2. OBJECTIVES After studying Chapter 11, the reader should be able to: 1
OBJECTIVES After studying Chapter 11, the reader should be able to: 1. Identify Honda hybrid electric vehicles. 2. Describe how the Honda Integrated Motor Assist (IMA) system works. 3. Explain the precautions necessary when working on Honda hybrid electric vehicles. 4. Describe the features and the operational characteristics of Honda hybrid electric vehicles. 5. Explain the service procedures for Honda hybrid electric vehicles.

3. 2000-2006 Honda Insight The Insight, a two-passenger sports coupe.

4. Honda Civic Hybrid The Civic hybrid utilizes the same Civic body used for the gasoline version.

5. The Civic hybrid uses a specially built 1
The Civic hybrid uses a specially built 1.3-liter, four-cylinder gasoline engine with a chain-driven cam and Honda's VTEC (Variable Valve Timing and Lift Electronic Control) valve train control system. In the Civic hybrid allows three of four cylinders to be deactivated during vehicle deceleration by keeping the valves closed. This process is known as cylinder idling or valve pause. Cylinder idling reduces engine friction and pumping losses in these cylinders and thus aids in regenerative braking.

6. The fuel injectors are turned off to the idled cylinders, but the spark still occurs to ensure the spark plugs do not foul.

7. Torque assist and electric power generation are both accomplished with the Integrated Motor Assist (IMA) motor. The IMA motor is thin and is located between the transmission and ICE.

8. Changes were made for the 2006 model, including a VTEC system called i-VTEC (intelligent VTEC). This system allows the engine to idle on all four cylinders to allow for an all-electric cruise mode, as well as greater regenerative braking action. This system allows the engine to disengage cylinders to improve regenerative braking action.

9. Honda Accord Hybrid The Honda Accord hybrid is a V-6, which provides acceleration faster than a similar nonhybrid version and still provide increased fuel economy.

10. To achieve improved fuel economy, three cylinders (the rear bank of the V-6) are deactivated by closing both valves. This is accomplished using the Variable Cylinder Management (VCM) system which is another variation of VTEC. To reduce the vibration and noise, the V-6 Honda Accord uses two unique features: Active engine mounts. Active noise control (ANC).

11. One new feature on the Honda Accord hybrid is a new air-conditioning compressor that features dual scrolls. One of the scrolls is belt driven while the other has a high-voltage electric drive. During auto stop, the A/C system can now be energized without having to restart the ICE by turning on the electric drive to operate the smaller scroll in the compressor.

12. BODY/INTERIOR FEATURES The dashboards on all Honda hybrids have IMA information, which shows if the system is assisting (batteries being discharged) or charging (batteries being charged).

13. Battery State-of-Charge Indicator
Battery State-of-Charge Indicator. The NiMH battery state-of-charge (SOC) bar graph display represents the current state of IMA battery charge. The indicator is operated by the battery condition monitor module (BCM), which is responsible for calculating the battery state of charge.

14. Upshift-Downshift Indicator. Odometer/Trip Meter/Fuel Efficiency Meter
Upshift-Downshift Indicator. Odometer/Trip Meter/Fuel Efficiency Meter. Engine Status Meter. Idle Stop Indicator. Speedometer.

15. Modes of Operation Vehicle stationary The ICE is turned off and fuel consumption is zero. Startup and acceleration The ICE operates in low-speed valve-timing mode with motor assist. Rapid acceleration The ICE operates in high-speed valve-timing mode with motor assist. Low-speed cruising The valves of all four of the engine's cylinders can be closed and combustion halted; the electric motor alone can power the vehicle. Gentle acceleration and high-speed cruising The engine operating in low-speed valve-timing mode powers the vehicle. Deceleration The valves of all four of the engine's cylinders are closed and combustion is halted. The motor recovers a significant portion of the energy normally lost during deceleration and stores it in the battery.

17. IMA Operation Honda’s hybrid system is known as IMA (Integrated Motor Assist). IMA is a parallel-hybrid configuration that uses a motor-generator located between the ICE and the transmission. All of the electronics for this system are located at the rear of the vehicle, with three power cables running between the IMA motor and the intelligent power unit (IPU).

18. Honda hybrids also use a conventional 12-volt auxiliary starter motor that is used in the following situations: The state of charge of the battery module is too low. The ambient temperature is too high or too low, usually below 0°F or over 115° F. There is a failure of the IMA system and the IMA light is commanded on. A technician has turned off the master switch in the hatch area.

20. Acceleration. During acceleration and other high-load conditions, such as climbing a hill, current from the battery module is converted to alternating current by the MDM (motor drive module) and supplied to the IMA motor, which then functions as a motor.

21. Cruise. When a Honda hybrid is cruising at a constant speed and the battery module state of charge is relatively low, some engine output is used by the IMA motor-generator being operated in generation mode to charge the battery module.

22. During fuel cut mode, the IMA motor-generator is operated in generation mode. In this mode, the IMA motor is driven by the wheels, generating electricity to be stored in the battery module, and slowing the vehicle in the process.

23. There are two deceleration modes: Foot off the throttle, but not on the brake pedal Foot on the brake pedal

24. Idle Stop Mode. When the vehicle speed drops below 19 mph (30 km/h), idle stop mode will typically be triggered, and the gasoline engine will stop turning. The engine will typically remain off until the transmission is put into first to begin accelerating again. Restart is performed using the IMA motor, instantly and silently.

25. Conditions for Engine Shutdown
Conditions for Engine Shutdown. While reducing vehicle speed, the engine stops itself automatically under these conditions: The vehicle speed is less than 19 mph (30 km/h) and the brake pedal is pressed. The transmission is in any gear, except first, before slowing down. The clutch is disengaged or neutral position is now selected. The engine speed is less than 1,000 RPM.

26. Idle stop will not take place during the following conditions: The engine has not yet had time to warm up and achieve closed loop. The transmission is in reverse gear. The battery module is not charged sufficiently to restart the engine using the IMA motor. If the IMA-ECU detects stop-and-go traffic conditions

27. Also, climate control mode will affect whether or not idle stop is performed. When “Auto mode” is selected, the engine will be allowed to continue running to operate the air-conditioning compressor. If “Econ mode” is selected, idle stop may occur, possibly causing the air-conditioning compressor to temporarily stop.

28. Air Conditioning Interaction with Idle Stop Mode
Air Conditioning Interaction with Idle Stop Mode. When the climate control system is set to "Econ" mode, the system will function normally, except that idle stop will only take place if the cabin temperature has stabilized at the set temperature.

30. Conditions for Engine Restart
Conditions for Engine Restart. The engine is restarted when: A gear is selected with the clutch disengaged. The brake pedal is released during deceleration. The accelerator pedal is depressed with the clutch disengaged and/or the transmission’s neutral position is selected. The master brake booster vacuum becomes low. The battery module's remaining charge decreases to a certain level with the clutch disengaged and/or the transmission's neutral position is selected.

31. The Honda Insight was available with two transmissions: A conventional 5-speed manual transmission A continuously variable transaxle (CVT) called Honda Multimatic

32. One of the features of the Honda Multimatic is that it does not use a torque converter, but instead uses a multilayered clutch called a Driven-Shaft-Placed Acceleration Clutch (also known as the start clutch).

34. Gasoline Engine Features The Honda three-cylinder Insight and the four-cylinder Civic use a crankshaft with an axis offset 14 mm, relative to the cylinder-bore axis, so that the crankshaft does not sit directly under the cylinder. Honda claims this reduces internal friction by as much as 3%.

35. NOX Reduction Catalyst System
NOX Reduction Catalyst System. The Honda Insight is designed to operate at a very lean air-fuel ratio during light-throttle cruise conditions. The mixture can be as lean as 23:1 if conditions allow. This provides very good fuel economy, and low HC and CO emissions.

36. LAF (Lean Air Fuel) Sensor
LAF (Lean Air Fuel) Sensor. The Honda Insight and many other Honda engines use a linear air-fuel (LAF) sensor for the primary oxygen sensor that is capable of measuring air-fuel ratios as lean as 23:1.

37. The LAF sensor has two zirconia elements that share a diffusion chamber. There are a total of three chambers: Exhaust flow chamber Diffusion chamber Atmosphere reference chamber

38. The zirconia element that is in contact with the exhaust is the sensor element. The diffusion chamber is the space between the two zirconia elements. By applying varying voltage to the control element, the ECM can control the amount of oxygen in the diffusion chamber. Since the diffusion chamber is the reference chamber for the sensor element, this action changes the output of the sensor element.

40. The LAF sensor can be identified by its five-wire connector: Heater positive Heater ground Sensor element positive Control element positive Sensor element ground

41. High-Voltage Battery Module
High-Voltage Battery Module. The battery pack uses nickel metal hydride (NiMH) technology. The battery pack, sometimes called the battery module, is constructed in a modular form. battery module is only available as a complete assembly.

42. In sealed packages of six cells each, positioned end-to-end
In sealed packages of six cells each, positioned end-to-end. For a total of 120 cells.

43. The cells each have a voltage of 1
The cells each have a voltage of 1.2 volt, and are connected in series for a battery module terminal voltage of 144 volts. The rated capacity of the battery module is 6.5 ampere-hour (Ah), resulting in a storage capacity of kW.

44. The 2006 Honda Civic battery module operates at 158 volts
The 2006 Honda Civic battery module operates at 158 volts. This is achieved by using volt “D” NiMH batteries instead of just 120 cells and 144 volts, as used in most other Honda hybrid electric vehicles.

45. The battery module contains 10 voltage sensors and 4 temperature sensors that send data to the battery condition monitor (BCM).

46. The battery module uses “cabin air” to dissipate the heat produced by the NiMH cells. A two-speed cooling fan is located in front of the battery module and draws air past the NiMH cells to aid in cooling of the high-voltage batteries. An inlet behind the passenger seats is the inlet for cool air.

48. Hybrid Controls Location and Function of Hybrid Components
Hybrid Controls Location and Function of Hybrid Components. The power control unit (PCU) works with the ECU to control the idle stop feature and to regulate the flow of energy between the battery pack and the electric motor. The compartment behind the seats is known as the intelligent power unit (IPU). The IPU compartment contains the following components: The motor control module (MCM). The battery condition module (BCM). The battery module. The battery module cooling fan is located in the right rear of the IPU. The motor drive module (MDM). Heat Sink. DC-DC converter. Power control unit (PCU). PCU cooling fan. Junction board.

51. The IMA Motor

52. The IMA motor serves a number of functions: It assists in vehicle propulsion when needed, allowing the use of a smaller internal combustion engine. It operates as a generator, allowing excess energy (such as during braking) to be used to recharge the IMA battery module, and later to be used to provide assist. It takes the place of the conventional alternator, providing energy that ultimately feeds the conventional 12-volt electrical system. It is used to start the internal combustion engine very quickly and quietly. It is used to dampen crankshaft speed variations, leading to smoother idle. The flywheel retains gear teeth for the backup 12-volt starter motor to mesh with when it is engaged.

53. 12-Volt Battery The 12-volt battery is located under the hood and is a conventional lead-acid design. The 12-volt battery has three functions: 1. Provide power to the onboard computers so that memory is kept alive. 2. Provide a capacitor of sorts for the DC-DC converter that allows for 12 volts of power to be available during idle stop mode. 3. Provide power to the backup 12-volt starter.

54. Normal jump starting procedures can be used, as well as typical charging methods.

55. Electric Power Steering The electric power steering (EPS) system on the Honda hybrid vehicle offers many advantages over conventional hydraulic systems. The pump, hydraulic fluid, and hoses are all eliminated, and because the engine is not constantly driving the pump, power losses are eliminated and fuel economy increases.

56. The EPS consists of a rack-and-pinion gear with a microprocessor-controlled coaxial electric motor assisting the pinion.

57. Auxiliary Heater Pump The Insight does not utilize an electric pump for circulating hot coolant. In cold weather, if the climate control is used, the gasoline engine stays running to provide circulation to the heater core. Later models of the Civic and Accord hybrid utilize “helper pumps” to circulate coolant through the heater core during auto idle stop.

58. SAFETY PROCEDURES Safety Devices Honda hybrids have a computer-controlled system that will disconnect the HV battery pack from the rest of the vehicle in the event of a problem that would allow high voltage to contact anything that was unintended. To accomplish this, the hybrid computer will instantly disconnect the 12-volt power source to the two contactors in the event of an airbag deployment.

59. Disarming the High-Voltage System There are four simple steps to ensuring that the system is safe to work on: Step 1 Remove the ignition key. Step 2 Remove the back seat cushions. Step 3 Remove the two bolts holding the oval cover. Step 4 Remove the red plastic retainer and turn the switch to off; replace the red plastic retainer on the switch.

60. SERVICE FEATURES Unique Spark Plugs The NGK spark plug number ILZFR5A-11 is specially built for the Insight. They are indexed, meaning the ground electrode is positioned for good intake flow.

61. Spark plugs have an A, B, C, or D stamped on the top of each plug that matches up to the markings on the head.

62. How to Depower the Honda HV System Remove the ignition key, then take out the rear seat cushions, and remove a small access panel (one with two bolts – in the center of the top aluminum plate). Remove the red switch cover and turn the switch to off. Replace the red switch cover.

64. Scan Tool Diagnosis While many scan tools can be used, many generic scan tools are not able to read hybrid-specific diagnostic trouble codes (DTCs) or data. For best results, use the Honda factory scan tool.

66. Keep the Area Clean Whenever checking the oil level on a CVT transaxle, always clean the area around the dipstick before removing it. Even a little dirt can ruin a transaxle because the cones can be damaged by just a small amount of dirt.

67. SUMMARY 1. The first production hybrid electric vehicle sold in the United States was the Honda Insight. 2. The Honda Insight used a three-cylinder gasoline engine and Integrated Motor Assist (IMA) system to provide for idle stop, regenerative braking, and power assist during acceleration. 3. The Honda Civic hybrid is based on the conventional gasoline model and provides improved fuel economy and power. 4. The i-VTEC system closes both the intake and exhaust valves of all four cylinders of a four-cylinder Civic hybrid and three cylinders on the V-6 Accord hybrid during deceleration to increase the amount of kinetic energy captured by the regenerative braking.

68. SUMMARY 5. The batteries used in Honda hybrids are D-cell-size NiMHs connected in series to produce 144 or 158 volts. 6. The Honda Accord hybrid provides rapid acceleration and uses active engine mounts and active noise control to counter engine noise created during cylinder deactivation. 7. Honda hybrid engines use a linear air-fuel (LAF) sensor for fuel control. 8. The IMA battery module and the electronic modules are located behind the rear seat and are air-cooled. 9. Except for depowering the high-voltage system and some unique spark plugs used on the Insight, most service procedures are the same as for conventional vehicles.

69. REVIEW QUESTIONS 1. What are the differences in the engines used in Honda hybrid vehicles as compared to similar nonhybrid vehicles? 2. What features are used on the Honda Accord hybrid to reduce noise and vibration? 3. What is the difference between fuel shut off and auto stop? 4. What are the conditions that must be met for auto idle stop to occur? 5. How is the high-voltage electrical system disconnected in a Honda hybrid electric vehicle? 6. What are the safety and service procedures when working on Honda hybrid electric vehicles?