to do with it.
On the LT1Swap webpage Pin P is the "AC low pressure sensor signal (CJ2/CJ3). The C1 pin Green 80 is labeled "Low reference AC" so I'm not sure what Pin P on C100 is for or if I need to keep it. (I will be keeping AC and using the PCM to control the AC)
There was a yellow wire on Pin M that went to C1-Blue-Pin 59. It is labeled as Class 2 serial data. There is already a Serial Data wire on Pin 58 that LT1Swap says to run to the OBD2 port. What is the purpose of the Blue Pin 59 (ended in c100-Pin M) and would there be any use to keep it?
Also, I believe the connector in the picture below is for the transfer case for the 4x4. Is this correct? If so, can I eliminate all the wires going into it?
In the picture below I have eliminated all the wires except for the pink power wire from the connector. Is there any reason to keep this pink power wire or can I delete it as well? (the wires going to the bottom have been de-pinned and will be eliminated. The connector shown is the connector in question and the pink wire going to the top of the picture is the only wire left).
That connector is the NSS-Neutral Safety Switch connector. You can DELETE all of it if you would like-as long as you have another NSS somewhere on the vehicle to prevent the engine from starting in any range other than P or N... Also, how will you activate your REVERSE lights? The NSS on the vehicle you took the engine from mounted on the side of the automatic transmission and was responsible for both actions I mentioned above.
Also, be forewarned that there is a single wire in the harness that will need to be GROUNDED if you ever need to use a scanner to do a CRANK POSITION RELEARN. I think it is a Black/white wire... The PCM must be able to see (through that wire) that the trans is in P or N in order for it to allow the process to do the relearn. Hence, ground that wire and it tricks the PCM into thinking it is in P or N.
Look here at PIN 34... http://www.lt1swap.com/2004vortec_pcm.htm It seems like the PCM needs to know when the trans is in P or N so that it will allow a start condition (if you are using a relay for your starter that the PCM controls). I'm doing a '70 Chevrolet C-10 right now and we are not passing the start wire through to the PCM at all as this vehicle has a factory NSS on the column that we are still passing through.
That wire also tells the PCM to raise, or lower the engine idle speeds, and also which tables for RAF to use. If the computer never knows when you are in P or N, then you essentially lose the ability to utilize those extra tables in the tune. I'm sure others will post with additional info that I have not even thought about.
Oh man, thanks. I'm planning on keeping my neutral safety switch. I'm glad I didn't cut all those wires out! Even though I had wanted to keep it, I had no idea the neutral safety switch controlled all those things.
I've been stumped on a couple things. My harness is from a 2004 Avalanche 4x4.
On the C100 I have two wires left that I am unable to determine what to do with:
On the LT1Swap webpage Pin C is the "Ignition 3 Voltage (TP2)". I'm not sure the function of this wire or what to do with it.
On the LT1Swap webpage Pin P is the "AC low pressure sensor signal (CJ2/CJ3). The C1 pin Green 80 is labeled "Low reference AC" so I'm not sure what Pin P on C100 is for or if I need to keep it. (I will be keeping AC and using the PCM to control the AC)
There was a yellow wire on Pin M that went to C1-Blue-Pin 59. It is labeled as Class 2 serial data. There is already a Serial Data wire on Pin 58 that LT1Swap says to run to the OBD2 port. What is the purpose of the Blue Pin 59 (ended in c100-Pin M) and would there be any use to keep it?
Also, I believe the connector in the picture below is for the transfer case for the 4x4. Is this correct? If so, can I eliminate all the wires going into it?
In the picture below I have eliminated all the wires except for the pink power wire from the connector. Is there any reason to keep this pink power wire or can I delete it as well? (the wires going to the bottom have been de-pinned and will be eliminated. The connector shown is the connector in question and the pink wire going to the top of the picture is the only wire left).
Thank you,
Brandon
1 You should trace it back and find out what it goes to, odds are it went to something you no longer have, but trace it to be sure.
2 Goes to the low pressure switch on the accumulator, but not sure how you are going to get the A/C to work going through the PCM with your set up.
3 Pin 59 is a dedicated data line to the BCM, you wont need it.
As for the NSS plug, most wires go to the PCM so you would just leave them and not do anything with them, the starter and back up light wires are optional and can be used or removed if you are using the original NSS on the column.
Not sure what that last pic is of, but looks like an oxygen sensor plug? If so, just delete the power wire going to it.
Thanks, I really appreciate it. I just traced those two wires from the c100 and they both go to two plug ins that are next to each other on the loom. Each plug in has two wires, the one going to the c100 and a ground wire. The plug ins are completely nondescript and aren't unique.
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.
More Wiring Questions 
