PCM Tune - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**dec010974** · 01-16-2016, 10:05 PM

I'm just fishing. Will this work for removing vats and making minor adjustments to settings on a pcm? I know its impossible to run any lsx with amount of The wires this harness has. The Pcm will be powered/Ground by a switch or automotive battery. The pcm will 12v+ power, 12v+ Ignition Power, Ground, and a feed for the OBD 2 communication.

solidaxel · 01-16-2016, 11:05 PM

How many ground connections are you going to have when finished with the re wire, including the ECM ?

**dec010974** · 01-17-2016, 09:10 AM

Quote:

Originally Posted by solidaxel

How many ground connections are you going to have when finished with the re wire, including the ECM ?

Sorry I don't understand you. This is what I call a PCM tune harness. It will only be used to read data on a PCM. It's not used to drive a car. This PCM harness has 4 grounds on pins #1, #40 on both the blue side and the red side of the PCM connectors. It has 12v+ power and 12v+ Ignition on pins #19, #20, #57, and #75 on the blue side. Pin#58 on the blue side will pull data from the PCM via the OBD2 port. I hope this answers your question solid axel. Just for kicks I can make a nice custom length LSx harness from this.

**LockDoc** · 01-17-2016, 12:54 AM

Quote:

Originally Posted by dec010974

I'm just fishing. Will this work for removing vats and making minor adjustments to settings on a pcm? I know its impossible to run any lsx with amount of The wires this harness has. The Pcm will be powered/Ground by a switch or automotive battery. The pcm will 12v+ power, 12v+ Ignition Power, Ground, and a feed for the OBD 2 communication.

It will if you have a tuning software program like HPTuners.... That is a benchtop tuning harness. It won't do anything by itself. I built a harness like that and using HPTuners removed VATS, rear 02 sensors, and emissions from one of my PCM's on the kitchen table. Here is a thread I posted on my setup:

http://67-72chevytrucks.com/vboard/s...d.php?t=690104

LockDoc

BR3W CITY · 01-17-2016, 01:56 AM

Should work assuming your planning on just using it as a bench device like LocDoc said. You'll get a ton of MIL's lighting up and errors, but none of them would prevent you from accessing and reading/writing data to the ECM through HPT or EfiL.

Thats basically how most mail-order ECM tuners are doing it for you when you send them your ECM.

Just be careful that you can maintain the +12v the entire time, because if you drop voltage during a read/write you'll brick the ECM.

**dec010974** · 01-17-2016, 08:59 AM

Thanks for your replies. You guys are worth a million bucks. The reason I created this because 1) I want familiarize myself with efilive or hptuners and start tuning my own swaps and 2) the guy that tunes my vehicles can never access stuff quickly. He always says "it needs to be in a car that I'm tuning." Once the swaps are complete I want to run the car just to see if everything works. After every LSx swap I gotta Send the PCM to someone else. That's getting old. Also what's the preferred tuning software of choice, HP or EFI.

aknovaman · 01-17-2016, 09:33 AM

FYI You don't need the red connector to bench flash the PCM. Only one ground wire is needed as the PCM case is grounded to all the ground pins via the circuit card.

**dec010974** · 01-17-2016, 11:23 AM

@ aknovaman, thanks. I've see your YouTube channel. It's very impressive. I just hope I get to be half the enthusiast/craftsman, you are.

aknovaman · 01-17-2016, 11:26 AM

Let me know if you need help in any way.

01-17-2016, 08:59 AM	#6
dec010974 Senior Member Join Date: Oct 2012 Location: Miami, Florida Posts: 959	Re: PCM Tune Thanks for your replies. You guys are worth a million bucks. The reason I created this because 1) I want familiarize myself with efilive or hptuners and start tuning my own swaps and 2) the guy that tunes my vehicles can never access stuff quickly. He always says "it needs to be in a car that I'm tuning." Once the swaps are complete I want to run the car just to see if everything works. After every LSx swap I gotta Send the PCM to someone else. That's getting old. Also what's the preferred tuning software of choice, HP or EFI.

01-17-2016, 11:23 AM	#8
dec010974 Senior Member Join Date: Oct 2012 Location: Miami, Florida Posts: 959	Re: PCM Tune @ aknovaman, thanks. I've see your YouTube channel. It's very impressive. I just hope I get to be half the enthusiast/craftsman, you are.

01-17-2016, 11:26 AM	#9
aknovaman Registered User Join Date: Aug 2013 Location: Tecumseh Posts: 355	Re: PCM Tune Let me know if you need help in any way. __________________ Current project 1959 Willys = GEZR TRUK Geezer is a Latin compound word made up of two roots. Gee meaning Urine Stain and Zer meaning your pants are open! FMCDH GBU and GBA http://www.youtube.com/user/aknovaman/videos

01-16-2016, 10:05 PM	#1
dec010974 Senior Member Join Date: Oct 2012 Location: Miami, Florida Posts: 959	PCM Tune I'm just fishing. Will this work for removing vats and making minor adjustments to settings on a pcm? I know its impossible to run any lsx with amount of The wires this harness has. The Pcm will be powered/Ground by a switch or automotive battery. The pcm will 12v+ power, 12v+ Ignition Power, Ground, and a feed for the OBD 2 communication. Attached Images

01-16-2016, 11:05 PM	#2
solidaxel Registered User Join Date: Dec 2002 Location: Cactus Patch So. Az Posts: 4,749	Re: PCM Tune How many ground connections are you going to have when finished with the re wire, including the ECM ? __________________ 53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD) 53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25 55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73 62 Solidaxle Corvette Roman Red (327 340hp 4spd 3:36) C4 & C5 suspension tube chassis LS 3 4L70E 65 Corvette Coupe 327 350hp 4spd 4:11 78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42 2000 S-Type 3.0 (wife cruiser) 2003 GMC SCSB 5.3 4L60E 3:42

01-17-2016, 01:56 AM	#5
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: PCM Tune Should work assuming your planning on just using it as a bench device like LocDoc said. You'll get a ton of MIL's lighting up and errors, but none of them would prevent you from accessing and reading/writing data to the ECM through HPT or EfiL. Thats basically how most mail-order ECM tuners are doing it for you when you send them your ECM. Just be careful that you can maintain the +12v the entire time, because if you drop voltage during a read/write you'll brick the ECM. __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

01-17-2016, 09:33 AM	#7
aknovaman Registered User Join Date: Aug 2013 Location: Tecumseh Posts: 355	Re: PCM Tune FYI You don't need the red connector to bench flash the PCM. Only one ground wire is needed as the PCM case is grounded to all the ground pins via the circuit card. __________________ Current project 1959 Willys = GEZR TRUK Geezer is a Latin compound word made up of two roots. Gee meaning Urine Stain and Zer meaning your pants are open! FMCDH GBU and GBA http://www.youtube.com/user/aknovaman/videos



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