At 615 Lesson 5

How many combinations of zeros and ones are available to an 8-bit computer? 64 128 256 65,536

256

Two technicians are discussing why computers have replaced mechanical control methods for controlling both engine management systems and non-engine systems. Technician A says that computers are able to provide more precise control, faster response, and increased dependability as compared to mechanical methods of control. Technician B says that computers provide the potential to add additional features and functions and also offer increased diagnostic capabilities. Who is correct A only B only Both A and B Neither A nor B

Both A and B

A digital voltage is a voltage signal that does which of the following? It is continuously variable It is continuously variable within a given range and requires time to change. It varies, but not continuously, and requires no time to change. It is often referred to as a square wave. Both B and C

Both B and C

Digital Voltage Signals

Four Types Binary Code or Serial Data Frequency & On-off times fixed (Pulse width modulated) Frequency fixed & on time either long or short (Variable pulse width) Variable Digital Frequency Frequency varies On time remains constant Variable Duty Cycle Frequency constant On time varies Variable Pulse Width Frequency & On time vary

Informational Input Circuits

From other on-board computers via a data bus (serial data signal) Allows input data from one computer to be shared eliminating the need for redundant sensors. From the driver or passengers. A/C Request From the technician Diagnostic trouble codes (DTC) Sensor or output data

Information Processing

Input signals enter the computer through an INTERFACE INTERFACE - has TWO Functions: Protect delicate electronics from high voltage spikes. Converts analog signals to digital signals.

NOT" Gates

Inverter circuit that changes an "on" input signal to an "off" or low output signal

Which of the following components in an engine computer is a volatile memory used by the microprocessor to store temporary information?

RAM

RAM

RANDOM ACESS MEMORY- can be written on, read and erased. VOLATILE RAM- is the type of data that is stored for one run cycle and erased when the key is cycled off. NON-VOLATILE RAM- is memory that is not lost when the power is turned off (digital speedometer) KAM (Keep Alive Memory) memory connected to the battery. Storage of DTC and adaptive strategy.

OR" Gates

Requires one of two "on" signals to produce an output "on" signal

AND" Gates

Requires two "on" signals to produce an output "on" signal

Input Signals

Sensor Circuit Inputs Diagnostic monitor circuits Informational input circuits from other on-board computers Informational input circuits from a driver or passenger Informational input circuits from a technician

Technician A says that the continued changes to automotive design are a challenge to every technician. Technician B says that if you pursue learning through the reading of textbooks, technical journals and through taking technical classes, new technology can become an advantage. Who is correct? A only B only Both A and B Neither A nor B

Both A and B

How Computers Work

They are not an artificial "brain" for the car. They are complicated high speed switching and control devices. Computers use varying voltage signals for input, processing information, and output functions

Logic Gates

Three Basic Types "AND" gate "OR" gate "NOT" gate Gate circuitry consists of transistors wired to convert varying input signals into the desired output. Automotive computers have tens of thousands of logic gates

Voltage Signals

Two Types Analog Signal that changes amplitude over time. (The voltage levels change over time) Digital Signal that has a only one high & one low voltage value. Frequency and on-off time are the only variables.

Concerning an AND gate, which of the following would cause the output(C) to be a binary one?

When both inputs, A & B, are a binary input.

MICROPROCESSOR OPERATION

...

The binary code 01101110 equals what decimal (base-10) numerical value: 5 110 124 421

110

How many combinations of zeros and ones are available to a 16-bit computer?

65, 536

An analog voltage is a voltage signal that does which of the following? A. It is continuously variable within a given range and requires time to change. BIt varies, but not continuously, and requires no time to change. C. It is often referred to as a square wave. D. Both B and C

A. It is continuously variable within a given range and requires time to change.

Which of the following components in an engine computer translates analog input signals to binary code?

A/D converter

RAM-KAM

Adaptive Strategy - Best learned operation to compensate for wear and variation in engines and operator habits. Faults Soft Faults are intermittent faults Hard Faults are currently present faults On-Demand DTC - are current faults found by the ECM performing a self test at the request of the technician. Memory DTC - are DTCs that have been present at some time in the past. Erased after a certain number of key cycles.

Which of the following could cause the reference voltage regulator and the logic gates within a computer to function improperly or not at all? Low battery voltage. Battery does not hold a proper load when the starter motor is engaged. Excessive resistance within the computer's power and/or ground circuits. All of the above

All of the above

Logic Gates In Operation

All three types of gates are used in this circuit. If the ignition key is removed, the headlights are on, and the drivers door is closed, will the chime sound? Why or Why not?

BINARY CODING

BINARY CODING -is made up of a series of OFF-ON pulses. EACH 1 or 0 = 1 BIT 4 BITS = 1 NIBBLE 8 BITS = 1 BYTE Largest Value found in an "8 BIT" computer is 255. OBD II uses a "16 bit" computer.

Technician A says that computerized engine control systems are intended to reduce exhaust emissions. Technician B says that computerized engine control systems are designed to improve fuel mileage and drivability. Who is correct A only B only Both A and B Neither A nor B

Both A and B

Circuit Characteristics C

Bulb 1 will not light. Both sides of the bulb are hooked to power. Bulb 2 will be the brightest. The current flow for bulb 3 must first pass through bulb 2, increasing the resistance and thus decreasing current flow through bulb 3. Bulb 2 has a direct path to ground.

Circuit Characteristics E

Bulb 3 will be the brightest. Bulbs 1& 2 as well as bulbs 4 & 5 are wired in series, increasing the resistance in that part of the circuit. Bulb 3 has a direct path to both sides of the battery.

Circuit Characteristics B

Bulb 4 will be the brightest Bulbs 1& 3, 1&2 wired in series will have higher resistance than the single bulb 4. Bulb 4 will have the highest amperage flow through it.

Circuit Characteristics A

Bulb 4 will not light Both sides of the bulb are grounded Bulb 1 would be the brightest. All the amperage flowing in the circuit must pass through bulb 1. The amperage is split between bulbs 2 & 3.

Circuit Characteristics D

Bulbs 1, 2 & 3 will not light. Both sides of all the bulbs are hooked to power. Bulb 4 will be the brightest. Current follows the path of least resistance around bulbs 1,2 & 3 to power bulb 4

MICROPROCESSOR

CPU has no internal memory. All calculations are completed using data stored in memories. MEMORIES- ROM - Read Only Memory PROM - Programmed Read Only Memory EEPROM-Electronically Erasable Programmed Read Only Memory RAM - Random Access Memory KAM - Keep Alive Memory

Which one of the following components in an engine computer is a nonvolatile memory that contains information specific to a particular vehicle or model?

PROM

ROM

PROM - found on GM vehicles. Contains information related to calibration and special instructions. (removable) EPROM - (Erasable Programmable Read Only Memory) found on OBD II vehicles. It can be erase and reprogrammed by use of a terminal and the scan tool.

Serial Data Signals

Pulse Width Modulated (PWM) Note constant frequency & fixed pulse width

ROM

THREE TYPES OF INFORMATION: Basic Mathematics Instructions - for processing data. Engine Calibration - Data on displacement, number of cylinders, fuel system, compression ratio, transmission, rear axle ratio, tire size, vehicle weight and accessories. Variable Data - Engine speed, coolant temperature, intake air flow, fuel metering, manifold pressure, throttle opening and other engine data. Directions to operate the engine.

OUTPUTS

The actuators, solenoids and relays which are controlled by the computer are powered by BATTERY VOLTAGE. To cause these units to operate, the computer provides the GROUND! Grounds are provided by Transistors called "drivers". Quad-drivers are 4 transistors in a common solid state device. (Film on Quad-drivers) Ground side vs. Power side switchin

Baud Rate

The frequency of the bits (0's &1's) in the binary code is known as the "Baud Rate" Expressed as bites per Second Early GM computers = 160 b/s Mid to late '90s GM & Chrys. = 10,400 b/s Ford = 41,600 b/s Newer Vehicles = 1 Mb/s - 10 Mb/s