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Automotive Industry

SERVICE OVERVIEW OF THE 2006 LIGHT TRUCKS

Motor, Jan 2006 by Weissler, Paul

The level of technical complexity on the latest trucks and SUVs matches and occasionally exceeds what's found on passenger vehicles. And many truck-only systems and components promise to challenge service techs in the years to come.

The auto industry believes that America's love affair with trucks and SUVs is still going hot and heavy. The variety is not only getting greater, but the technical upgrades indicate that a lot of engineering atsr tention is being paid, even during few so-called carryover years.

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Honda enters the lovefest with the 2006 Ridgeline, its first "sort of" pickup truck. Also noteworthy for 2006 are the HUMMER H3, Dodge Mega Cab (certainly a sign that truck makers think "bigger is better"), seven-passenger Jeep Commander, new Ford Explorer, grownup Toyota RAV4 and Range Rover Sport, a model that proves you can have all the off-road capability you want, the luxury you can pay for and the cornering ability you thought required something else to drive. Toyota joins the "extreme" off-road charge with the FJ Cruiser, a new version of the Land Cruiser that proved its mettle on the legendary Rubicon Trail.

Let's cover the details by visiting the various manufacturers, one by one. Or, put another way, it's time to meet our makers.

Chrysler

The big news at Chrysler (pun intended) is clearly the Dodge Mega Cab pickup-20 ft. 8 in. long and available in 1500 (light-duty) and 2500 (heavyduty) versions. The full-size crew cab was extended 20 in., taking the length out of the 8-ft. pickup box, using the 160.5-in. wheelbase of the Ram 2500. So the cab interior is almost cavernous (111 in. long), and there's still a 6½-ft. bed. Rear doors open 85° for easy access. Because it's the heavy-duty platform, towing capacity is 15,900 lbs. There's not much you couldn't pull with this one.

To indicate how far rack & pinion steering has come, it's standard on the 2WD Mega Cab. When equipped with 4WD, however, recirculating-ball steering is used.

The base engine is the 5.7L HEMI V8, which develops 345 hp and 375 ft.-lbs. of torque and is mated to a five-speed automatic. It's the only engine on the so-called Ram 1500 Mega Cab; we say "so-called" because the platform (frame, chassis, axles and wheels) is actually the heavy-duty 2500. Although the Multi-Displacement System (MDS) cylinder cutout system is optional on the conventional Ram pickups (1500 series), it's standard on the Mega Cab.

The 5.9L Cummins in-line six-cylinder turbodiesel is an option only on the Mega Cab actually labeled 2500 (and standard on the 3500). A new six-speed manual is standard on both 2500 and 3500, with an automatic transmission optional.

The Ram 1500 conventional cab pickups not only get the MDS cylinder cutout, but a new full-time transfer case, as well. Labeled as the NV246, it contains an electronically controlled wet clutch that can apportion torque on demand between the front and rear in the AWD mode and provide 2WD, 4H, 4L and Neutral (for towing). And it's here we go again with the fluid: Aldiough ATF+4 is recommended for all the odier transfer cases with the Ram pickup, the NV246 requires a specific fluid, ATF NVG246.

Ram pickups with the 42RLE four-speed automatic (used with the 3.7 V6) will get variable line pressure as a phase-in. This feature (also used on the 545RLE five-speed automatic), adjusts line pressure according to load. The case is modified, and there are a specific valve body, line pressure sensor and duty-cycle variable force solenoid to vent excess line pressure, controlled by die transmission module. Because a vehicle could have either version of the 42RLE, you have to know which, to do accurate diagnosis and to order parts. There are obvious external differences, or you can look for the transmission sales code-DG6 without variable line pressure, DGV with.

Important tech note on conventional Rams or any vehicle with the HEMI 5.7 V8 that has MDS: The on-board diagnostics monitor oil pressure, temperature and other sensor readings and can log a trouble code P0521 (incorrect oil viscosity). Yes, this could be caused by oil contamination as well, but regardless, it means that the MDS function will not work properly. So it's not something that can wait until the next oil change is scheduled.

Jeep Commander is a spinoff from the Grand Cherokee, and is the first Jeep with a third row of seats. The second and third rows are theatre-style (each raised above the row ahead of it), the roof is just over 3 in. higher and the vehicle is just over 2 in. longer, dimensional features that enable it to retain the "trail-rated" label. A longer wheelbase, for example, could make some tight turns chancy during extreme off-roading.

Available engines are the familiar 3.7 V6, 4.7 V8 and 5.7 HEMI V8 with MDS. Jeep also offers a choice of three 4WD systems.

Ford

The Explorer, the best-selling SUV, still looks like an Explorer, but it's a very new vehicle under the skin. The V8 is still the 4.6L, but its a three-valve version with variable valve timing, adapted from the Mustang. It's rated at 292 hp (up from 239) and 300 ft.-lbs. of torque (up from 282). The 4.6 is a single-overhead-cam engine that benefits from a cam phaser (variable valve timing) on that one camshaft-somewhat like the pushrod camshaft phaser in certain GM engines.

Automotive Industry

SERVICE OVERVIEW OF THE 2006 LIGHT TRUCKS

Motor, Jan 2006 by Weissler, Paul

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