TM-9-2320-209-20-2-1 Troubleshooting Part 1 for M44A1 and M44A2 Series Trucks
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TM 9-2320-209-20-2-1 CHAPTER 7 SAMPLE TROUBLESHOOTING PROCEDURE 7-1. GENERAL. This chapter gives sample troubleshooting procedures. The purpose of the sample procedures is to help you see how detailed troubleshooting procedures test equipment procedures, and summary troubleshooting procedures are used to find faults in a system. 7-2. SAMPLE DETAILED PROCEDURE. The sample detailed procedure given is the fuel system troubleshooting procedure for the symptom, ENGINE CRANKS BUT DOES NOT START. This symptom is one you will have when you try to start your truck and certain parts on the truck are not working correctly. In each numbered box, instructions are given which tell you what to do, and how to do it. A large dot is placed next to the “what to do” instructions, and small dots next to the “how to do it” instructions a.Box number gives general instructions on getting the truck ready before you start to troubleshoot. b. Box number gives fault isolation test instructions. In this case you are told to check flame heater fuel lines, and then all fuel lines and fittings. To help you find the flame heater fuel lines that you must check, you are told to see figure 15-1, given in chapter 15. Figure 15-1 is a support diagram that gives you a detailed picture of the fuel lines. The right way to check fuel lines is given in figure 16-4, in chapter 16. The fuel lines and fittings checks tell you what you must look for to decide if there is a problem in the fuel lines. These support diagrams and tests, or checks, are often referred to in detailed troubleshooting procedures to help you find the problem and fix it. After you do the tests you read the question at the bottom of box number If the fuel lines are leaking, the answer to the question is , so you go to the next box. c. Box number gives you a corrective action. In this case the fault is either loose fittings or bent, broken, or cracked fuel lines. The corrective action is what you do to fix the fault, which is to tighten the loose fittings, or replace the bad fuel lines. If the engine still doesn't start after you do this, it could mean that there are other faults in the fuel system besides loose fittings or cracked fuel lines. When this happens, go back to the beginning of the procedure and do each step again until you find the other faults. d. Sometimes the corrective actions given for a fault will tell you what to do to fix the fault, but will not give you detailed instructions on how to fix it. Instead, you will be told to refer to another volume in this manual for these instructions. Box number is an example of this. If the answer to the questions that all the fault isolation test instruction boxes ask is , it means that the symptom cannot be corrected at the organizational level of maintenance. When this happens you are given the instruction “ Tell direct support maintenance. ” 7-3. SAMPLE TEST EQUIPMENT PROCEDURE . The sample test equipment procedure given is the Simpson 160 multimeter dc voltage test. This procedure tells you how to use the multieter to do the voltage tests you will need when you do electrical system troubleshooting. 7-1