Article > Tech

OE or Aftermarket?

By Gary Goms

Ever wonder what goes through your professional customer's mind when he's sourcing electronics? Here's one shop owner's perspective on why he prefers aftermarket over OE.


One component segment that's growing faster than any other segment in the aftermarket parts market is automotive electronics. The reason is that most new vehicles are now being delivered with electronically controlled body, chassis and powertrain systems, not to mention a potential array of space-age electronics, including drive-by-wire throttle systems, electronic valve timing, electronic braking, electronic power steering, and a full menu of electronic entertainment and collision-avoidance systems.

You say, for example, that your automatic transfer case doesn't shift into four-wheel drive on your new SUV? The problem often lies, not with the mechanical parts, but with the vehicle's chassis electronics. And let's say we have a failed rear windshield wiper on a minivan. No, the technician doesn't diagnose the problem with a screwdriver and a test light. Instead, he attaches a computer scanning tool to the vehicle's 16-pin data link connector (DLC) in order to verify the operation of the body control computer, switches and motor.


For a better perspective on the increasing importance of solid-state electronics in modern vehicle operating systems, let's first recall that in 1974, Chrysler Corporation introduced the electronic ignition as standard equipment on all of its passenger car and light truck vehicles. In 1982, General Motors introduced its C-3 computerized electronic engine control system as standard equipment on its passenger car line. During the late 1990s, Ford began using a general electronics module (GEM) to control powertrain and non-powertrain functions in the vehicle body and chassis. As a matter of fact, since 1996, many auto manufacturers began integrating various functions of the engine, automatic transmission, transfer case, anti-lock brake, air conditioning and charging systems into a single system known as multiplex electronics.


What is a multiplex system? First, each vehicle accessory in a conventional system has its own control wire or wires. But when we add options like a safety-controlled rear hatch door complete with redundant lock sensors, interior lighting controls, defroster grid and rear wiper operating system, we're increasing the wiring bundle size far beyond the ability of the average chassis to accommodate it. Multiplex systems, on the other hand, reduce wiring bundle size by allowing various electronic modules located throughout the vehicle chassis to communicate with each other through a single wire.

Imagine multiplexing as a sophisticated communications system in which wiring bundle size is reduced by using a single control wire to operate multiple accessories like interior lights and power door locks. To do this, multiplexing uses a central body control computer to communicate with accessory control modules or nodes by sending a coded message along the communications wire. Obviously, multiplexing calls for high-speed computing in order to send, receive and prioritize all of the messages sent and received on the communications line. Prioritization means that safety-related messages might, for example, take priority over all other messages. In more concrete terms, this means that the body computer will lock the doors before it turns on the air conditioning.


Automotive electronics has always been the 800-pound gorilla lurking in the aftermarket closet. For example, during the auto manufacturer's typical three-year or 36,000-mile warranty, the aftermarket has little opportunity to develop failure rate or lost-sale histories, create product supply channels or place the electronic product on jobber shelves. The first three non-warranty years, on the other hand, may be spent developing sales histories, creating product and installing inventory. Even at that, now-inventoried parts might strike out in sales because the projected failure rate might be modified by a warranty replacement of the part itself by the OEM supplier.

Obviously, tooling to make an electronic part can be a high-risk investment for an aftermarket manufacturer. Nevertheless, the risks are high, the stakes are huge and the market can only become exponentially more intense as the passenger car fleet continues to age.


Quite clearly, the original equipment manufacturer will be the primary source for electronic parts during the first few years of post-warranty operation. After that point, the independent shop operator wants the convenience of buying from his local jobber store, so the aftermarket has responded in the past by designing and manufacturing an OEM-equivalent replacement or outsourcing from an OEM supplier.

In today's world, however, many electronic components, such as the nodes or modules that allow the component to communicate with the body control module, will contain logic chips that contain encoded proprietary information. To make issues even more complicated, many of these nodes or modules must be flashed with the vehicle VIN before installation so that they can communicate with the body control module. Consequently, designing a modern replacement wiper motor assembly isn't as simple for the aftermarket because the issue of OEM intellectual property rights of logic-based electronic parts becomes involved in the manufacturing process.

Both issues are currently a point of contention between the OEM manufacturers and the aftermarket parts industry, with the OEMs claiming rights of design and the aftermarket claiming rights to fair competition in the electronic parts market. No matter where the various legislative proposals will go, their final disposition will nevertheless greatly affect the ability of the aftermarket parts industry to manufacture logic-based electronic parts.


Obviously, the confluence of the above issues occurs in the aftermarket repair shop. The two basic reasons why most operators buy OEM parts are a lack of availability or lack of competitive pricing in the aftermarket. The two basic reasons most don't like buying OEM parts are limited warranties and the possibility that the part can't be returned.

To illustrate, I have a 1988 Chevrolet Camaro in my shop at this very moment that defines the OEM/aftermarket issue in real-world terms. To begin with, this Chevy has suffered a series of mass air flow (MAF) sensor failures. Currently, the vehicle is on its third remanufactured MAF sensor, with the last sensor failing one year after installation date. The first MAF sensor was defective out of the box, so a warranty replacement was made on the spot.

The early 1980s General Motors MAF sensors had a high failure rate, primarily because they were the first of their kind, and GM, like many other manufacturers, had to establish a learning curve in manufacturing a reliable product. However, if I had bought a new MAF from General Motors, it would have cost twice as much, and the warranty would have terminated with finality only one year later. Of course, the new sensor might not have failed. But, even though the third reman MAF failed on this vehicle, my jobber continues to warranty the part, no questions asked.

Recently, this same vehicle also suffered an ECM failure. But after replacing the ECM with a reman unit, I still had the same driveability issue - a rolling idle condition. Fortunately, my jobber's ignition supplier has a technical hotline with the company that remanufactured the ECM. After working through the data with a tech rep, the rep confirmed my diagnosis of a bad ECM.

So, with the benefits of a liberal warranty policy and a good technical hotline, my vote goes to the aftermarket new or remanufactured electronic part. The warranty benefit goes a long way to reduce any customer relations problems that a shop might have with the product or service.

Given the current trend, the net worth of a vehicle's electronics package will exceed that of its mechanical components in just a few short years. Consequently, the aftermarket must gear up for increased electronics part sales and may also need to gear up for re-flashing modules for specific VIN applications. The future, indeed, does have its challenges, but it also holds the potential for increased marketing opportunities in electronic replacement parts.

Note: In the July issue, Counterman will address flash technology and the opportunities it presents to parts stores.

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