Chapter 25 Computer System Service 429 Copyright Goodheart-Willcox Co., Inc. Activities 1. Describe and sketch the procedure you would use to test a temperature sensor for proper operation. 2. Demonstrate two methods of checking a knock sensor—with a multimeter and by manual tapping. 3. Look up vehicle software update on the Internet. Try to find which cars sometimes require com- puter reprogramming. Write a paragraph on your findings. Review Questions Answer the following questions using the information provided in this chapter. l. What should you look for during a preliminary inspection of a computer system? 2. Explain five questions you should ask yourself when analyzing computer system problems. 3. How can a vacuum leak upset the operation of a computer system? 4. An engine runs poorly only when cold. Symptoms and a trouble code indicate a problem with the engine coolant temperature sensor. Technician A says to measure the engine coolant temperature sensor’s resistance with a digital ohmmeter while measuring coolant temperature with a digital thermometer. Technician B says to measure the sensor’s ac voltage output while measuring its temperature with a digital thermometer. Who is right? (A) A only. (B) B only. (C) Both A and B. (D) Neither A nor B. 5. How do you check sensor reference voltage? 6. Explain three ways to test an active sensor. 7. Describe three ways to test an actuator. 8. Relays are a common source of problems in a modern computer system. True or false? 9. How do you save computer memory? 10. The computer must be removed from a late-model vehicle. Technician A says to keep one hand on chassis ground when handling the computer. Technician B says to wear an anti-static wrist strap when handling the computer. Who is right? (A) A only. (B) B only. (C) Both A and B. (D) Neither A nor B. ASE-Type Questions 1. Technician A says automotive computer system trouble codes are used to detect faulty compo- nents in the system. Technician B says automo- tive computer system trouble codes are used to indicate the general area of trouble in a computer system. Who is right? (A) A only. (B) B only. (C) Both A and B. (D) Neither A nor B. 2. A trouble code is triggered in an automo- tive computer system. Technician A says fuel-contaminated engine oil could possibly trigger this trouble code. Technician B says fuel-contaminated engine oil has no effect on computer system operation. Who is right? (A) A only. (B) B only. (C) Both A and B. (D) Neither A nor B. 3. Technician A says a basic circuit problem is caused by something in the circuit that increases or de- creases current. Technician B says a basic circuit problem is caused by something in the circuit that increases or decreases resistance. Who is right? (A) A only. (B) B only. (C) Both A and B. (D) Neither A nor B. 4. A scan tool indicates a problem with the MAP sen- sor. Technician A says you should check the op- erating condition of the MAP sensor. Technician B says you should check for poor electrical connec- tions in the system. Who is right? (A) A only. (B) B only. (C) Both A and B. (D) Neither A nor B.