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TOYOTA TECHNICAL voltage drop reading (do not crank the engine for more than 10 seconds at a time). 0.2V or less is acceptable resistance. More than 0.2V is excessive resistance. If excessive resistance is found, isolate the cause, repair the fault and re-test the voltage drop. Excessive resistance in this case could be caused by a damaged battery cable, poor connection at the battery and/or starter terminal or poor connection between the starter case and the engine block. MAGNETIC SWITCH This test measures the voltage drop across the starter’s magnetic switch. (NOTE: Starters with planetary gear reduction do not feature a magnetic switch). Connect the meter’s red lead to starter terminal C and connect the meter’s black lead to starter terminal 30. Crank the engine and note the voltage drop (again, do not crank the engine for more than 10 seconds at a time). 0.3V or less is acceptable resistance. More than 0.3V indicates excessive resistance. If resistance is excessive, isolate the cause, repair and re-test. NOTE: A faulty magnetic switch could cause excessive resistance. STARTER CONTROL CIRCUIT Excessive resistance in the starter control circuit can reduce the voltage available to the magnetic switch. Symptoms include nonengagement of the pinion gear and only partial gear engagement. The areas where excessive resistance can occur include the ST contacts of the ignition switch, neutral start switch/clutch start switch and circuit wiring and connections. Test for excessive resistance in the starter control circuit. Connect the meter’s red lead to the positive (+) battery terminal and connect the black lead to terminal 50 on the starter motor. On a vehicle equipped with an automatic transmission, put the shift selector in Park or Neutral. If equipped with a manual transmission, depress the clutch pedal. Crank the engine (do not crank for more than 10 seconds at a time) and note the voltage drop. 1.2V or less is acceptable. More than 1.2V is an indication of excessive resistance. Measure the voltage drop across the ignition switch and the neutral start/clutch switch. 0.1V or less is acceptable. More than 0.1V indicates excessive resistance. If excessive resistance is found, isolate the problem, repair and re-test. As you can see, testing for voltage drop can be a useful diagnostic tool. As mentioned earlier with regard to fl ash reprogramming an ECM, maintaining a steady voltage is critical to avoid ECM damage. An excessive voltage drop can certainly contribute to reprogramming errors and damage to a control unit. This helps to illustrate why use of the GR8 battery station is so helpful, since it maintains a constant 13.5V during fl ash reprogramming. CURRENT FLOW Current is the term used to describe the fl ow of electrons through the circuit. It is this fl ow of electrons that performs the “work” in the circuit. The unit for measuring the amount of current fl ow is the ampere or amp (A). One amp equals 6.28 billion billion electrons per second fl owing through a circuit. Current will only fl ow if there is a complete circuit (continuity) between a source of higher voltage (power) and a lower voltage (ground). Voltage is the pressure that pushes the electrons through the circuit, and Amperes is a measure of the number of electrons fl owing through the circuit. Measured in amps (A) or milliamps (mA), current fl ow is caused when a voltage or pressure differential exists at both ends of a conductor. The combination of amperage with voltage determines the amount of power that is being used at the load in the circuit. Power is measured in watts (W). The amount of power that is being used by a load can be determined by multiplying the amperage through the load by the voltage drop across the load. ★ 12 STAR Service News Spring 2010
STAR Service News BACK ISSUES Issue # Months 25 Fall 1987 27 Spring 1988 28 Summer 1988 29 Fall 1988 30 Winter 1988 31 Spring 1989 32 Summer 1989 33 Fall 1989 34 35 36 38 42 43 45 48 49 60 71 76 82 83 86 Spring 2010 Winter 1990 Spring 1990 Summer 1990 Winter 1991 Winter 1992 Spring 1992 Fall 1992 Summer 1993 Fall 1993 Summer 1996 Jul./Aug. 1998 May/Jun. 1999 May/Jun. 2000 Jul./Aug. 2000 Jan./Feb. 2001 Missed an issue? You’re in luck! The following back issues of the Toyota STAR Service News are available FREE in limited quantities. Use the form to request back issues. Contents Toyota Computer Controlled System Emission Control Systems Air Conditioning Charging & Starting Systems The Variable Venturi Carburetor Toyota Publications Information — Repair Manuals, Collision Manuals, Diagnosis Manuals The Fuel Systems Suspension — Toyota Electronically Modulated Suspension (TEMS)/ 1986 Celica Front Brake System Special Service Tools for Toyota Vehicles/Toyota Engine & Transmission Applications Chart (1981-1989) Free Wheeling Hubs (1984-1988 4WD)/MR2 Cooling System (1985-1989)/ “Y” Series Engines (1984-1989 Van) Security — Toyota Intrusion Monitoring System/Brakes — Toyota Anti-Lock Brake System (ABS)/ Engine (2S-E Engine) 2WD & 4WD Wheel Alignment (1984-1988 Pickup Truck)/Rust Repair Body Repair — Outer Door Panel Replacement/Battery Testing for Winter Camry Timing Belt Inspection & Installation/Four Ways to Control Idle Speed 1988 Camry Automatic Transaxle Description & Troubleshooting 1990 Truck Engine Cooling Systems/22R & 22R-E Engine (4-Cyclinder)/3VZ-E Engine (6-Cyclinder) Diagnosing & Troubleshooting the 1990 Camry Automatic Transmission 1993 Truck Air Conditioning System Engine Short Block Service/Truck Suspension Basics/Automatic Transaxles Cylinder Head Inspection & Service/A/C Diagnostic & Service Tips/ CV Shaft Service Engine Timing Belt/Ride Control/Automatic Transmission Service Engine Knock Sensors/Power Rack & Pinion Steering System Service/ Wheel Bearing Service Wheel Alignment/Cylinder Head Service/Four-Wheel Disc Brake Service STAR Service News 13
Page 1 and 2: Spring 2010 In this issue: Battery
Page 3 and 4: Persistence pays off! I was recentl
Page 5 and 6: BATTERY COMPARISON Diff erences bet
Page 7 and 8: Select MODEL and press the NEXT sof
Page 9 and 10: drawn from the battery under high l
Page 11: STARTER MOTOR CIRCUIT As an example
Page 15 and 16: The 2007 Rav4 (and 2007 Yaris) is e
Page 17 and 18: Like the 2007 Rav4, the 2007 Toyota
Page 19 and 20: While driving, steering eff ort doe
Page 21 and 22: A reciprocal shock absorber system
Page 23 and 24: The shock absorbers are plumbed for
Page 25 and 26: TOYOTA TECHNICAL A height control r
Page 27 and 28: TESTER CONNECTION TESTER CONNECTION
Page 29 and 30: SUSPECTED AREA: • Power source ci
Page 31 and 32: ment and drive new and used car buy
Page 33 and 34: Putnam Toyota Burlingame CA 650-340
Page 35 and 36: Down East Toyota Brewer ME 207-989-
Page 37 and 38: Jim Norton Toyota Tulsa OK 918-254-

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