LS 5.3 Drive By Wire ~ Stand Alone Wiring Harness (TAC Module) Question

[dave w]

I'm simplifying a factory LS 5.3 Drive by Wire harness for stand alone service. The question I have is how to wire the Throttle Actuator Control (TAC) Module Stop Lamp In (STP LP IN) wire Light Blue (LT BLU) pin 6.

From the schematic I have (posted pics below), I'm thinking Ignition Power (On - Start 12 VDC) is sent to the TAC Module when the brake pedal is depressed?

Are the Mitchel's Manual Schematic I posted pics of correct?

Thanks in advance,

dave w

[Caleditor]

I will dig that up for you. I helped LoKar get the DBW setup working that they have on the market

[dave w]

I have information from EFI Connections, see pic below. It seems to me the Mitchel's Manual might not be in agreement with the EFI Connections schematic. The Stop Lamp In are in agreement with both Mitchel's Manual and EFI Connections schematic.

So here is what I'm thinking. Wire both the Stop Lamp In and Brake Switch like the EFI Connections schematic.

dave w

[Buzz]

The EFI Connection schematic appears correct for Gen III (specifically early Gen III).

TCC brake circuit to PCM is a "normally closed" circuit - PCM receives 12 volts of power when brakes are NOT applied - this is used to control TC lockup.

Cruise Control brake circuit is a "normally open" circuit - PCM receives 12 volts of power when the brakes ARE applied - this is used to disengage Cruise Control (for decel or a stop).

What year, make, and model is your donor engine wiring harness from ?

Have all of the GM schematics .....

[dave w]

The EFI Connection schematic appears correct for Gen III (specifically early Gen III).

TCC brake circuit to PCM is a "normally closed" circuit - PCM receives 12 volts of power when brakes are NOT applied - this is used to control TC lockup.

Cruise Control brake circuit is a "normally open" circuit - PCM receives 12 volts of power when the brakes ARE applied - this is used to disengage Cruise Control (for decel or a stop).

What year, make, and model is your donor engine wiring harness from ?

Have all of the GM schematics .....

The donor vehicle was a 2000 1/2 Ton Pickup 2WD - 5.3 liter / 4L60E.

I'm thinking for this conversion, 5.3 liter / TH350 the brake switch wire and stop lamp input wire are not needed?

The schematics I'm using are attached.

dave w

[Buzz]

Wiring harnesses can range from bare bones to highly intricate - depending on the end use, desired functionality, available time, budget, etc.

Neither of those brake inputs are mandatory with a TH350 - with a couple of caveats. Without the TCC brake input wired you won't be able to a execute a CASE Learn (or CKP System Variation Learn) of the PCM - some people never bother doing this anyway. Cruise Control (if desired) is also off the table.

[Caleditor]

The brake input is a MUST for DBW at the PCM. It will go into torque management. When I say Torque Management this term covers some 400 or so parameters that cause Torque Reduction. The calibration on all 2000 calibration will try to reduce torque output if the brakes are held on. With DBW the calibration will prevent a runaway condition like the Toyota's have. email me and I will give you the schematics and other files on DBW. I work at a GM dealer from 7 to 5 every day. I have the good stuff. caleditor@pcmcalibrators.com

[Buzz]

I participate in select automotive Forums as a means of giving back a little - as the industry has been very good to me over the years.

I try to answer questions that people have (whether or not I agree with what they are attempting).

I do not wish to enter into arguments - and will simply cease to participate if a thread heads in that direction.

My personal preference in a custom Engine Wiring Harness includes VSS, Brake, Clutch, and many other inputs. That said, some people opt to exclude these - and that is their choice. There are many vehicles (hopefully all off road) that have not been wired for Brake, Clutch, VSS, or other inputs - and will still operate (these are just a little more difficult to get running well).

The Torque Reduction linked to the TCC brake input circuit is Abuse Management - and is readily tuned out of the PCM - so no problem there.

The Toyota runaway throttle example is very important - this is meticulously monitored in GM vehicles - and significant discrepancies will cause Reduce Power Mode to occur.

Reduced Power Mode is triggered in several ways. A significant difference between the expected and actual APP sensor output will trigger REP Mode, as will a significant difference in airflow been the MAF sensor (actual) and the calculated (or expected) Speed Density airflow.

Nowhere in the diagnostic procedures I have reviewed from the GM Service Manual, does it indicate that the Cruise Control (TAC Module) brake circuit is contributory to the REP Mode diagnostic.

[dave w]

I greatly appreciate all the information and all the opinions from board members!:thumbsup: I feel sharing information and opinions is how everyone benefits and learns! The simple fact that automotive manufactures DO NOT provide manuals on how to program a PCM, or keep technical information under lock and key (password protected) is a challenge to all of us who choose to do retrofits of newer engine management / power train management systems.:mad1:

The harness I'm simplifying is for an off-road application. The customer I have for this harness is in the business of building off-road only vehicles. I've been given an opportunity to become the supplier of LSx simplified harnesses and PCM flashes for this business. The current supplier is out of town a few states away. I was not able to examine a product from the current supplier. From my meeting with this customer, I asked about brake inputs and was told there current supplier did not have wires for brake inputs. During the meeting, I learned the current supplier did not require a VSS input to PCM. It would seem to me the Abuse Mode is defeated by the current supplier, either by setting Abuse Mode Enable RPM's to Maximum or Zero Out Abuse Mode Disable Speed. I really don't know VSS was eliminated, I was not able to read a PCM programmed by the current supplier.

My hopes for this tread is to share as much information as possible on either "How To" or "How NOT To" configure the brake inputs for Drive By Wire.

dave w

[Caleditor]

The simple fact that automotive manufactures DO NOT provide manuals on how to program a PCM, or keep technical information under lock and key (password protected) is a challenge to all of us who choose to do retrofits of newer engine management / power train management systems.:mad1:


dave w

Dave that is not true


The other issue is that I am unable to upload the schematics to my Photobucket today. My internet radio is down also. I have been trying since you started this thread to upload the schematics. The up-loader just sits and spins. This is just a few that I have posted. http://s1106.photobucket.com/user/PCMCalibrator/library/Schematics?sort=3&page=1 The folder is in place, but it is empty


I have a link to a shared file on our website, but I do not want to give out our password to everyone. https://files.secureserver.net/0fmOCWwqSBwsO5

[EagleMark]

Just attach the files here if you are willing to share. Then the information is always here. This site is open to any file needed and if there is a size restriction or issue I change it!

How many times have you searched the internet to find what you need, then get there and the images are gone because they were hosted elsewhere?

[Caleditor]

We have a 100 GB of storage on our site. We had everything on an FTP, but pulled it all off. I would be posting for days

[EagleMark]

I didn't mean post it all... just as you help in a thread, attach the info. Then it will never be lost, like if you linked it to where hosted at a website and things there change? Poof! We all loose info again...

Like this thread is a specific problem and we can always look back on it from a search.

[dave w]

I'm thinking it might be a good plan to leave the brake wire and stop lamp input wires in the harness, should I need to connect them later. I'm thinking I could connect the brake wire to ignition on, so a "brakes are off signal" is continuously sent to the PCM.

dave w

[Buzz]

The PCM is "smarter" than that ... a constant lack of voltage on this circuit (similar to when the brakes are applied) will set DTC P0719 (Brake Switch Circuit Low Input) ... while constant voltage on this circuit (similar to when the brakes are not applied) will set DTC P0724 (Brake Switch Circuit High Input).

As you stated, it might be a reasonable course of action to leave these wires in the wiring harness (just tucked away where you can get at them if need be), until you complete the first one of these off-road vehicles. After that, you will know definitively what you need / don't need on future wiring harnesses for this customer.

Just some thoughts ....

[Playtoy_18]

I haven't done a dbw harness yet,but subscribing for the great info.

[dave w]

Found this information at lt1swap.com ( http://www.lt1swap.com/wiringharness.htm ). One relay to supply brake inputs to both TAC and PCM.:thumbsup: The wire from the brake switch will need to wired to both (spliced together) with the relay input (termainal 85) and TAC module brake switch input. I've decided to use Hella Relays #75601 relays and Hella connectors #75610. Hella relays are used by the factory. I'm thinking why risk using low cost relays that are not weather proof? Cheap is not good:yikes:...good is not cheap!:thumbsup:

dave w

[dave w]

A few pics of the finished harness.

dave w

[JeepsAndGuns]

Thats looks great, nice work. :happy:

[dave w]

Thats looks great, nice work. :happy:

Thanks!

I do a few extra steps not normally done by others who simplify LS wiring harnesses. I'll solder / splice the connections I make. I use weatherproof relays with a weatherproof fuse panel. I use a thick wall shrink tubing with an adhesive for added insurance against the extremes seen with the underhood environment. I use nylon split loom to wrap the harness, its the same quality split loom as the original harness was wrapped in. The trunk / branch method I use to wrap the harness uses more split loom than the original harness, but provides for a quicker and cleaner looking install. The person I helped with this harness really appreciated the level of service and parts I provided.:jfj:

dave w

[devind]

Excellent work Dave, but I would expect nothing less from you. Very clean harness. Some day I will build something with a LS engine and when I do I got your #.
I have been busy building a 64 Ford unibody pickup for my Uncle to take to Good Guys in Fort worth. I c-notched the rear frame and installed a Camaro front clip, I got it down in the weeds and it drives and handles great. All old school stuff no EFI.

5496

[dave w]

Excellent work Dave, but I would expect nothing less from you. Very clean harness. Some day I will build something with a LS engine and when I do I got your #.
I have been busy building a 64 Ford unibody pickup for my Uncle to take to Good Guys in Fort worth. I c-notched the rear frame and installed a Camaro front clip, I got it down in the weeds and it drives and handles great. All old school stuff no EFI.

5496

I'm really liking your work!:thumbsup:

dave w

[dave w]

More update pics.

dave w

[JeepsAndGuns]

Looks nice and clean. Nice work!

CJ-7 ehh, or may be a CJ-5, cant really tell from the pics. Power brakes would definately be the nex thing on my list of things to do after that swap. Lots of go, and not much woah....lol

[babywag]

So what is done with the transmission wires on a standalone harness w/ a manual trans. or a non OD trans.?
Removed from harness? Or, just cut taped up?

Any trans. wires needed to tell the pcm it's a non OD or manual trans.?

What VSS did you use? Is there a cheap speedo cable driven VSS that works in Jeeps? like the TBI 2PRS from jagsthatrun?

[Playtoy_18]

I removed the wiring from the harness completely,if needed at a later time it can always be added.
keep it in there if you know you'll be switching it up though.
The programming determines the trans type.

[dave w]

What VSS did you use? Is there a cheap speedo cable driven VSS that works in Jeeps? like the TBI 2PRS from jagsthatrun?

Below is thread about using the low cost Dakota Digital VSS. http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=620/prd620.htm

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?2677-Speedometer-Calibration-0411-PCM-using-Dakota-Digital-SEN-01-1

There is the option of programming the PCM so the VSS is not needed. I recommend using a VSS for any vehicle that will be driven on the street.

dave w