Being dumb about a particular subject is nothing to be ashamed of because we are all dumb to a great many things. Even auto/truck repair mechanics & technicians are stumped by certain mechanical malfunctions that happen to vehicles. Anyone who doesn't agree is just plain stupid. As a part of daily learning experiences, auto repair can be both frustrating and rewarding. Not in any way should auto repair be shunned just because you're not fully familar with it, but at the same time you should be aware of several of the in's & out's and do's & do not's of car repair for your personal safety & your vehicle's well being.

We will shortly introduce the book "Vehicle/Equipment Operating Systems & Components, Plus" which will give plenty of insight to car/truck/equipment repair and maintenance. This book, when used in conjunction with a specific repair manual, will hopefully answer many questions a repair manual doesn't answer and give many troubleshooting tips a repair manual doesn't give. For more detailed info about this book click Here.

Another book we offer, "Tire trouble? Handling problems?", covers tire wear diagnosis, wheel alignment, steering, suspensions, frames and other topics on medium/heavy trucks, motorhomes & buses, and is also a good source for unique information if you consider yourself a dummy on these subjects & these vehicles. More detailed info about this book can be found Here.

Over time, we will expand this page to include an overview of most of a car/truck's operating systems, with helpful links (blue text links) to several of our helpful products, other site pages or even external sites. Scroll down now to begin, and bookmark & return to this site later for updates.

Perhaps electrical system malfunctions of modern vehicles is the most daunting of all the possible separate system malfunctions. These days, electrical systems have control over almost every system that makes it possible for the vehicle to operate as it is supposed to.

ECU (electronic control unit), ECM (electronic control module), PCM & onboard computer all really means basically the same thing in regards to most vehicles, and refers to the electronic control unit or module that controls a variety of systems including the engine electrical system, etc. Some vehicles, however, use more than one ECM , ECU or ICU to control various systems or portions of the electrical system such as dash gauges, lights, HVAC system (heater, ventilation, air conditioner), anti skid brakes (usually includes traction control), transmission, various anti theft devices, etc. These seperate systems can be a stand alone system or linked to the main engine controlling computer.

Like previously stated, a separate ECM or ECU can control such separate things as engine, anti skid brakes/traction control/anti skid control, HVAC unit, dash gauges & lights, auto transmission, and more, or, only one ECM can control several or all of these things. On board "computers" are usually very vehicle specific, meaning that a vehicle of the same make, or model in some instances, may or may not exibit or have the same electronic controls or the on board computer might be programmed somewhat differently from one vehicle to the other. Sensors in various locations send signals to the particular controlling ECM or ECU which then sends a command to the appropriate electromechanical device responsible for that particular task.

Troubleshooting ECM or ECU problems is assisted by a variety of devices from multimeters to special test equipment to code readers to laptop computers. Code readers simply read a general trouble code the ECM or ECU is programmed to log when a problem is detected. Laptop computers, with the correct connectors & programming, can test systems and/or pinpoint or help pinpoint the exact causes of the malfunction. Laptops can also perform other tasks such as speedometer speed correction if the speedometer input is ECM controlled, or engine parameter changes, etc. Special test equipment can range widely but can be extremely helpful in the diagnosis of a computer problem, wiring problem or another component failure.

Many code readers are fairly low priced & affordable by the average vehicle owner, but laptop programming & connectors is extremely expensive & usually only available to dealership shops, etc. Code readers come in various forms with the cheapest that causes the trouble code to blink out on the vehicle's check engine light (click here for a low priced code reader similar to this), medium priced code readers that have a digital display of their own and some can perform the tasks of turning off a check engine light or erasing a trouble code. Higher priced commercial shop type code readers have their own digital display that sometimes give more than info than just trouble codes & can also erase the code from the ECU/ECM memory, turn off and erase from memory any check engine lights, etc. Any time a code reader or laptop computer fails to adequately diagnose a problem or in the absence of a laptop's input, special test equipment can be very beneficial to find and repair a problem connected to an on board computer.

Wiring in general should really never be cut, probed, or spliced into. ECM/ECU related wires are especially sensative to these practices, and doing so could result in ECM/ECU failure or a myriad of component failures. For these reasons alone, when installing a high powered stereo & amplifier system or a device such as our Car/Truck Power Inverter, one should really install a relay kit as described in the book "Vehicle/Equipment Operating Systems & Components, Plus". These such devices should never be tied directly to any wires the onboard computer computer uses for input or output including ground wires. To be sure of any connections to these devices, one really should use power directly from the battery and ground it directly to the battery negative post or directly to a good chassis ground using seperate wires altogether.

See also: Free relay info on our forum page or on our blog at http://hastprotruckscom.blogspot.com (see Blog Archive "2008")

For many years, people (including mechanics) primarily used a test light to test 12v electrical systems. A better, safer way is to use a volt/ohm meter (multimeter, multitester). Preferably a digital volt/ohm meter for certain ECU/ECM/PCM testing, but a cheaper priced analog multimeter or mulitester works just fine for general use & for some ECM/ECU applications. A test light can break the strands of the wire when they are used to probe through the insulation. On wires related to an ECM/ECU/PCM, breaking the strands of the wire changes the resistance of the wire & adversly affects the ECM/ECU performance. Volt/ohm meters read out specific voltages & ohms resistance, which test lights do not, and specific voltages or ohms resistance is very important in troubleshooting modern vehicle's electrical systems.

Ordinary straight pins can be used to pierce wire insulation for volt/ohm meter testing and optional probe clips can also be purchased for the volt/ohm meter. The use of straight pins to pierce the insulation assures that the wire strands will not likely be broken which compromises the integrity of the wire (very very important on ECU/ECM/PCM related wires). When the straight pins are removed, wrap a little electrical tape around the wire at the pierced locations to prevent corrosion or one can use a dab of RTV silicone on the holes.