1. 1 Automotive Electrical Systems R. Bortignon

2. 2 Electrical System Service & Testing…

3. 3 Testing Fuses 1) test with an ohmmeter set on the low scale1) test with an ohmmeter set on the low scale  should have low/no resistance  be careful checking fuses visually

4. 4 Testing Fuses 2) test with a test light2) test with a test light  the key may have to be in the on position  the control/switch for the circuit may have to be on test light should light up on both sides of the fusetest light should light up on both sides of the fuse if only one side lights up – fuse is openif only one side lights up – fuse is open if neither side lights up – power is not reaching the fuseif neither side lights up – power is not reaching the fuse 1 3 2

5. 5Relays use a low current signal to activate a high current circuituse a low current signal to activate a high current circuit relay coil draws 150mArelay coil draws 150mA contacts can conduct 30-50ampscontacts can conduct 30-50amps

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7. 7 Electrical Faults – High Resistance circuit may not work at allcircuit may not work at all circuit may be dim or work poorly / slowlycircuit may be dim or work poorly / slowly

8. 8 Electrical Faults – Low Resistance  the load’s resistance is partially or totally bypassed  often referred to as a short  causes higher than normal current flow  usually causes fuse to open the circuit frayed wire/bare insulation

9. 9 Light Bulbs bulbs can be single or double filamentbulbs can be single or double filament  double filament = brake light & park light  note the offset indexing pins & 2 contacts  newer style bulbs do not require indexing

10. 10 Testing Bulbs often “blown” bulbs are easily seen during a visual inspectionoften “blown” bulbs are easily seen during a visual inspection sometimes a DVOM will verify the problemsometimes a DVOM will verify the problem  use low resistance setting  polarity doesn’t matter  most bulbs will be ≈ 3Ω to 10Ω  you are looking for…  shorts (low/no Ω)  opens (high Ω)

11. 11 Testing Headlamps older style sealed beamsolder style sealed beams newer halogen, xenon bulbsnewer halogen, xenon bulbs  do not touch the quartz when replacing these! 1 connector is for ground – check for continuity to ground1 connector is for ground – check for continuity to ground 2 nd connector is for hi beam – check for voltage2 nd connector is for hi beam – check for voltage 3 rd connector is low beam – check for voltage3 rd connector is low beam – check for voltage

12. 12 Turn Signals blinking function of the turn signals is controlled by turn signal flasherblinking function of the turn signals is controlled by turn signal flasher may have 1 that controls turn signals & 4 way flashermay have 1 that controls turn signals & 4 way flasher or 2 separate unitsor 2 separate units located in fuse box or under the left side of the dashlocated in fuse box or under the left side of the dash  if one side flashes abnormally fast – check for faulty bulb on that side of the vehicle  if both sides flash incorrectly, the flasher unit may be faulty

13. 13 Reading Wiring Diagrams wire colors – jacket color followed by stripe colorwire colors – jacket color followed by stripe color connectors – identification numbersconnectors – identification numbers usually + side of the circuit up top & ground at the bottomusually + side of the circuit up top & ground at the bottom ground number & locationsground number & locations

14. 14 Using Component Location Function component locator can be used to find connectors, relays, grounds, modules etc.component locator can be used to find connectors, relays, grounds, modules etc. access electrical, then component location in Mitchellaccess electrical, then component location in Mitchell

15. 15 Starter Circuit terminal “B” (battery) is live at all timesterminal “B” (battery) is live at all times terminal “S” (start) feeds power only when the key is in the starting positionterminal “S” (start) feeds power only when the key is in the starting position  “S” terminal will have a neutral safety switch in series for an automatic transmission equipped car  “S” terminal can also have a clutch safety switch in series for a manual transmission equipped car  “S” terminal may have remote starter switch or alarm disabling feature tied into it terminal “M” (motor) has power during cranking onlyterminal “M” (motor) has power during cranking only B S M

16. 16 Starter Solenoid serves same purpose as a relayserves same purpose as a relay is usually mounted directly on the starter motoris usually mounted directly on the starter motor on Fords, it is mounted remotely on the inner fenderon Fords, it is mounted remotely on the inner fender

17. Voltage Drop Test determines if too much voltage is being lost to poor connectionsdetermines if too much voltage is being lost to poor connections voltmeter is set to low voltage scale (0-2v)voltmeter is set to low voltage scale (0-2v) meter leads are placed across a connection (circuit must be turned on during testing)meter leads are placed across a connection (circuit must be turned on during testing) there should not be more than.1v loss per connectionthere should not be more than.1v loss per connection both the positive and ground circuits can be tested this wayboth the positive and ground circuits can be tested this way 17

18. Hey Mr. B can I install… the next 5 slides are helpful when adding electrical accessories to a vehiclethe next 5 slides are helpful when adding electrical accessories to a vehicle 18

19. 19 Adding Accessories you and your students need to carefully consider what’s needed when adding amplifiers, driving lights etc.you and your students need to carefully consider what’s needed when adding amplifiers, driving lights etc. add a relay to an existing circuit so you don’t overload the original circuitadd a relay to an existing circuit so you don’t overload the original circuit

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21. 21 Adding Fuses to Add-on Accessories when adding additional equipment, add a relay to power the circuitwhen adding additional equipment, add a relay to power the circuit calculate the required fuse amperagecalculate the required fuse amperage  eg: 2 fog lights 4Ω each  amperage = 12 volts ÷ 4Ω = 3 amps through each light  3 amps X 2 lights = 6 amps total 6 amps flowing through circuit6 amps flowing through circuit multiply this by 1.5 to allow for any voltage surgesmultiply this by 1.5 to allow for any voltage surges 6 amps X 1.5 = install a 9 amp fuse6 amps X 1.5 = install a 9 amp fuse

22. 22 Hey Mr. B, do you have any wire? determining wire gauge size for add-on circuits…  use a wire gauge table  always better to use a larger gauge size than is required 3'5'7'10'15'20'25' up to 5 amps18 6 16 718 16 818 16 1018 16 1118 16 14 1218 16 14 1518 14 12 18 16 14 12 2018 16 141210

23. 23 Wiring Repair Tips use grommets & loom to protect wires against abrasionuse grommets & loom to protect wires against abrasion crimp & solder, then heat shrinkcrimp & solder, then heat shrink don’t rely on crimp onlydon’t rely on crimp only on air bag systems & circuits to/from computer modules, follow manufacturer’s specific repair instructionson air bag systems & circuits to/from computer modules, follow manufacturer’s specific repair instructions

24. 24 ISO 4 pin & 5 pin relay pin-outs …for your reference 4 pin relay 5 pin relay

25. Additional Resources from the 5050 ShareOut, download the electrical PDF file for your referencefrom the 5050 ShareOut, download the electrical PDF file for your reference 4 short videos have been placed on the 5050 ShareOut folder…4 short videos have been placed on the 5050 ShareOut folder…  voltage drop  electrical faults  measuring current flow  reading wiring diagrams 25