Question about 2002 GMC Yukon XL

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'2002 yukon service 4x4 light on

Service 4x4 light on and will not illuminate the 2h, 4H or 4L indicator that 4x4 is engaged or disengaged.

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  • Anonymous Mar 19, 2014

    My 1992 isuzu pickup pup 4x4 want stay in 2H or 4H but drives fine in 4L

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  • 56 Answers

Most of the time this problem is caused by the 4 wheel drive switch. Usually you can just replace the switch and that will fix the problem. I have replaced many of those switches and that has fixed the problem.

Posted on Jan 06, 2009

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2003 ford f250 superduty 4x4 don't work no indicator light on dash changed4x4 switch module what next?


Check for codes. Usually part stores do it for free. here is how it works.
Principles of Operation

Electronic Shift on the Fly (ESOF) System

The electronic shift on the fly (ESOF) system is an electronic shift system that allows the operator to choose between 2 different 4x4 modes as well as 2-wheel drive. The operator can switch between 2H and 4H mode at speeds up to 88 km/h (55 mph). To engage or disengage 4L, the 4x4 generic electronic module (GEM) requires that the vehicle speed be less than 5 km/h (3 mph), the brake pedal depressed and the transmission in NEUTRAL (or clutch pedal applied on manual transmission vehicles). This system contains pulse vacuum hublocks (PVH). The selector on the hublock, when turned fully counterclockwise to the AUTO position, engages/disengages the hub depending on the driver-selected 4x4 mode of operation. The hublocks also contain a manual override. When the selector is rotated fully clockwise to the LOCK position, the 4x4 vacuum and electronic system used for coupling the front axle to the wheel is bypassed.

The transfer case is equipped with a dual-cone synchronous clutch. This clutch is used to synchronize the front driveline to the rear. All other internals operate in the same manner as the manual shift system. When the mode select switch (MSS) on the instrument panel is turned, the 4x4 module powers the transfer case motor, which activates a shift fork and engages the clutch. When the shift motor reaches the desired position, as determined by the encoder position inputs to the 4x4 module, power to the shift motor is removed. When the transfer case front and rear output shafts are synchronized, the lockup collar mechanically engages the mainshaft hub to the drive sprocket. At this point, the front axle PVHs are engaged. Instrument cluster "4x4" and "Low Range" indicator operation is controlled via hardwired outputs from the 4x4 module.

Electronic Shift Transfer Case

The New Venture Gear NV 273 electronic shift transfer case is a 3-piece aluminium design. The unit transfers engine power from the transmission to the front and rear axles. Under normal driving conditions the unit is in 2-wheel drive high (2H), but when desired, the operator may shift into 4-wheel drive high (4H) or 4-wheel drive low (4L). The transfer case is shifted electronically. The unit is lubricated by a positive displacement fluid pump that channels fluid flow through holes in the mainshaft.

The encoder assembly used for mode indication is of a Hall-Effect type. The system uses a total of 4 independent transistors for mode recognition. Each transistor is associated with a specific range of motor movement. When the circuit to each transistor is closed, a ground path to any of the A, B, C or D encoder pins is accomplished. When the circuit to each transistor is open, the connection to any of the A, B, C, or D encoder pins is pulled to voltage. Mode indication is "decoded" by the 4x4 module based on the varying combinations of signals coming from the transistors.

Hublock Operation

With the hublocks in the Auto position, the 4x4 ESOP system uses timed vacuum sequences to lock and unlock the wheel ends when switching the instrument panel MSS between 2WD and 4x4 modes. A high vacuum level (222 mm or 8.75 in. Hg and greater) is applied to the hublocks to lock the internal spring mechanism that engages (locks) the hublocks for 4x4 mode, and a lower vacuum level (114 to 184 mm or 5.9 to 7.1 in. Hg) is applied to unlock the spring mechanism that disengages (unlocks) the hublocks for 2WD mode. The vacuum signals are supplied to the hublocks by system components, including the 4WD control module or GEM, wiring harness, solenoid, vacuum harness and vacuum seals. As a first step in service, eliminate obvious items such as loose wiring connections, loose vacuum connections or damaged vacuum lines.

Dec 12, 2014 | 2003 Ford F250

1 Answer

I now have a suzuki samuri and do not know how to use 4x4 gears


Using the shorter gear leaver in the samurai, the gear choices are arranged in a simple U fashion. They are arranged in sequence. At left top, bottom, right middle and right top you have 2 high(2H), 4 hight (4H), neutral(N) and 4 low (4L).
2H- Engages rear wheel drive only.
4H- Engages all wheels in 4X4 mode.
N- Disengages all wheels (if you gonna tow your vehicle)
4L- Engages all wheels in 4X4 mode with 50% more torque but you cut your top speed by an equal amount.
If you have the OEM gear knob the diagram of the layout of the transfer box should be imprinted. 2 high should be used on dry and mildly wet paved roads. Using 4L or 4H in these conditions may result in damage to your transfer box. You may use 4L or 4H in any other road conditions.

Jan 05, 2013 | 1987 Suzuki Samurai

1 Answer

How do you use 4 wheel drive on a suzuki samuri


the samurai doesn't have 2L it has 2H.
there are 4 modes on the transfercase. 2H, 4H, N and 4L.
2H engages the rear wheels only while 4H and 4L engages all 4 wheels. N disengages all 4 wheels, useful for flat towing.

Jan 05, 2013 | 1987 Suzuki Samurai

1 Answer

I have 99 frontier 4x4 v6 with atp light on engien wont get over 1500 rpms


ATP = Automatic Transmission Park Warning Light.

The light indicates that the automatic transmission parking function is not engage.

Shift the transfer control shift lever into the 2H, 4H or 4L position when the warning lights comes ON. __________________

Jun 06, 2012 | 1999 Nissan Frontier

1 Answer

Transfer case shifter is locked up in 2H on 4x4 montero sport 2002


Mine did the same thing so I removed the center console and then the boot around transfer case shifter and the shifter it self.
This is when I discovered a broken linkage that had wedged itself between the 4L & 4H shafts in the transfer case. I removed the broken parts and reassembled and it will shift between 2H & 4H but not 4L until the broken plastic linkage is replaced. Found your post while lookin for the replacement part so I thought I would try to help. Good Luck

Feb 08, 2011 | 2000 Mitsubishi Montero Sport

1 Answer

My 2001 Silverado is stuck in 4L. When I select any other position, 2H, Auto, or 4H it blinks 3 or 4 times, makes clicking sounds behind the dash and then goes off...no amber lights on any drive indicator...


I would advise you to check your fuses in the block under the hood and on the driver's side of your dash. If that doesn't fix your problem, you probably need a new transfer case selector motor. A quality aftermarket replacement can be purchased for around $250, and is fairly easy to change. Hope this helps!

Sep 04, 2010 | Chevrolet Silverado 1500 Cars & Trucks

1 Answer

How do I use the 4 wheel drive on my Ford Ranger XLT 2.5 TDi 2004


4L only to be used in extreme condtions
N
4H for off road/snow/ice
2H - normal driving

when switching to 4H vehicle must be stationary, as when changing from 4H to 4L
but it is possible to change from 4H back to 2H while in motion.
when 4wd is engaged a lamp will illuminate on dials telling that the hubs are free wheeling, when changing back to 2H you must press corresponding switch to dis-engage this function

Jan 08, 2010 | 2004 Ford Ranger

4 Answers

How do you know when your in A4WD?


no you have it reversed....if the light is on its in awd if its off its not

Feb 14, 2009 | 2006 Ford Expedition

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