Often misunderstood, always awesome, the turbo is one of the greatest gifts to the automotive world.
At its core, an engine is an air pump, which creates the byproduct of horsepower and torque. A turbo simply increases the engine’s ability and efficiency in regards to moving air in and out of the engine. Rather than relying on the engine’s vacuum to suck air into the engine, a turbo forces the air into the engine.
A turbo has a few basic parts. Two wheels, which resemble fans, are attached to each other with a rod. The fans sit inside housings. The center section resides between the two housings and holds the bearings, as well as the oil journals and the cooling jackets.
A relay, in the most technical terms, is an electro magnet that acts as a switch. As the video shows, when power and ground are applied to the relay, the magnet becomes active, and the switch is completed. The infamous “clicking” one hears when a relay is activated, is the switch being magnetically drawn over to complete the circuit (please see video).
Ok, so a relay completes a circuit when power and ground are applied to it. How can we test if a relay is good in order to diagnose an electrical problem?
Most relays have a diagram of the relay right on the side of them, such as this fine relay here ….
The other day a Nissan came into the shop. The battery and the alternator had been replaced. The car would start if you drove it, and let it sit a few hours, but would need a jump start if left over night. The battery tested good, and the alternator was charging plenty of amps, with no A/C ripple, and 15 volts. Sounds like a classic case of a draw.
I hooked up a test light and found the draw is on the fuse for the alternator charging signal. (For information on how to find a draw please visits here ) Occasionally, you will have an alternator that is charging fine, but back-feeds when the car is off and thus results in a draw. Given the fact that the alternator has already been replaced, it is highly unlikely that the alternator is the cause of the draw. So where do we go from here?
Upon inspection of the alternator, I found the following
When it comes to automotive repair, there are several methods of approaching the problem. Let’s look at: known problems first, maintenance as pair, comprehensive versus fix just what is broken, as well as a few diagnostic approaches.
Known Problems First
Until we correct all the known problems in a system, we can not know if they are effecting the portion of the system we are concerned about. Often times tracking down the cause of one problem will reveal the cause of others. Use this method with a bit of common sense, replacing a gas cap for an evaporative leak will most likely not fix a misfire. However, often times vacuum leaks cause many, many problems. (For a specific example of fix know problems first, visit here )
Every repair order should include the four C’s. The four C’s of automotive repair are, complaint (or concern), cause, correction, confirm. As a technician, utilizing the four c system will ensure you repair a vehicle properly. Similarly, as a customer, looking to see that the four C’s are on your invoice will help ensure you are using a mechanic who knows the proper steps to repairing a vehicle.
We will use the example of a car overheating to demonstrate how to use the four c method. The repair order would say something in the realm of: “Customer states vehicle runs hot, please advise”. As a technician, your first step is to replicate the complaint. Whenever possible, quantify the complaint. Test drive the vehicle and watch the coolant temperature sensor. You can record the data, and add to the repair order, “Test drove vehicle, engine coolant temperature reaches 230 degrees Fahrenheit”.