Plug-in-Play: Installation of standalone LS replacement harness (2023)

Trading an LS vehicle is like putting together a puzzle, but you don't have all the pieces to begin with. It takes a lot of research to figure out what you need, but don't worry, you can find almost anything on the secondary market. Putting an engine into a vehicle is usually an easy task, but what next? Well, you need to understand the fuel system, cooling, exhaust and finally wiring, which we will focus on in this article with the help of BP Automotive owner Bill Hillock.

What you need to know

Before ordering a belt for your project, you need to know some information about your engine and gearbox. For example, if you can tell the year of the drivetrain, whether it is drive-by-wire or drive-by-cable, what injectors you have, whether it is generation III or generation IV, etc. this will be very helpful in kit order. And while GM has done a great job with the modularity of the 3rd and 4th generation LS engines, there are a few differences between them that need to be identified to ensure you choose the right one. But don't worry if you don't know all the answers because we dodetailed articlewhich allows you to search for any information.

Total

we visitedBP Automotive websiteand ordered a Gen III Drive-by-Cable engine control kit for the Suburban. Unique to this system is an independent custom wiring harness, pre-programmed GM Power Control Module (PCM), PCM Socket, Delphi Mass Flow (MAF) Sensor and two Delco AC Oxygen Sensors. With this package we got everything we needed without having to go to the auto parts store at the last minute.

Our package arrived within a few days of placing the order. We were happy to unpack it and check the harness. The first thing we noticed about BP products is that each thread has a label. Then we remembered that we had chosen a braiding loom with a stopper, and it was worth the $75 upgrade. This nylon mesh loom looks and feels much better than the plastic loom used in most standalone devices. We also received a very detailed manual and a document stating that the harness passed quality control along with the harness, sensors and PCM. And while the strap looks very nice, there's more to it than just looks.

Hillock said: “Our harnesses are manufactured entirely in-house, giving us full control over the quality of our product. We only use TXL cross-linked wire to OEM standards and terminate connections with specialized hand tools and other manufacturing equipment. All BP Automotive belts are computer tested to ensure no human error. So we know that if we have a starting problem, it's on our side, not BP Automotive.

let's start

Technically, you can install a standalone wiring harness while the engine and transmission are in the vehicle, but we do not recommend this method. In our opinion, it is much better to carry out the replacement as complete as possible before starting the installation process. Items such as manifolds, exhaust pipes, oxygen sensor location, and even mass air flow (MAF) sensor location can determine the routing of some wiring. And while we love working on vehicles, going back and re-routing is never welcome.

When we started this project, the replacement was a '91 Suburban. it was about 95 percent complete. The fuel system was hooked up, the radiator and fans were fitted, the exhaust system was fitted, even the engine had all the trim including the ignition coils and intake manifold. So there is only one thing left for us to do, and that is to fasten our seat belts. But take your time. Hillock said: "People are excited, they take the strap out of the box and try to fit it right away. Slow down, familiarize yourself with the seat belt, then read the instructions. Content is your friend, and the manuals answer 99 percent of the questions we receive."

PCM installation

We usually prefer to mount the PCM in the vehicle. They can usually be placed behind the dashboard or under the driver or passenger seat to hide the unsightly device. However, Suburban fought with us for this idea. Behind the control panel there was no space due to ventilation ducts, and shell sockets also did not provide enough space for the device. Our only option was to mount it in the engine bay. We set out to find the perfect spot for the PCM in the GM mount around the engine bay, but we had one problem: the PCM mount needs to be on a flat surface, and despite the Squarebody's square exterior, the engine bay is quite round.

Ironically, finding a home for PCM was the hardest part of the process. To get an idea of ​​where we could mount the PCM, we routed the wiring harness in the engine bay. Unfortunately, the passenger side fell off due to the battery and air conditioning. We also looked at the radiator bracket, but couldn't because the light plugs were sticking out, leaving us with only one option - the area in front of the driver's side wheel arch.

We recreated the PCM in a new location and made sure we had enough space to put the stripes where they needed to be before we drilled holes in the inner fender, making it durable. It is worth noting that the PCM carrier is plastic; Although some aftermarket companies offer metal brackets, GM always uses a plastic bracket to ensure that the PCM is connected to the intended source and not to the chassis, which can cause problems.

Plug it in

After installing the PCM and fuse block, we turned our attention to the wiring harness. BP Automotive simplifies the installation process by labeling each wire. The only thing that can cause confusion is the wires labeled "Bank 1" and "Bank 2". Row 1 refers to the driver's side of the engine, while row 2 refers to the passenger side. Each group has a coil connector that connects to the coil pack and four fuel injection connectors on each side of the engine.

After sorting out banks one and two and connecting them to the coils and injectors, we proceeded to attach the idle air control (IAC) valve and throttle position sensor (TPS) to the throttle body. We then fitted two grounding points to the rear of the driver's side cylinder head and connected the knock and camshaft position sensors to the rear of the engine. Next, we routed the power cord connected to the starter motor, the oxygen sensor wires, and the crankshaft position sensor wire along the top of the gearbox, making sure to keep them away from the manifold.

The only other wires that need to be connected are the transmission wires and air conditioning wires. We ran the transmission wires through the tunnel to clear the outlet and connections. Next, we connected the transmission connector and the speed input and output wires. If you have a 4L80e or 4L60e with a transfer case, you will need longer wires to the input speed sensor as the output sensor is in the transfer case. Luckily, BP had an extension cord that allowed us to connect the output speed sensor in the transfer case, so we didn't have to cut wires. And if you need something special, such as longer cables or re-routing, let the manufacturer know before ordering.

“Because we manufacture the tires in-house, we can adapt the design to the customer's needs if necessary,” explains Bill. The only exception is a change to where the "trunk" of the wiring harness exits the passenger side engine. We still reverse mount the 4150 style throttle body and intake manifold bands. We can add housings for ethanol content sensors and other sensor displacements. Just send us an e-mail and we will easily give you a price and delivery time. Custom requests usually require an email to ensure we know your specifications.

Air conditioning

The factory ECU needs a signal from the high pressure line when the A/C system is on to keep the engine idling and turning on the cooling fan. In our application, we used an aluminum welded joint from BP Automotives and a GM pressure sensor. BP also offers other types of connectors and products to facilitate the installation process. However, it is very important that this part is in place for the system to function properly.

Coolant and oil pressure sensors

The BP wiring harness does not come standard with a factory oil pressure sending module connector, but you can ask the company to add one if needed. In most cases, the oil pan is used as a transport unit for factory or aftermarket gauges. But if you have a set likeDigital Dakotagauge with an OBD II/Can interface module, consider adding the oil pressure wires back to the wiring harness. Since the OBDII/CAN interface takes data from the OBDII port to display gauges, adding wires means less running to the cab. The same applies to the coolant sensor. Since we are using Dakota Digital gauges and OBDII/CAN interface, we do not need to add an additional water temperature sensor to the mixture as the wiring harness has it. However, this is not a problem, as there is a plug above the head on the passenger side that can be removed and replaced, allowing the connection of two temperature sensors.

Mass air flow sensorR

The MAF (MAF) sensor wires are quite long, which allows plenty of room to route the wires to the sensor. However, they are aimed at the other (passenger) side of the engine. Since the battery in our truck is on the passenger side, we were forced to move the battery or throw out the air filter on the driver's side. In retrospect, we should have informed BP of this and they could have made this adjustment for us. The problem is that the wires are dangerously close to the poly V-belt, which can cause problems on the road if we are not careful.

Party packages

Until now, our harness was simply plug and play. But you have several wires to connect, labeled bundles 1, 2 and 3. Keep in mind that we like to use non-insulated connectors and heat shrink tubing to connect wires. This method ensures a strong and visible connection, and the adhesive contained in the heat-shrinkable layer protects against moisture. But you can use insulated connectors or solder to get the job done. Just take your time and make sure everything is ready before cutting and connecting the wires.

package one

Package one contains a two-wire connector that will start our engine. Two ignition circuits and fuel pump have been replaced. Since there is already a fuel pump relay in the fuse box, we only had to connect one wire. We found the existing fuel pump wire in the engine bay and connected it together.

Next on our list was the ignition wire, which we routed through the cabin. Switch ignition means that no current flows through the wire until the ignition switch is turned to the "on" or "run" position. This wire in the factory wiring harness can be easily found by the indicator light. Once we found the right one, we connected it to the pink/black wire in the BP harness.

Package two

Bundle 2 consists of four wires for electric fans. The BP manuals contain a diagram showing how to connect them in a configuration with one or two fans. In addition, one or two relays are needed, depending on the chosen route. We used two GC Cooling fans and their relays and wiring harnesses, then spliced ​​the BP wiring harnesses together for a clean install. BP also offers its own set of relays color coded to match the wires in the wiring harness for easy connection.

Package three

The third bundle has the most wires and all of them should be in the vehicle. Since our ECM was mounted in the engine bay, we decided to unhook the OBDII module to route the cable through the stock grommet in the firewall. Of course, we could have drilled a larger hole, but we prefer to use an existing hole where possible. If you plan to disconnect the OBDII port, be sure to label the wires and their location. This is extremely important and can cause serious problems if done incorrectly. Fortunately, the connector has numbers to make the process easier.

After reassembling the OBDII port inside the truck, we routed the rest of the wiring to the cab. This wiring kit includes tachograph output, speedometer, fault indicator and brake switch. The cable for tachograph and speed is simple, because it is connected to the inputs of electronic counters. The fault indicator wires connect to the check engine light so you'll be notified if the ECU detects a problem. However, if you try to use an LED bulb, it will always stay on and you will need to connect a resistor to make it work properly. BP offers resistance if you need it, which we did.

The last item to connect in kit 3 is the TCC/brake switch required for the 4L60 and 4L80 transmissions. This switch tells the ECU when the brake is applied so it knows to unlock the torque converter. We used part number TCC-001 and replaced the square brake switch on the body. This switch has two sets of connections: one for the brake lights and one for the ECU.

Get ready for a mess

We spent several hours on this installation and now our vehicle is ready to start. However, since it has a camshaft, heads and larger injectors, we still need a little more tuning before it's ready to hit the road, but the LS swap is 100 percent complete.

When you are ready to install a new belt, we recommend that you read all the instructions. This will save you a lot of time and possibly headache during the process and you won't have to think too much about it. "Although it may seem too simple or something is missing, the installation of the BP Automotive belt is extremely easy," said Hillock.

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