AT 121 - Chapter 12 Automotive Starters. Service, Diagnosis, and Inspection – PART BName: _________________________________________Date: __________________________________________WARNING! This lab will have you working with live batteries. Batteries are dangerous devices and can explode if shorted. Fire and explosion can result from carelessness! Batteries also contain sulfuric acid. If skin or eyes come incontact with acid or corrosion on the battery surface flush with water and seek medical assistance!It is important to remember a few things about how a vehicle starts. Most vehicles made after 1990 have a “clutch interlock” switch. This switch prevents a manual transmission vehicle from being starter in gear. However, it is important to make sure that the vehicle is in neutral and the parking brake is set before any type of automotive inspection or service is preformed! To start the vehicle the clutch must be fully depressed. Other vehicles with an automatic transmission must be in either neutral or park in order for the vehicle to start. On most manual transmission vehicles equipped with a clutch interlock the interlock switch is located above the clutch pedal. On mostautomatics the “neutral safety switch” is located on the transmission housing and is controlled by the shifter cable or rod. On Car Starter Motor Inspection – Customer Complaint – “Poor Crank, or Intermittent Crank”If a starter does not run, and the battery checks out, this simple test may be preformed on any vehicle. The test is broken down to inspect the most basic parts of a starter circuit. Proper power and ground must be in the right place at the right time in order for the starter to function when the driver needs it. A Poor Crank means that the starter is functioning and it or the battery may be at fault, however a poor crank could indicate an area of high resistance in the starter circuit or battery wiring. For example, the vehicle may crank slowly, or intermittently. This test checks for areas of high resistance by measuring voltage drop between connections. Before performing this test the battery must be fully inspected and checked!WARNING: When servicing the starter motor or working underhood in the vicinity of the starter motor, note the heavy gauge input lead connected to the starter solenoid is hot at all times. Make sure the protective cap is installed over the terminal and is reinstalled after servicing. SECTION 4 Starter Component Tests - Voltage Drop TestsTools you will need:Given VehicleTool BoardStarter Bypass SwitchDVOM1 - Starter Motor—Motor Feed Circuit Make sure the battery is fully charged, and the ignition is OFF. Disconnect the inertia fuel shut off (IFS) switch. Connect a remote starter switch between the starter solenoid S-pin and the battery positive (+) pin. Connect the DVOM positive lead to the battery positive (+) post. Connect the negative lead to the starter solenoid M-pin. (Shown below) Descriptions1 S-Pin 2 Remote Starter Switch – Bypasses Ignition Switch3 Battery 4 DVOM 5 B-Pin 6 M-Pin 1 Engage the remote starter switch. Read and record the voltage. ________________ Volts (M pin test) The voltage reading should be 0.5 volt or less. If the voltage reading were 0.5 volts or less, you would go to the 2- Starter Motor-Ground Circuit Component Test.If the voltage reading is greater than 0.5 volt, this is an indication of excessive resistance at the connections of the positive battery cable or in the starter solenoid. These areas should be checked, cleaned and torqued to specification. Move the DVOM negative lead to the starter solenoid B-pin and repeat the test. If the voltage reading at the B-pin is lower than 0.5 volts, the concern is either in the connections at the starter solenoid or in the solenoid contacts.Read and record the voltage. ________________ Volts (B pin test)If there was a high voltage drop (greater than 0.5 volts), you should remove the cables from solenoid B-, S- and M-pins and then clean the cables and connections and reinstall the cables to the correct pins. The next step in the repair would be to retest the system if needed. If the voltage drop reading is still greater than 0.5 volts when checked at the M-pin or less than 0.5 volts when checked at the B-pin, the concern is in the solenoid contacts. Install a new starter motor.If the voltage reading taken at the solenoid B-pin is still greater than 0.5 volts after cleaning the cables and connections at the solenoid, the concern is either in the positive (+) battery cable connection or in the positive battery cable itself.Overall Results of Starter Feed Circuit Voltage Drop Test (Pass/Fail/Observations)__________________________________________________________________________________________2 - Starter Motor—Ground CircuitA slow cranking condition can be caused by resistance in the ground or return portion of the cranking circuit.  Connect the DVOM positive lead to the starter motor housing (the connection must be clean and free of rust or grease). Connect the negative lead to the negative (-) battery pin. (Shown Below) Descriptions1 DVOM2 Battery3 S-Pin4 M-Pin5 B-Pin 6 Remote Starter Switch – Bypasses Ignition Switch Engage the remote starter switch and crank the engine.  Read and record the voltage reading. The reading should be 0.2 volts or less.Read and record the voltage. ________________ Volts (Starter Ground Test)If the voltage drop is more than 0.2 volts, clean the negative cable connections at the battery, the body ground connections and the starter ground connection. Retest the system. If the voltage drop is still greater than 0.2 volts, 2install a new cable. If the voltage reading is less than 0.2 volts and the engine still cranks slowly, install a new starter motor.Overall Results of Ground Circuit Voltage Drop Test; (Pass/Fail/Observations)____________________________________________________________________________________________________________________________________________________________________________________QIf at the starter motor feed test, your voltage was 3.4 volts when you tested the positive lead to the battery positive (+) post and the negative lead to the starter solenoid M-pin. What could be the cause? (M pin test)______________________________________________________________________________________If at the next test for starter motor feed, and