2Learning ObjectivesExplain the basic functionality of an electronically controlled automatic transmissionDiscuss the functionality of an automated manual transmissionDefine the terms PRNDL, NSBU, VIM, chuff test, differential braking, and ABS modulatorExplain how an air ABS system and traction control operate
3Learning Objectives (continued) Test an ABS wheel sensor circuitDescribe how a fault detected by a trailer ABS ECU causes the trailer ABS warning lamp to illuminate in the truck instrument panelDiscuss the operation of an Eaton electric hybrid systemDiscuss the difference between a series hybrid and parallel hybrid truckList the steps to troubleshoot a wiring problem with the J1939 data link
4Allison World Transmission Currently the most common in North AmericaFull authority control; transmission will only shift when commanded by the transmission ECUWTEC – World Transmission Electronic ControlsElectronic shift control; no hard line to the transmissionTransmission ECU can use information from the J1708/1587 & J1939 data link
5World Transmission Controls Figure 15-2 World transmission components.
7Allison World Transmission (continued) WT Transmissions uses 3 reluctance type speed sensors: engine, turbine, and tail shaftThere are two types of solenoids used: normally open and normally closedAllison Diagnostic Optimized Connection (DOCTM) troubleshooting softwareWT Generation 4 can display diagnostic trouble codes on digital display
10WT Hydraulic Schematic – Third Range Setting Figure 15-9 WT hydraulic schematic – third range attained.
11Automated Manual Transmissions AMT – Automated manual transmissionManual transmission with automatic controlOne or two pedal systemEaton Fuller is currently the most commonDriver interface and transmission ECU communicate via private J1939 network called the EPL
13Automated Manual Transmissions (continued) Primary inputs to ECU are from three transmission mounted speed sensors and rail select and gear select position sensorsEaton AutoShift – Three pedal systemEaton UltraShift – Two pedal systemEaton ServiceRanger™ is a PC-based EST used to diagnose an Eaton AMT
14Eaton AMT Speed Sensors Figure Eaton AMT speed sensors.
15Gear and Rail Select Position Sensors Figure Gear and rail select position sensors.
16Antilock Brake SystemReluctance-type speed sensors on both front and at least two rear wheels on a tandem axle tractorTypical ABS tone wheel has 100 teethThe ABS ECU measures the frequency of the waveform producedABS modulators control air flow to service brake chambers to prevent brake lock upModulators are designed to revert to non-ABS in the event of failure
17ABS Schematic For Straight Truck Figure ABS schematic for straight truck.
18Four Channel ABS With ATC Figure Four-channel ABS with ATC.
19ABS Modulator with Integral Relay Valve Figure Air ABS brake modulator with integral relay valve.
20Antilock Brake System (continued) A chuff test is a brief actuation of the modulation coil at start upA drive axle event can trigger a signal to the transmission and engine ECU or a signal on the J1939 data linkAutomatic traction control (ATC) will limit wheel slip under acceleration
21WARNINGDifferential braking can cause a truck to drive off a jack stand if only one drive axle wheel end is lifted off the ground and the driveline is operated. Traction control must also be disabled if truck is operated on a dyno.
23Advanced Air ABS Sensors Figure Advanced air ABS sensors.
24ABS Warning LampFMVSS 121 requires an amber-colored ABS warning lamp in clear view of the operatorThree methods of controlling ABS warning lamp:Direct control by ECUControl by fail safe relayControlled by J1939 data link with a J1939 multiplexed IPC
26Fail Safe Relay Used to Control ABS Warning Lamp Figure Direct-wired ABS warning lamp.
27Diagnosing ABS Systems Most Meritor-Wabco ABS ECS use warning lamp to retrieve DTCsSome Bendix systems use a blink code switchBendix remote diagnostic unit (RDU) can be plugged into the 9-pin diagnostic connector
28Blink Codes Displayed Using ABS Warning Lamp Figure Blink codes displayed using ABS warning lamp flash sequence.
29Bendix RDUFigure Bendix remote diagnostic unit (RDU).
30Trailer ABSAll trailers built after March 1, 1989 are required to have ABSPower to the trailer ABS is provided through pin 7 of the J560 trailer socketTrucks and trailer built after March 1, 2001 are required to have a trailer ABS warning lamp on ICP of truckPLC – Power line carrier
31PLC Signal Generated by Trailer ABS ECU Figure Power line carrier (PLC) signal generated by trailer ABS ECU.
32Tech TipA problem with the trailer ABS power supply circuit may cause the trailer ABS warning lamps to flash when the service or trailer brakes are applied.
33Hydraulic ABS Systems Required on all trucks built after March 1, 1999 Functions similar to air ABS systemsHydraulic fluid is returned to the reservoir during an ABS event
35Hydraulic ABS Disc Brake Rotor Figure Hydraulic ABS disc brake rotor with cast tone wheel.
36Hydraulic Power Brakes Uses two electric pump motors to charge gas filled accumulators with brake fluid under pressureHCU – Hydraulic compact unitThe HPB system is connected to the J1939 data linkAccumulator pressure is maintained at approximately 2320 psiIf pressure drops below 1523 a low pressure lamp illuminates
37WARNINGNever attempt to drive a vehicle with HPB that has the brake warning lamp illuminated. You may not be able to stop the vehicle.
38Hydraulic Power Brakes (continued) Ignition off, vehicle not moving, service brakes released, unit will go into sleep modeIf ignition is turned on or brake pressed, system will wake and control pump motors as neededSAHR – Spring-applied hydraulically released parking brakeMeritor-WABCO Toolbox™ is the EST used to diagnose the HPB system
39WABCO HPB SAHR Park Brake Figure Wabco HPB spring-apply hydraulic-release (SAHR) park brake.
40Twisted Wiring for ABS Speed Sensors and Modulators Figure Twisted wiring for ABS wheel-speed sensors and modulators.
41Electronic On Board Data Reader (EOBR) Figure Electronic on-board recorder (EOBR).
42Satellite Link Between Truck/Trailer and Fleet Management Figure Satellite link between truck/trailer and fleet management.
43Hybrid Electric Trucks Parallel System – Internal combustion engine is supplemented by electric motorSeries System – Truck is propelled only by electric motor and internal combustion engine charges batteriesA three-phase motor/generator is used to propel vehicle and charge batteriesA battery bank with up to 340V DC power and inverter producing up to 500V AC
44WARNINGLethal voltage levels are used in hybrid electric systems. You should not attempt to work on the high-voltage components of an HEV until you have had proper training and have all of the proper protective equipment including insulated gloves. High-voltage wiring is identified by orange-colored insulation. Never splice into this high-voltage wiring.
45Online Service Information Systems (SYS) Caterpillar Service Information SystemCummins QuickServe OnlineMack Trucks Electrical Information SystemNavistar Service InformationPaccar DAVIE and ServiceNetVolvo IMPACT
46J1939 Bus Type NetworkFigure J1939 bus-type network.
47J1939 Data LinkFigure J1939 data link modeled as a pair of wires with two 120Ω resistors in parallel.
48Damaged J1939Figure Damaged J1939 data link will act as two separate networks.
49SummaryAllison electronic automatic transmissions use three variable reluctance speed sensors to measure engine, turbine, and output speeds. The transmission ECU controls a series of normally open and closed solenoids using PWM. These solenoids control the flow of transmission fluid to apply clutches for specific ranges.
50Summary (continued)Eaton automated manual transmissions (AMTs) use two electric motors to activate the shift mechanism. AMTs are divided into two- and three-pedal systems, indicating if the clutch is controlled by the operator or the transmission ECU. Inputs to the ECU include three speed sensors and rail and gear select positions.
51Summary (continued)Air ABS systems use wheel-speed sensors to determine if a wheel lock up is occurring or is about to occur. The ABS ECU then controls modulators to block air flowing to the brake chambers and exhaust air out of the brake chambers to prevent wheel lock up.Testing wheel-speed sensors and the associated circuits may involve raising each wheel end and rotating the wheel by hand while watching for the amplitude of the AC voltage that is generated by the variable reluctance sensor.
52Summary (continued)Trailer air ABS ECUs on modern trucks use the power line carrier technique to signal the truck or tractor ABS ECS that a trailer ABS fault is active. A variable frequency signal is placed onto the 12V power supply by the trailer ABS ECU. This signal is detected by the truck ABS ECU in its 12V power supply, causing the truck ABS ECU to energize the trailer ABS warning lamp on the truck’s instrument panel.
53Summary (continued)Electronic on-board recorders (EOBRs) are electronic truck operator log books designed to record the hours of service (HOS) for each truck operator.In a parallel hybrid system, a diesel engine and electric motor/generator are coupled together. The electric motor is used to supplement the diesel engine. In a series hybrid system, the electric motor alone is used to propel and the engine is used as a generator for the electric motor. A dual-mode hybrid system acts as a series hybrid system during acceleration and a parallel hybrid system at higher speeds.