September 2006 Archives

A new intermediate-voltage GM hybrid system debuts in the 2007 Saturn VUE Green Line(fig. 1).

This is one of three innovative hybrid systems that GM plans to introduce on up to 12 models. GM launched the world's first hybrid pickup trucks in 2004, the Chevrolet Silverado and GMC Sierra. GM is also developing an all-new Two-mode full hybrid system, which will first be marketed in the new Chevrolet Tahoe and GMC Yukon full-size SUVs in 2007.

The Saturn VUE Green Line hybrid uses a 2.4-Liter variable valve timing (VVT) Ecotec engine, a modified 4T45E automatic transmission, sophisticated controls and a precision generator assembly (with starter). This system will be featured in upcoming passenger vehicles as well.

In this application, the engine is estimated to produce 170 peak horse power at 6600 rpm and 162 lb-ft of torque at 4400 rpm. This is 27 hp more than the 2.2L engine that powers the conventional VUE. The hybrid-enabled transaxle includes an auxiliary oil pump to maintain oil pressure when the engine is off and unique hybrid controls to ensure seamless hybrid operation.

REASONS FOR IMPROVED FUEL ECONOMY

The Saturn VUE Green Line hybrid delivers an estimated 20% improvement in fuel economy, depending on driving conditions. It is expected to carry an EPA fuel economy rating of 27 mpg city and 32 mpg highway, the best highway fuel economy of any SUV presently on the market. (8.8 L/100 km city and 6.7 L/100 km highway in Canada, determined using approved Transport Canada methods)

These fuel savings are the result of aerodynamic design and the functions of the hybrid system.

Improved aerodynamics include a 1-inch reduction in ride height, a rear spoiler, and elimination of fog lights and roof rack.

The Saturn hybrid functions include:

- Engine shuts off when vehicle is stopped to minimize idling

- Engine restarts as brake pedal is released

- Early fuel cutoff during vehicle deceleration

- Regenerative braking during deceleration to help charge the hybrid battery

- Performs intelligent battery charging when it's most efficient

The Saturn VUE hybrid also provides electric power assist while driving or during acceleration when needed. During wide-open throttle or an aggressive passing maneuver, the system improves vehicle launch and acceleration feel by assisting the engine to achieve maximum power.

The system is designed to automatically maintain accessory functionality and passenger comfort when the engine is stopped so that hybrid operation is transparent to the driver and passengers.

COMPONENTS (fig. 2)

TIP: Many hybrid-specific parts are on restriction and must be obtained through TAC.

The Saturn VUE Green Line hybrid utilizes these major components:

A - A precision generator with starter (fig. 3) (3-phase, 65 Nm stall torque, 3kW continuous power, hard-mounted to engine)

B - Generator Control Module (fig. 4) with inverter and power converter, that controls the generator with starter and provides 12-volt vehicle accessory power

C - A 36V advanced, nickel metal hydride (NiMH) hybrid battery pack (fig. 5) capable of delivering and receiving more than 10kW of peak power

D - E67 engine control module with sophisticated Hybrid Supervisory Software to manage both engine and hybrid system operation

E - A new engine accessory drive with dual tensioner assembly and 7-rib Aramid cord belt(fig. 6 and 7) that enables reliable transfer of torque for both motoring and generating

F - The hybrid-enabled 4T45-E electronically controlled overdrive transaxle that includes an auxiliary oil pump and unique hybrid controls to ensure seamless hybrid operation.

G - Standard 2.4L 4-cylinder VVT Ecotec engine

POWER ELECTRONICS FUNCTIONS

The power electronics provide three basic functions.

When the system is in the motoring mode, the power electronics invert the hybrid electrical power from direct current (DC), to 3-phase alternating current (AC) which is then passed on to run the generator with starter as a motor. This provides quick engine auto-starts, torque smoothing, and electric power assist as needed.

When the system is generating electricity for subsequent hybrid battery storage, the power electronics rectify the 3-phase AC electrical power input to a DC electrical power output. In this mode, the energy required to drive the engine may come from either gasoline when accelerating or the kinetic energy of the moving vehicle when decelerating with the fuel cut off.

Finally whether motoring or generating, the power electronics convert the hybrid battery DC electrical input to a low voltage electrical output that is used to provide both vehicle accessory power and to keep the 12V battery charged.

GENERATOR WITH STARTER DRIVE DETAILS

Because the generator with starter has to operate both as a motor and as a generator, accessory drive torque transfer must be well managed. A novel, dual-tensioner assembly combines a hydraulic tensioner and friction-based rotary tensioner on a common, pivoting arm. This design ensures sufficient tension is available in both motoring and generating modes, while helping to reduce overall belt tension. A high strength Aramid cord belt is used to ensure robustness.

HILL START ASSIST FEATURE

When a conventional vehicle is stopped on a hill, it's held in place by the engine-idle torque on the driveline as well as by the brakes. In the Auto Stop Mode, the hybrid's engine is not running, and the brakes hold the vehicle in place until the pedal is released. In the hybrid, it's necessary to release the brake pedal to restart the engine.

The hill start assist feature minimizes vehicle rolling during the transition between brake release and engine restart. The Brake Delay Valve maintains pressure in the brake lines as the pedal is released and the engine starts. Then the Brake Delay Valve seamlessly releases the brakes.

A/C OPERATION

The A/C controls on the VUE hybrid permit the driver to select several operating modes.

Economy mode (green light) allows the engine to auto-stop. When this happens, the A/C compressor also stops, which may allow cabin temperature to rise. But fuel economy is maximized. To maintain cabin comfort in the economy mode, the recirculation button can be energized.

Normal mode (yellow light) does not permit the engine to auto-stop, so cabin cooling is maintained. This mode may be necessary in conditions of high ambient temperatures and humidity. But fuel economy is reduced.

ELECTRONIC CONTROLS

All of the sophisticated hybrid control algorithms are stored in the conventional engine control module (ECM). An additional hybrid supervisory control module was not needed. The ECM communicates with the other vehicle and powertrain controllers to supervise all hybrid functions.

INSTRUMENTATION

There are several unique instruments and lamps on the IP of the VUE hybrid (fig. 8).

A Hill Hold telltale

B Fuel Economy (eco) telltale

C Tachometer, with AUTO STOP (will auto restart) and OFF (requires key for start) modes indicated

D Charge/Assist Gauge

E Hood Ajar telltale

SERVICE SAFETY CONSIDERATIONS

IMPORTANT: The 36V hybrid system (charged at 42V) produces voltages higher than a conventional 12V system (charged at 14V), and even small currents can be dangerous.

IMPORTANT: All intermediate-voltage circuits are identified with blue wiring conduits.

IMPORTANT: The appropriate safety precautions are described in SI. Become familiar with these precautions and always observe them.

Some important safety practices:

- Avoid wearing jewelry or watch

- Remove or cover belt buckle

- Wear safety glasses

- Wear rubber-soled shoes

- It is recommended to wear class 0 isolation gloves (leather outside, rubber inside), which are rated up to 1000V (fig. 9)

- Know where the components are located in the hybrid system and treat them with respect

- Thanks to Keith Newbury and Bob Wittmann, Brand Quality



HYBRID TRAINING AND TOOLS

Training

GM Service Technical College is offering these hybrid training courses. To enroll, refer tohttp://www.gmtraining.com

TIP: Canadian retailers should refer to latest training availability in the Product Service Training Course Catalogue located on the GM infoNET.

Tools

The EN-48079 Hydraulic Belt Tensioner Compressor is required to service the hybrid VUE (available from SPX/Kent-Moore 1.800.345.2233 

There is an update to the Tech 2 navigation for the NAO Tech 2 software download.

For 2007, the Hummer H3 is built in two locations: Shreveport, Louisiana and Struandale, South Africa. Each has a unique selection in the Tech 2.

The World Make Identifier (1st three characters of the VIN), is how the two vehicles are differentiated and selected on the Tech 2.

Be careful to select the correct vehicle, based on the World Make Identifier. This will ensure that you access the correct Tech 2 diagnostics for the vehicle you are working on.

- Thanks to Gary McKay

The Cadillac CTS, SRX, and STS are equipped with provision for installing a recovery loop. These loops are used to assist in pulling the vehicle from snow, mud, etc. Using the loop avoids having to dig beneath the vehicle to locate a suitable location to attach a cable.

To use the recovery loop, remove the access panel to expose a weldnut on the vehicle's frame. The loop is installed by screwing it into the weldnut.

The STS and SRX have front and rear attachment points (fig. 10 and 11). The CTS with dual exhaust has a rear attachment point only, and the CTS with single exhaust has none.

This information applies to the following vehicles:

The DTCs which might be set are B0012, B0013, B0016, B0019, B0020, B0022, B0023, B0026, B0033, B0040, B0042, B0044.

Inspect for a loose, missing, or broken Connector Position Assurance (CPA) retainer
(fig. 14). If loose, remove the connector and reinstall correctly by first pushing the connector body in completely and then pushing in the CPA completely.

If the CPA is broken, missing, or will not seat connector correctly, replace the CPA retainer with part number 54590003 (orange CPA) that is located in the SIR Repair tray of the J-38125 Terminal Repair Kit.

TIP: If the CPA retainer part number 54590003 (orange CPA) can't be located in Terminal Repair Kit, contact SPX/Kent-Moore at 1.800.GM.TOOLS to obtain a new package of five.

- Thanks to Mark Haning

This information applies to GM light and medium duty diesels.

Some fuel companies may be putting warning labels on their diesel fuel pumps which describe the sulphur content of the fuel and also advise customers not to use 500 ppm (parts per million) sulphur fuel in a 2007 or later vehicle.

At this time, customers may find more than one type of number 2 diesel fuel available.

LSF (low sulphur diesel fuel) has a 500 ppm sulphur content. ULSF (ultra low sulphur diesel fuel) has a sulphur content of 15 ppm or lower. Off Road Fuel has a 500 ppm or higher sulphur content.

All fuel companies will start transitioning to ULSF (15 ppm sulfur max) in mid-2006. Refineries in the US and Canada are required to start producing ULSF on June 1. US and Canadian supply terminals must be converted to ULSF by September 1 and retail stations must be converted by October 15.

In the US, EPA's pre-compliance reports indicate that 95% of on-road diesel fuel will meet the 15 ppm standard on a nationwide basis. All High Sulfur Fuels (500 ppm sulphur) and Off Road Fuels must be segregated and clearly marked. In Canada, only 15 ppm on-road diesel fuel will be available nationwide by October 15.

Proper Fuel Usage for GM Vehicles

In January 2007, a new 6.6L Duramax Diesel will be released (RPO code LMM -- eighth digit of the VIN is a 6). The 2007 LMM diesel equipped vehicles will require the use of ULSF for proper operation of the emission control system. Per regulation, these vehicles will be labeled ULSF Required in two locations -- near the fuel filler and on the IP (fig. 15). The owner manual and diesel supplement will have several instances and sections which define proper fuel use.

All other light and medium duty 6.2L, 6.5L, and 6.6L RPO codes LB7, LBZ, and LLY diesel engines (including 2007 model year LBZ and LLY) can use either the LSF (low sulphur diesel) or ULSF (ultra low sulphur) diesel fuels.

Off Road Fuels should not be used in any General Motors highway use vehicles.

- Thanks to Don Langer

Instructions in SI have been revised on servicing the Inside Rear View Mirror (ISRVM) assembly RPO DD8 on the 2005-06 Chevrolet Corvette. See document 1332917. The procedure has been revised for releasing the mirror from the windshield.

Remove the electrical connector from the back of the inside rearview mirror.

Rotate the mirror counterclockwise until an audible click is heard (fig. 16). Remove the inside rearview mirror.

To install, reverse the procedure. An audible click is heard when the inside rearview mirror is fully seated.

TIP: DO NOT pull rearward on the rearview mirror while removing or installing the mirror. Damage to the support or to the windshield may occur.

TIP: A slight movement of the mirror base from left to right is considered normal.

- Thanks to Dino Poulos

A new bulletin 05-02-32-007C is being issued to consolidate information about power steering noise concerns from three previous bulletins 05-02-32-007B, 01-02-32-001G and 06-02-32-005.

Refer to bulletin 05-02-32-007C for details and applicable vehicles. Here are some highlights.

MOAN, GROAN OR WHINE

A moan, groan or whine type noise may occur during steering maneuvers or while driving. It may be more noticeable on a cold engine when turning a corner.

The noise may be the result of low power steering fluid which may be caused by:

- variations in factory fill

- system purges air over time

- hose expansion and contraction

- fluid level not being checked regularly due to location of reservoir

TIP: If the fluid level appears low, don't assume a leak exists until it is verified.

TIP: Inspecting fluid level is part of new car PDI. Fluid should be between the add and hot marks on the dipstick.

Diagnostic Tips

With the fluid at the proper level in the reservoir, start the engine and turn the steering wheel lock to lock a few times. This simple step will frequently correct moan, groan or whine conditions.

If large amounts of oil residue suggest a leak, add dye to the system and inspect with a blacklight. If a leak is found, repair the source. If the source cannot be found, DO NOT replace any steering system components.

TIP: Three apparent leaks may be from external causes. Gears should not be replaced for these conditions.

- Fluid on the steering gear body may be residue from assembly plant processes (fig. 17).

- Fluid on convoluted boots may be liquefied assembly grease from the rack teeth (fig. 18).

- An apparent fluid leak at the pinion adjuster plug may be assembly grease containing lithium. This grease appears yellow like leak detection dye when viewed through yellow tinted goggles.

TIP: A quick check for a rack seal leak is to remove the air equalization tube from between the convoluted boots. Hold the tube vertically and tap on a firm surface 5 or 6 times. If no oil comes out, the inner rack seals are not leaking.

SNAP OR POP NOISE

A snap or pop type noise may come from the front of the vehicle, usually during steering wheel rotation.

This may be caused by the inner tie rod boot collapsing unevenly, allowing for contact between the inner tie rod and the boot. This condition is sometimes referred to as snaking.

Diagnosis

The bulletin explains how to detect the contact condition with your fingertips on the inner tie rod boot boot, while an assistant rotates the steering wheel from lock to lock.

Correction

If contact exists, replace the inner tie rod boot. Refer to the Rack and Pinion Boot Replacement procedure in SI. DO NOT replace the steering gear.

TIP: If the boot is not snaking and you cannot feel the inner tie rod contact the boot, refer to the next condition, Clunk Noise While Turning.

CLUNK NOISE WHILE TURNING

A clunk type noise may come from the front of the vehicle during a turning maneuver. This condition may also be felt through the steering wheel when the vehicle is stationary and the wheel is rotated from stop to stop.

Cause

This condition may be caused by inadequate lubrication of the steering intermediate shaft, which results in a slip stick condition.

Diagnostic Tip

Important: Misdiagnosis may lead to replacing the steering gear. During replacement, if the I-shaft is stroked, the original grease will be distributed in the I-shaft. It appears that gear replacement eliminated the clunk. But, after the customer drives the vehicle for several miles and dissipates the original grease, the noise may return.

The bulletin explains how to duplicate the customer's concern and isolate the I-shaft. If a clunk is felt in the steering wheel, the MOST likely cause is the I-shaft, not the steering gear.

Correction

Lubricate the intermediate I-shaft with Grease Kit p/n 26098237. Do not replace the intermediate I-shaft.

Instructions for using the kit are included in the bulletin.

- Thanks to Chris Anderson