Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website. 45 Introduction Underneath all of the electronic devices on a modern engine are mechanical parts that would be recognized by a technician from 100 years ago. Before assuming that a problem is in one of the high-tech areas of the vehicle, it is often necessary to use one of the tests covered in this project to eliminate the engine’s internal parts as the source of problems. It is almost impossible to service modern vehicles without knowing how to use a scan tool. Every vehicle system is controlled by, or sends input to, the onboard computer. This information can only be accessed with a scan tool. Even if a problem is in a system not monitored by the onboard diagnostics, the scan tool can still be useful in helping the technician narrow the field of possible causes. In the following jobs, you will test engine components and interpret test results. You will perform a vacuum test and power balance test in Job 8. In Job 9, you will test check engine compression and cylinder leakage. In Job 10, you will check engine oil pressure. You will use a scan tool to retrieve diagnostic trouble codes in Job 11. Project 4 Jobs • Job 8—Perform a Vacuum Test and a Power Balance Test • Job 9—Perform a Cranking Compression Test, Running Compression Test, and a Cylinder Leakage Test • Job 10—Perform an Oil Pressure Test • Job 11—Verify Warning Indicator Operation and Retrieve Trouble Codes Project Diagnosing Engine Problems 4