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Saf-T-Liner HDX Saf-T-Liner EF Minotour Conventional/FS65. Student Guide TBB 2003 Thomas Body PCB Electrical. Course Objectives understanding of printed circuit boards read and understand Thomas schematics identify body harness routing
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Saf-T-Liner HDXSaf-T-Liner EFMinotourConventional/FS65 Student Guide TBB 2003 Thomas Body PCB Electrical
Course Objectives • understanding of printed circuit boards • read and understand Thomas schematics • identify body harness routing • understand chassis-body interface • follow troubleshooting procedure • access service publications and info Thomas Body Electrical TBB2003
Course Content: • 1. Printed Circuit Boards • 2. Battery, Ignition, Ground • 3. Wiring • Understanding Thomas Drawings • 5. School Bus Options • 6. Service Publications • Evaluation • 8. Reference Thomas Body PCB Electrical TBB2003
Section 1 Printed Circuit Boards Thomas Body PCB Electrical
Thomas Body PCB Electrical Minotour Conventional Saf-T-Liner EF Saf-T-Liner HDX Page 1-2
Printed Circuit Boards This electrical system was designed by market, AMPs, and option demand. Make a list of consumers found in every bus ____________________________ ____________________________ ____________________________ ____________________________ ____________________________ it makes sense to control these consumers by the same device and in the same area on every bus Make a list of consumers by market School Transit Chick ________ _________ __________ ________ _________ __________ These consumers would also be controlled by a common device mount in the same area Thomas Body PCB Electrical Page 1-3
Printed Circuit Boards Initial Production Configuration Thomas Body PCB Electrical • Began in production with 2000 model • Type D “New Look” pushers Page 1-4
Printed Circuit Boards Conventional/FS65, Saf-T-Liner HDX Thomas Body PCB Electrical • Conventional/FS65 • new external • access • April, 2003 • New Look Pusher • started 2000 • ER-Transit • MVP-ER • HD • HDX Page 1-5
Printed Circuit Boards MVP-EF Started 2004 Thomas Body PCB Electrical Minotour Started 2005 Page 1-6
Printed Circuit Boards Thomas Body PCB Electrical How many amps is required to provide power to a typical bus body?_________ The rear box pictured above from ER-Transit model Page 1-7
Printed Circuit Boards Thomas Body PCB Electrical • non-conductive platform with printed circuit paths • non-repairable component • Front side of B2 is pictured Page 1-8
Printed Circuit Boards AMP Load Capacity Thomas Body PCB Electrical TBB2003 List examples of circuits for each load: 1 amp ________________________ 5 amp ________________________ 15 amp _______________________ 30 amp _______________________ reference Drawing# 52004770 Page 1-9
Printed Circuit Boards Thomas Body PCB Electrical 4 buss bars for parallel circuits Page 1-10
Printed Circuit Boards How many large cables connect to B1_____ B2_____ Thomas Body PCB Electrical 4 internal buss bars but 2 cables? Page 1-11
Printed Circuit Boards Thomas Body Electrical TBB2003 What is role of diodes D5_________ D6_________ D7_________ Page 1-12
Printed Circuit Boards LED lights Have 1000 ohm Resistors/diodes Why? Thomas Body Electrical TBB2003 Diodes installed Between D6 Ignition & Ground D3 between Switched Power & Ground Where is the bias? See Drawing 52004770 & 52005370 Page 1-13
Printed Circuit Boards Hands-on Activity#1 Thomas Body PCB Electrical LED#29 Relay#3 LED#4 LED#4 tells me___________________________ LED#29 tells me__________________________ Page 1-14
Printed Circuit Boards Hands On Activity#1 using LED lights Complaint: front dome lights are inop Are front dome lights a body or chassis option? ___________ Are front dome lights an option found on all buses or just school buses? ___________ Which PCB will control this option? ___________ Locate the decal on the service compartment door for B#1 What relay controls the front dome lights? ___________ Thomas Body PCB Electrical Page 1-15
Hands-on Activity #2 R&R both PCB Board#1 and #2 What tools are required to remove?______ __________________________________ Remember to firstdisconnect the batteries Thomas Body PCB Electrical Page 1-16
Hands-on Activity#3 You will need a DVOM With the ignition key in the on position Remove P5-B1 and locate circuit LT174 yellow At pin 8 Test the circuit for voltage__________ Disconnect the flasher or flasher fuse at the chassis Test the circuit for voltage__________ Reinstall P5-B1 and flasher fuse and remove P4-B1 Test circuit LT10 yellow for voltage_____ Reinstall P4-B1 and remove P29-B1 Test circuit LT174 yellow for voltage_______ Thomas Body PCB Electrical Page 1-17
Hands-on Activity #4 You will need a DVOM Disconnect P5-B1 and locate circuit LB172 red Test the circuit for voltage__________ Step on the service brake and test voltage See LED#31 amber Re-connect P5-B1 and disconnect P4-B1 Test voltage at pins 3 and 8 red/white wire Depress service brake and test voltage ____ Thomas Body Electrical TBB2003 Page 1-18
Section 2 Battery, Ignition, and Ground Thomas Body PCB Electrical
Hands-on Activity# 5 Battery, Ignition and Ground Thomas Body PCB Electrical Trace the battery cable for the body Where is the body breaker for B1 HDX_________________________ EF__________________________ Conventional_________________ Minotour______________________ Page 2-2
Battery, Ignition and Ground Minotour Thomas Body PCB Electrical GMC Ford Page 2-3
Battery, Ground and Ignition HDX Thomas Body PCB Electrical Battery cable to body from chassis Page 2-4
Battery, Ignition and Ground Saf-T-Liner-EF Thomas Body PCB Electrical Cable routes from solid state breaker on left Frame rail under driver’s seat to B1 Page 2-5
Battery, Ignition and Ground Thomas Body PCB Electrical 61202164 solid state breaker Used on HDX and EF as breaker for battery to body and chassis HDX- mounted on right frame rail just forward of engine compartment EF-mounted to left frame rail below driver’s seat Page 2-6
Battery, Ignition and Ground Body Breaker on Conventional Thomas Body PCB Electrical • located in lower switch cabinet Page 2-7
Battery, Ground, and Ignition Follow the Ground cable from B1 Where does it go? HDX________________________ EF__________________________ CONVENTIONAL______________ MINOTOUR___________________ Using drawing#52004770 and 52005370 Why is there no main ground cable on B2? ______________________________ Locate drawing#52004993 This is a jumper harness from B1 to B2 Follow GND on Pin 1 to ground buss Inside B! and B2 Thomas Body PCB Electrical Page 2-8
Battery, Ignition and Ground Thomas Body PCB Electrical See note B on drawing 52004778 and 52005555 Maximum tightening torque on power connections 65 in-lbs Page 2-9
Battery, Ground and Ignition Shunts Thomas Body PCB Electrical Refer to drawing 52004770 Locate J1 Shunts are non-keyed jumpers Easily changes safety buzzer behavior Page 2-10
Battery, Ground, and Ignition Use drawings 52004770, 52005370 and 52004993 Locate relay#5 on B1 Pin 87 of relay#5 power the ignition buss bar in B1 Follow the ignition/key switch signal from pin 86 of Relay#5 The chassis delivers the key switch signal at P_____ pin______ What powers the ignition buss bar in B2? _________________________________ Locate relay#10 on B2 What circuit connects at pin 86 of relay#10?____ - Thomas Body PCB Electrical Page 2-11
Battery, Ignition and Ground Switched Power See Drawings 52004770 & 52005370 Thomas Body PCB Electrical The school bus market requests an unusual option; at rail road crossings we want to turn off all noise so the driver can hear an on-coming train Noise suppression requires control of specific consumers when the ignition is on Locate the Noise Suppression relay#9 on B1 schematic Like other relays power to pin 30 comes from battery Pin 87 output goes to switched power buss bar Locate the relays controlling defroster fans What powers pin 30?_________________ From P28-B1 pin 4 delivers switched power to B2 B2 noise suppression controls the radio Page 2-12
Section 3 Wiring Thomas Body PCB Electrical
Wiring Thomas Body PCB Electrical • Wire is color coded • Ground wires are white • Wire printed with circuit number Page 3-2
Wiring LW-Warning Light JP-Jumper LD-Light POW-Power from fuse SA-Safety RLY-Relay LB-Brake Light LGT-Output to light LR-Rear Light IGN-Ignition LT-Turn Light GA-Gauge FD-Fan PWR-Power LS-Strobe Light ST-Start MH-Mirror SW-Switch DF-Door DIM-Dimmer LM-Marker Light EL-Headlight GND-Ground AL-Alternator SP-Spare, Speaker AD-Air Dryer IGN-Ignition ICU-Dash BATT-Battery SG-Shielded Ground LP-Panel Light EL-Headlight SW-Switch DRL-Daytime Running * Abbreviation printed on wire and used on electrical drawings/schematics Thomas Body PCB Electrical Example: circuit# 10 is yellow and found in the body harness With prefix I know LT10 is the front & rear left turn lights Page 3-3
Wiring • Each PCB board • has keyed connector • locations on the back • Each PCB board • will have many • of the same number • of connector locations • These connector • locations are • referred to as “J” • the corresponding • harness connector • for each J location • in the back is labeled • “P” or plug • these “J” and “P” • numbers allow you • to locate on the bus • specific circuits shown • in schematics Thomas Body PCB Electrical Page 3-4
Wiring • Pre-made harnesses come color coded from the vendor • This color coding assists in production and service Thomas Body PCB Electrical Where do I install these connections? _______________ _______________ Page 3-5
Wiring Switch Cabinets Thomas Body PCB Electrical • pre-assembled sub components during production • switch base harnesses route to the controlling PCB Page 3-6
Wiring Chassis Interface Connector Thomas Body PCB Electrical Saf-T-Liner EF Page 3-7
Wiring Chassis Interface Connector Minotour / Ford and GMC Thomas Body PCB Electrical J10 interface connector located on left side rear cross-member Page 3-8
Wiring Harness Routing Thomas Body PCB Electrical Body harness Front harness Transition path for harnesses from switch cabinet to body harness HDX, EF and Conventional Page 3-9
Wiring Harness Routing • Minotour • Rear side of • Overhead • Compartment • Interface • harness • main body • harness from • PCBs • switch cabinet • harness • battery cable • to B1 Thomas Body PCB Electrical Page 3-10
Wiring Thomas Body PCB Electrical Body harness routing in left curtain rail for all models What circuits would I find in this harness? ___________________________________________ Where would I find connections to this harness? __________________________________________ What types of electrical failures may I see in the body harness?_________________________________ Page 3-11
Wiring Maintenance • Dos: • inspect wires • repair properly • protect • Don’ts: • damage when testing • make poor repairs • leave loose Thomas Body PCB Electrical Return to manufacture’s standard or improve it Page 3-12
Section 4 Understanding Thomas Drawings Thomas Body PCB Electrical
Understanding Thomas Drawings Drawing Numbers beginning with 5 body Thomas Body PCB Electrical Drawing Numbers beginning with 6 chassis Newest TBB Drawing numbers are 6 digit like 112034 They are sequentially assigned Page 4-2
Understanding Thomas Drawings Types Installation- a visual representation of either the component installation like harness routing or the installed component Assembly- a visual representation of every piece used to make the assembly includes dimensions and part numbers assembly drawing numbers are the part number for the assembly Schematic- a visual representation of the flow of electricity through a specific path including all components used primarily for diagnostic purposes Thomas Body PCB Electrical Page 4-3
Understanding Thomas Drawings Assembly Drawings Using drawing#52005500 Thomas Body PCB Electrical How long is the wire from P34-B2 to the intersection at the left curtain rail?___________ What is the connector part number for P99?________ In P4-B1 what is the pin location for circuit LM12?____ What is circuit SP-2?__________________________ Installation Drawings Using drawing#52006276 How many fasteners must be removed to R&R B2?___ Where is the Weldon flasher mounted?_____________ Are the PCBs mounted per this drawing?____________ Page 4-4
Understanding Thomas Drawings Schematics Use Drawing#52007002 to answer the following questions: Do the dome lights work on battery or ignition?__________ How could I change the board to change the first question? ________________ What PCB controls the dome lights?_________ What Amber LED lit tells me that Relay#4 has power?_____ Where would I look for S3 on circuit LD19 in the bus? _________________________________________ If diode D3 went bad inside B1 what would the driver report?___________________________________ What failure/s would result in front, rear and driver’s dome lights being inop?_______________________________ Thomas Body PCB Electrical Page 4-5