Until an advanced alien species teaches humans how to transmit electricity through the air, without frying everything around it, electrical wiring is here to stay. That's not good news for the hoards of hot rodders that aren't man enough to route simple strands of copper, but companies like Painless Performance have made the process remarkably straightforward. While Painless has built its reputation on quality harnesses, switch panels, and wiring accessories for just about every application imaginable, it has recently developed a new range of products that help muscle car guys enjoy the perks of modern technology. We're talking about new standalone controllers for electronic overdrive transmissions, keyless entry systems, CAN gauge interfaces, and pushbutton ignition start systems. To find out how to hook up this trick new technology to your old-school Bow Tie, we had Dennis Overholser of Painless explain it all to us. Additionally, he offered countless tips on how to avoid common wiring mistakes and rig up a fail-proof electrical system.
Not many people look forward to wiring a car, but doing it right is imperative in terms of reliability and vehicle enjoyment. As with any DIY job, avoiding some common mistakes goes a long way in successfully wiring your project car. "It seems like common sense, but two of the most common errors we see is cutting the wires too short and not supporting the wiring harness adequately throughout the vehicle," Dennis explains. "If you let the wires dangle and don't take the time to tie the wires to firewall or frame, they can work themselves loose over time. Obviously, wires on the floorpan aren't going anywhere, but wires routed in the dash or the inner fenders need to be clamped down every 12-14 inches."
In extreme cases, wiring that's in poor health can lead to fires. In less extreme cases, bad wiring can result in everything from the improper operation of the radio, headlights, and gauges. According to Painless Performance, it's not at all reasonable to expect a wiring harness that's 40-plus years old to operate as if it's still new. "Using old wiring is a ticket to disaster. You have to assess the kind of condition the harness is in," says Dennis. "Exposure to heat, moisture, and salt can considerably reduce the longevity of wiring. Wires that are brittle or dangling can fail at any time. Sometimes the chassis and interior harness in an old car may still be in serviceable condition, but due to heat exposure the wiring inside the engine compartment is a complete disaster and needs replacement."
Poor ground wiring can create all kinds of electrical gremlins, and understanding why requires exploring the basic properties of an electrical system. "Electric current must make a complete circuit by flowing from the positive side of the battery, through the device it's operating, and then back to the negative side of the battery. If it does not make that complete circuit, electricity won't flow, and the device will not operate," Dennis explains. Consequently, the negative side of the electrical system is just as important as the positive side. "The main battery ground should go directly to the engine/transmission assembly for maximum efficiency. The engine should have a ground strap attached to the frame as well as the body. Some people don't use a ground strap between engine and body because they think that the motor mounts will provide adequate ground contact, but they don't. Without proper grounding, the gauges won't read properly and the overall operation of all the electrical circuits may be compromised. Make sure there is good contact, and also make sure the gauges in the dash are properly grounded as well."
To the average hot rodder, wires are wires and they all look the same. In truth, this is a foolish assumption to make, as the quality of material used to wire a car plays a dramatic role in safety, reliability, and the overall performance of the electrical system. "The Society of Automotive Engineers has developed a very strict system of standards for rating wires. Most wire imported from overseas is general purpose, or GPT wire," Dennis explains. This type of wire has a very low melting point and uses plastic insulation. High-strand cross-link wires—such as GXL, SXL, and TXL—have extra abrasion resistance and heat resistance properties. "Instead of using plastic insulation, they rely on a denser compound insulation material that's more like fiberglass. As a result, all XL-grade wiring has a much higher melting point with a temperature rating of -51 degrees to 125 degrees Celsius, which makes it ideal for high-heat areas like the engine compartment. TXL wire meets the exact same temperature rating of GXL and SXL wire, but because of its thin-wall construction it's the lightest and easiest to route throughout the car. That's why Painless Performance uses TXL wire in all of our harnesses."
As with wires, many people think all wiring harnesses are the same. According to Painless Performance, however, a vehicle's wiring harness can be broken down into three categories: the engine harness, the chassis harness, and the interior harness. While most Painless Performance harness are designed for the complete vehicle and include all three sections, certain applications only require a portion of a complete harness. The engine harness controls the engine functions—such as all the engine-related sensors and electronic throttle actuation—as well as most electronic transmission control functions. The chassis harness has circuits for all the headlights, taillights, turn signals, brake lights, horn, radio, A/C and other basic vehicle functions. Finally, the interior harness is usually part of the chassis harness, and it includes circuits for the gauges and indicator lights. The all-in-one nature of a complete vehicle harness can lead to some confusion for engine swappers. Since these applications often already have a chassis and interior harness, Painless Performance offers separate engine harnesses specifically for engine swaps. "All of our engine harnesses are specific to the engine and not the vehicle. This allows an engine, like an LS1, to be installed into almost any vehicle," Dennis explains. "In other words, the same exact engine harness you would use to swap an LS1 into a Camaro can be used to swap and LS1 into a Chevelle. Caution is always advised when transplanting a newer engine into a car that's already computer controlled. Different computers control different functions, like gas gauges, and may not be compatible with the new computer being installed. In these instances, we recommend calling the Painless tech line at 800.423.9696 to prevent potential headaches."
Safely Adding Accessories
Very few muscle cars left the factory with power accessories, but today's enthusiasts want the same level of comfort and convenience in their play cars as they have in their commuter cars. Since adding features like power door locks, power windows, stereos, and even GPS can lead to hacked up wiring, Painless Performance offers several products to ease the wiring process. "Each accessory circuit needs some kind of electrical protection, and it's always advisable to use a separate fuse block or circuit boss to reduce the potential for fire. Painless has several auxiliary fuse blocks, like the CirKit Boss, which are designed for adding circuits to any vehicle," says Dennis. "It includes an in-line circuit breaker, a relay, a fuse block, a pre-terminated wiring harness, and mounting hardware. Another nice feature is that it includes both constant and ignition-actuated hot circuits. If there is a spike in current, the CirKit Boss will overheat the fuse and open the circuit for an extra margin of safety."
Properly wiring high-draw accessories like electric fans requires using a relay, but many hot rodders get cheap or lazy and don't bother running them. However, tapping into an existing circuit instead of using a relay can result in poor accessory performance and compromised reliability. So how do they work and when do you need them? "Relays are high-current switches that are remotely activated. The purpose of a relay is to switch high-current devices like electric fans and lights, thus preventing premature failure of the controlling switch," Dennis explains. "Any device that requires a current load of 10 amps or more should always have a relay in its circuit. A standard toggle switch can only handle 10-15 amps max. That's why toggle switches burn up so quickly when you use them to activate electric fans. By taking the brunt of electrical current, relays designed to switch high-current accessories can handle up to 70 amps."
Screw connectors, soldering, and crimps are common methods of joining wires and terminals together, but they can all work themselves loose. As far as Painless Performance is concerned, for a durable connection it's tough to beat a good crimp. "Most people would think soldering is the way to go, but I am a believer of crimp terminals. If a professional is soldering and using heat shrink, then the joint will last a very long time, but the average person rarely uses a soldering iron correctly and isn't proficient at making good, solid joints," Dennis opines. "When soldering, overheating the copper strands, making cold joints, and causing the copper to get brittle can shorten the life of a joint. A good crimp joint can last forever. A messy solder will create more problems than it solves. Keep in mind that GM does not solder wires and crimps. Another benefit of crimping is that the joints have more flexibility than a solder. To crimp a wire, first strip it to correct length for the terminal it will go into. You should just barely see the copper sticking out the ring or the fork. The terminal should be secured on the wire, but don't squeeze it too hard and mash it up."
Engine Swap Harnesses
Late-model vehicles have very complicated factory wiring systems that can be a bear to work with when swapping a newer EFI motor into a muscle car. Cutting and splicing is par for the course, as is sifting through wiring diagrams to figure out which wires are needed and which ones aren't. Fortunately, opting for a Painless Performance engine harness eliminates the hassle involved with modifying a factory harness in an engine swap application. "Each Painless engine harness is designed for a specific engine and transmission combination. They use all new connectors and wires that have the correct color codes for proper wire identification," Dennis explains. "Additionally, all harnesses have a diagnostic connector and a check engine light. In contrast, a factory harness must be cut and spliced for a proper fit. With a Painless Performance harness, everything you need is there, nothing more, nothing less. Likewise, all wires are pre-terminated to tell you exactly where each one goes."
Race Car Wiring
Race cars don't need to power many accessories, but the accessories they do need—such as electric fans and fuel pumps—draw lots of current. To address these needs, Painless Performance offers many different harnesses, relay kits, and switch panels to properly power various high-current devices. "The first decision to make is identifying the end use of vehicle. Is it going to be a street/strip car or an all-out race car? A street/strip car will use a combination of a switch panel and factory switches, while race cars use switch panels only," says Dennis. "We offer both individual panels as well as a complete fuse/relay block assembly. To simplify the wiring process, all the wires, relays, and fuses are designed for carrying the proper current for each device. All the race car harnesses and switch panels we build are NHRA approved. Generally, you can save about 10 pounds by replacing a factory harness with a race harness."
Electric fans are becoming very common in muscle cars, and the good news is that you don't need a fancy EFI system to control them. Painless offers several standalone fan controllers that help simplify the transition from mechanical to electric fans. "We have several different types of controllers that vary in complexity. A simple thermostat can be used to switch the fan relay on and off at a predetermined temperature," says Dennis. "The more complex controllers are computer controlled and use several sensors for inputs. For instance, a thermostat can trigger the controller to switch the fans on and off and to also help control fan speed as required by engine load. They can also control fan operation when the A/C is on, and at highway speeds. Some of our controllers even use multiple inputs like coolant temperature and vehicle speed to determine when and how fast to run the fans."
New cars may be short on character and cool from the factory, but keyless entry and pushbutton start systems are gizmos any car guy wouldn't mind having on their hot rod. Thanks to Painless Performance, it's not just a pipe dream anymore. The company's new Phantom Key brings OE convenience to older cars. "Adding it to any vehicle is as easy as replacing the existing ignition switch with a new pushbutton and installing the Phantom Key control module," Dennis explains. "Once the system detects when the keyfob is inside the car, just press the brakes and hit the start button to fire up the car. The keyfobs can also be used to lock and unlock the doors, open the trunk, or turn on the dome light."
Electronic Transmission Control
Many muscle car enthusiasts with carbureted engines have shied away from electronic overdrive transmissions because they have no way of controlling them. With Painless Performance's new Perfect Torc standalone transmission controller, that's no longer an issue. Available for 4L60E, 4L65E, 4L80E, and 4L85E transmissions, the Perfect Torc system is a fully programmable controller that uses a throttle position sensor and a vehicle speed sensor to create a shift sequence for the transmission. "Using a laptop and the included software, you can create your own high-performance shift points. The system also features a output that connects to an electronic speedometer," says Dennis.
Gauges Made Easy
When transplanting an LS small-block into an older Bow Tie, the factory EFI system already has sensors that monitor vehicle speed, engine rpm, coolant temperature, oil pressure, and oil temperature. As such, it seems silly to add a second set of redundant sensors just so you can hook them up to aftermarket gauges. Painless Performance felt the same way, which is why it developed the new LS Gauge Control module. "The unit plugs into the diagnostic connector, reads input from the various engine sensors, and then sends those signals to the aftermarket gauges through a CAN network using one of several harnesses we offer. This eliminates the need for duplicate sensors and greatly simplifies the wiring process," Dennis explains.