Giammalvo Files
Mark Giammalvo

Mark Giammalvo specializes in driveability diagnostics at his family business, Sam Giammalvo's Auto Sales & Service, Inc. in New Bedford, MA.   

Mark, who has been with the business for over 20 years, is an ASE  Master Technician and Parts Specialist. He also holds the ASE L1 certification, and has an associates degree in business management.
Mark is also a writer for Motor Age Magazine and is the past secretary of the Alliance of Automotive Service Professionals, (AASP).

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  "The Continuing Mystery of
Solid State Controls"

(Printed in the Journal of The Alliance of Automotive Service Providers, AASP) 

Why are cars such a mystery today? Why have “advances” in technology made cars more difficult to diagnose and repair?

I don't have any one magic bullet answer, but lack of service information is perhaps the greatest issue. The problem lies in the lack of information regarding vehicles' on-board electronic control systems, or, what used to be called, "solid-state" controls.

Look up solid-state in a dictionary, and you will find an interesting definition. It usually says something like, “electronic devices, like transistors or crystals, that control current without the use of moving parts, heated filaments or vacuum gaps.”

Although a term from the 1960s, every computer module today is still a solid-state device. To many, solid-state is any box with attached wiring that has an internal circuit board. It is the box where the magic happens – the box where electronic decisions are made. It is the box with the sticker that says, "Do not open. No user serviceable parts inside."

Automotive technicians today are expected to quickly test, diagnose and repair these solid-state devices. Unfortunately, only a small amount of information is offered about these devices on modern-day automobiles. If were lucky, the auto manufacturer will offer a printed wiring diagram to aid in testing. If we are really lucky, the wiring diagram's wire colors will actually match the colors of the wires on the car we are testing.

All too often, the wiring diagram for the car doesn’t match the colors of the car's wiring. At that point the technician is, in essence, blindfolded, not knowing which wires are supposed to carry what amount of voltage. Even when access to a correct diagram is available, the logic of the solid-state device is usually unknown. Auto manufacturers rarely print the exact strategy of these devices. Often the manufacturers will lay claim that the actual operational logic is "proprietary information." Today’s medical industry faces similar challenges. Often,  pharmaceutical advertisements and literature will state that a medicines “method of action is unknown.” Just like automotive electronics, there is a vacuum or black hole in the information. How then can a technician repair a device when he or she does not know how it operates?
This is where many shops will have to guess and plug in a new module, which generally cannot be returned.  When faced with this dilemma, some shops will refuse to work on the car altogether. Then the customer is left searching for another shop that will take a stab, guess or "shotgun" repair. Take the following examples that both our shop and Motor Age's Richard McCuistian have recently encountered.

  • A customer with a 1997 Jeep Grand Cherokee has the engine computer replaced to correct a performance problem. The customer comes back the next day stating that the keyless entry transmitter is now inoperative. The service manual advises reprogramming the transmitters through a scan tool connected to the vehicle. After performing this procedure the transmitter is still inoperative. The technician places a call to a diagnostic hotline. Now the Chrysler specialist at the hotline asks if the computer was recently replaced. Guess what the cause of the problem is? The customer had not used the new computer enough. After a new computer is installed in a Grand Cherokee, the keyless entry feature will not be activated until the engine has been started 20 times. Valuable shop time and tools wasted. The technician is left looking like a dummy. Why is this information not in the service manual?

  • A 1998 Dodge Durango comes in with the complaint that the four-wheel-drive (4WD) service light is on. This is strange because the truck is actually a two-wheel-drive (2WD) model. A Chrysler service bulletin is found that addresses the problem. The bulletin states that the problem is caused by a defective Heating/Ventilation/Air Conditioning (HVAC) module. Now the customer pays to have the $265 module replaced, but the 4WD light still remains illuminated. A call to the diagnostic hotline reveals more information: The battery must be disconnected for 30 minutes. Then the new HVAC module has to be configured with a scan tool. During the configuration the technician enables the air temperature display function. Finally, the 4WD light is gone but now one of the dash climate control buttons won't stop flashing. Another call is placed to the diagnostic hotline. First the advisor asks if the air temperature function was enabled during programming. Then the advisor asks if this car has the overhead compass and temperature display. Finally the advisor tells the technician to buy a second HVAC module. Enabling the temperature display on a car without the overhead compass/temperature feature causes this failure. Once enabled it cannot be reversed. Now the shop has to replace the $265 HVAC module for free. Again, how is the technician supposed to know this diagnostic strategy if it is not written down somewhere?

  • A 1988 Buick Century comes in with an overheating problem. A technician drives the vehicle with a scan tool connected to view the computer's datastream. The technician is interested in monitoring the engine cooling temperature reading and the on/off command information for the engine cooling fans. On the road test, the technician notices that when the computer turns on the cooling fans several datastream lines have scrambled unreadable data. This scenario is normally a hallmark symptom of a faulty computer. The computer is replaced, but again the same datastream lines are unreadable when the cooling fans are on. A call to the scan tool manufacturer reveals that the car's computer is fine. The manufacturer's representative advises us that they are aware of this glitch that occurs when their brand scan tool is hooked up to 1988 Buick automobiles. They are going to correct it in a future software update cartridge that we can buy when it’s available.

  • A customer requests another keyless entry transmitter for a ’92 Oldsmobile Cutlass Cieria. The  $99 transmitter is special-ordered. Now the fun part: Try programming it to work with the car. To program a new transmitter, the procedure in the ’92 Cieria service manual says to: 1) Turn the ignition off. 2) Jump together terminals A and B of the Assembly Line Diagnostic Link (ALDL) connector under the left-hand dash. 3) Press unlock on one transmitter. 4) Press unlock on the second transmitter. 5) Disconnect the jumper wire. After trying this procedure six times, the new transmitter still does not work. On a hunch, the technician looks up the same procedure for a 1991 Ciera. The procedure for the 1991 is totally different. That procedure says to: 1) Access the remote entry connector, (green in color), in the trunk under the left rear wheelhouse trim. 2) Put a screwdriver between the two terminals in the connector to join them together. 3) Push any button on the first transmitter. 4) Push any button on the second transmitter. 5) Remove the screwdriver and reseat the trunk trim. It worked on the ’92 Ciera. Nevertheless, why did the technician have to use a 1991 procedure on a 1992 car? Why did the 1992 procedure not work? On what car does the 1992 procedure actually work?

Unfortunately, in the modern world of solid-state controls, some progression will always lead back to some regression.

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