Question about Chevrolet Silverado 1500

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The red neutral indicator light is on for my auto transfer case 4WD selection. I cannot select 'auto', or '2WD'. The yellow indicator light next to these selections just flashes, and goes back to the red neutral position. The truck runs down the road with no problems.

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5 Suggested Answers

  • 4 Answers

SOURCE: my 2000 blazer won,t select 4wd hi/low or auto

there is a vacuum solonoid on the firewall in the middle with 2 vac lines and a 2 wire plug
thats ur problem
push the button and smack it with the handle of a screwdriver should work

Posted on Feb 07, 2009

  • 166 Answers

SOURCE: Transfer gear case shift jammed

There are four probable causes when the gear is stuck in one position, and they are precisely explained in this handy diagnostic article that I know will help narrow down the culprit of your difficulty:
http://yourhandymanzone.com/Your_Handyman_Zone_How_To_Pages_Vehicle_Car_Zone_Cars_Trucks_Vans_Transmission_System_Stuck_In_One_Gear.htm

Good luck!
Brad

Posted on May 26, 2009

stevenhurc
  • 450 Answers

SOURCE: electric 4WD selector switch on dash does not select/deselect 4WD. I wish to manually shift the selector at the gearbox if this is possible.

by swapping vaccum hoses on front diff shift on fly unit you can get out of 4wd or vise versa or by removing and sliding sleeve ring inside diff tube over, check range selection detent switch on this unit it is a on/off switch.these fail often

Posted on May 28, 2009

  • 1 Answer

SOURCE: 2004 GMC Sierra 1500 4wd. Auto transfer case light issue

I have the same problem. It is intermittent and sometimes shows up with service transmission message. To get rid of it just put the truck in park, press the 2 high button and shift into drive while it is still flashing. I will worry about it more when it blows up. You can drive with the vehicle showing the solid neutral and it seems to make no difference. It has to be a wake up problem between the control modules. It only happens on start up.

Posted on Sep 06, 2009

  • 61 Answers

SOURCE: 95 suburban with 4l60e and manual transfer case.

sounds like a solenoid problem or trans module,

Posted on Dec 13, 2009

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2002 ford ranger - Where is the 4x4 actuator located


On the transfer case
Transfer Case - Electronic Shift
The four-wheel drive electronic shift-on-the-fly feature electrically shifts the vehicle transfer case between 2WD, 4WD HIGH, and 4WD LOW. The system mode is selected by the operator through the mode select switch (MSS) on the instrument panel. The operator is informed which mode the system is in by two instrument cluster indicators: one for 4WD HIGH which appears as 4WD, and one for 4WD LOW, which appears as 4WD LOW. Shifts into 4WD HIGH can be made at any speed. When shifting into 4WD HIGH with the vehicle stationary, tooth blockage may occur preventing shift completion. When the vehicle is driven above 8 km/h (5 mph) the shift will complete. When shifting in or out of 4WD LOW, the four-wheel drive (4WD) control module requires that the vehicle speed be less than 5 km/h (3 mph), the brake pedal be applied, and the transmission be in NEUTRAL (automatic transmission) or the clutch pedal be depressed (manual transmission).
The gearmotor encoder assembly is mounted externally on the transfer case. It drives a rotary cam which moves the mode fork and range fork within the transfer case between the 4WD HIGH, 4WD LOW, and 2WD range positions.
The four-wheel drive (4WD) control module controls the gearmotor encoder assembly that shifts between 4WD HIGH, 4WD LOW, and 2WD modes.

Mar 17, 2017 | Ford Cars & Trucks

2 Answers

I have a 93 jeep Cherokee, it will move in 4wh and in 4wl but will not go back into 2wd?


Hello guy
try posting what 4wd system you have,? first.
command trac or select track, (the latter is full time)
part time or the full time system,
we cant guess it....
read the operators guide first, if a part time system only
as i suspect, stop driving on dry pavement.
it's only for ice, or dirt. part time. part time is not a full time system.
Command-Trac
shifting to 4wd on dry (means no ice) pavement causes, drive line wind up! and the gears to lockup. (see steering get tight in turns?> and is dangerous to drive it like this , you, me and the box)
posted here 100s of times.

http://www.rubicon-trail.com/4WD101/driveline-bind.html


the non grand Cherokee. early

had these choices
  • 1987-2001: New Process NP231 Command-Trac, part-time only, 2.72:1 ratio with low range
NP231 has the following settings: 2HI, 4HI, N, 4LO
  • 1987-2001: New Process NP242 Selec-Trac, full-time or part-time, 2.72:1 ratio with low range
NP242 has the following settings: 2HI, 4 full-time, 4 part-time, N, 4LO


as you can see you need to first know, what NP box you have or
photo your shift lever for 4wd, an post it and we tell you.

more facts, on select trac. (totally unlike command trac)
Selec-Trac locking hub is used on 4WD Cherokee. Selec-Trac
utilizes a non-disconnect front axle. Engagement of 2WD or 4WD is
accomplished at transfer case by means of mechanical shift linkage.
System allows full or part time 4WD. Selec-Trac can be shifted into
2WD or 4WD modes from inside the vehicle at any speed.
unquote
next from the service manual,
4WD TO 2WD
1) Place mode select switch in 2WD position. Transfer case
should shift to 2WD and not allow shifting into 4WD or LO range. Axle
should shift after transfer case shifts.
2) To determine if front axle has completed a shift out of
4WD into 2WD, position mode select switch back to 4WD position while
operating vehicle at slow speed. If vehicle shifts into 2WD, axle will
ratchet. If shift is not completed, transfer case will shift into 4WD
and hissing sound will come from mode select switch.
end quote.

if unsure read the FSM book its free.
shows you both systems and how to diagnose it.

in the box, click Cherokee,,then click 1993, and behold.
the real deal.

http://www.morris4x4center.com/knowledge-base/index.htm?utm_source=cj#service

4e7ebed4-9c81-4927-b26e-02808a82acff.jpg

May 10, 2016 | Jeep Cars & Trucks

1 Answer

How do I repair the four wheel drive on a 1999 Ford Ranger XLT?


It depends on what is wrong , is the 4x4 light flashing ? Are you aware of the complexity of the 4x4 system ? Has a electronic control module , has the ability to set an store DTC'S - diagnostic trouble codes !
Transfer Case The four wheel drive system is an electronic shift 4X4 system that allows the operator to choose between three different modes. The operator can switch 4X4 HIGH modes at any speed. To engage or disengage 4X4 LOW the vehicle speed must be less than 5 kph (3 mph), the brake depressed, and the transmission must be in NEUTRAL.
The shift motor sense plate, an integral part of the electronic shift motor, informs the generic electronic module (GEM) of the transfer case shift motor and contact plates A, B, C and D position.
The digital transmission range (TR) sensor is located on the LH side of the transmission, and informs the GEM when the transmission is in the NEUTRAL position.
The electronic shift motor is mounted externally at the rear of the transfer case. It drives a rotary cam which moves the mode fork and range fork within the transfer case between the 4X4 HIGH, 4X4 LOW and 2WD range positions.
When the GEM verifies the completion of the transfer case shift from 2WD to 4X4 HIGH (reading the contact plate positions), the GEM will then energize both pulse vacuum hublock (PVH) solenoids (supplying ground for 45 seconds). The PVH solenoid will allow a HIGH flow of intake manifold vacuum to the "wheel end hublocks", engaging the wheel end hubs to the front differential and transfer case to achieve four wheel drive.
Here are just a few DTC'S the system can set an store in the module !
P1804 4WD High Indicator Circuit Failure GEM GO to Pinpoint Test C . P1806 4WD High Indicator Short to Battery GEM GO to Pinpoint Test C . P1808 4WD Low Indicator Circuit Failure GEM GO to Pinpoint Test C . P1810 4WD Low Indicator Short to Power GEM GO to Pinpoint Test C . P1812 4WD Mode Select Switch Circuit Failure GEM GO to Pinpoint Test A . P1815 4WD Mode Select Switch Circuit Short to Ground GEM GO to Pinpoint Test A . P1820 Transfer Case CW Shift Relay Circuit - Failure GEM GO to Pinpoint Test A . P1822 Transfer Case CW Shift Relay Coil Short to Power GEM GO to Pinpoint Test A . P1824 4WD Electric Clutch Relay Circuit Failure GEM GO to Pinpoint Test A . P1826 4WD Low Clutch Relay Short to Power GEM GO to Pinpoint Test A . P1828 Transfer Case CCW Shift Relay Coil Circuit Failure GEM GO to Pinpoint Test A . P1830 Transfer Case CCW Shift Relay Coil Short to Battery GEM GO to Pinpoint Test A . P1838 Transfer Case Shift Motor Circuit Failure GEM GO to Pinpoint Test A . P1846 Transfer Case CONTACT PLATE "A" Circuit Failure GEM GO to Pinpoint Test A . Now are you sure you really want to mess with this ? You would need a factory diagnostic scan tool to check this out before you start replacing parts !
Here

May 30, 2015 | Ford Ranger Cars & Trucks

1 Answer

How do I fix my 99 blazer the dome lights won't turn on and the 4 who drive won't light up or work


In the instrument panel fuse box fuse # 8 CTSY LP 10A ,that's for the dome lights, fuse panel is left side of IP. What are you talking about 4 who drive won't light up or work ? 4 wheel drive ? Do you have two speed automatic or two speed selectable ?
Switch Indicator Lamps Do Not Light - One or More ? Check fuse #15 IP fuse box 10A 4WD . This is for two speed auto !

Circuit Description

The indicator lamps circuits consist of 5 individual lamps contained inside the mode/range switch assembly, they are AUTO, 4WD, 2HI, 4HI, 4LO and NEUTRAL. The AUTO, 4WD, 2HI, 4HI, and 4LO lamps are contained inside their respective range button. When the ignition is ON, the transfer case shift control module illuminates the indicator lamp that corresponds to the current ATC gear position by providing a ground through a current limiting driver.
The transfer case shift control module flashes each indicator lamp after a shift has been requested and will continue to flash until the transfer case shift control module can complete the shift. After a shift to AUTO, 4WD, 2HI, 4HI, or 4LO is made, the transfer case shift control module will flash that indicator lamp until the transfer case shift control module receives a high voltage signal on CKT 1695 from the front axle switch.
A solid state circuit located inside the switch supplies ignition voltage to the lamps. The solid state circuit also receives voltage whenever the headlamp switch is in park or headlamp position. When the solid state circuit receives voltage from the headlamp switch it will reduce the voltage that it supplies to the indicator lamps, dimming the lamps when the headlamps are ON.

Feb 07, 2015 | Cars & Trucks

1 Answer

How do I turn 4wd on?


    • 1 Start your Dodge truck's engine.
    • 2 Turn the electronic transfer case from "2WD" to "4WD Lock" to engage the high range 4WD, if the dodge truck is equipped with an electronic transfer case; otherwise, shift the transfer case lever from "2H" to "4H." The electronic transfer case is located on the instrument panel and is marked with "2WD," "4WD Lock" and 4WD Low." The lever-equipped transfer case is located to the right of your leg and is marked with "2H," "4H" and "4L."
    • 3 Shift the transmission into "Neutral" while the vehicle is either stopped or rolling at 2 to 3 mph to begin engaging in the low range 4WD. Turn the electronic transfer case to "4WD Low," if the Dodge truck is equipped with an electronic transfer case; otherwise, shift the transfer case lever from "2H" or "4H" to "4L."
    Tips & Warnings
    • Indicator lights will come on and alert you that your vehicle is in either the high or low range of 4WD.
    • Do not engage in the low range of 4WD drive if the transmission is in gear; you must shift to "Neutral" first.
    • Many Dodge trucks allow you to shift from 2-wheel drive to the high range of 4WD at up to 55 mph--consult your truck's manual to ensure that this is possible. Do not exceed 55 mph while engaged in the high range of 4WD. Do not exceed 25 mph while engaged in the low range of 4WD.
    • Do not engage in 4WD unless you are on slipper or rocky roads.

Sep 02, 2011 | 2005 Dodge Dakota

1 Answer

2005 GMC Yukon XL- Service 4 WD light comes on and the indicator light is not lit up nor can I change from 2WD to 4WD. It is push button selection with the option of Auto.


It is probably the encoder motor attached to the transfere case. look under the vehicle to see if there is signs of corrosion between the encoder motor and transfere case.

Nov 11, 2010 | GMC Yukon Cars & Trucks

1 Answer

2003 blazer will not come out of 4 lo, auto will flash when pressed and then go out


Check the fuse to your 4wd at the fuse panel at the end of the dash drivers side. If the fuse is good, put the transmission in neutral and listen for the Transfer case encoder motor to work when you push the button on the dash for 4wd hi then to 2wd. If you do not hear it working, inspect the wire harness at the Encoder motor to make sure there not damaged in anyway due to corrosion or disconnected.
Here's some info on how the 4wd system operates on newer Blazers for all those searching for the cause of the flashing dash switch light and no engagement.

4WD System Operation on 98 up (2nd Generation) Blazers/Jimmies

The front drive shaft always turns on “shift on the fly” systems so the drive train is at the same speed in the front as the rear or the whole thing would break when engaging 4Hi or Autotrac when moving. InstaTrac (NV243 case or NP1) has 3 buttons. AutoTrac (NV246 case or NP8) has 4 buttons and clutch packs in the transfer case and is the only system for on pavement driving! Prior were the NV231 (87-93) lever and NP233 (94-97) electric motor. Your VIN # is the only sure way the dealer can get correct parts/listings!
1. Select mode on dash switch
2. Signal goes to the Transfer case control module (TCCM) or computer located in the cab on the passenger side behind the kick panel.
3. If you want 4 Lo the TCCM commands the encoder motor on the transfer case to switch a lower gear in (requires putting the shifter in Neutral and be stopped or only going 2-3mph). Note that if 4 Hi selected no action done in the transfer case. The transfer case is chain coupled and has the low and high gear. You can put all systems into Neutral by pushing the 2Hi and 4Lo button at the same time when the key is in the run position (or running but not off or acc).
4. The left front (drivers side) CV axle is always engaged to the front differential, but the right side is not coupled in 2wd. There is an actuator located under the battery tray that when commanded is vacuum actuated and pulls a cable from it to the right side CV axle coupler engaging that axle. A sensor is on that axle that tells the TCCM the axle position.
5. On 99up there is an additional vacuum switch on the firewall that switches the vacuum on and signals the TCCM also.
6. The dash light on the selector switch flashes while all this is occurring and will not switch out of 2wd unless all parts report correctly – same on the switch to any mode or back to 2wd.

So, there are a lot of possible failure areas with actuators/computer/motor/sensors/vac hoses and a special scanner is required to read the codes when the Service 4WD light comes on. But, a few things can easily be done before going to the dealer.
1. Check all vacuum hoses from the intake to the drivers side reservoir can, then to the extra switch (99up) and down to the under battery actuator. Small hose is 5/32 and larger is 7/32”.
2. See if the actuator pulls the front axle cable to engage it. If not and all hoses are good the diaphragm may be leaking on the actuator. If it engages but the light is still flashing remove the indicator switch on the front axle (only electrical plug in there) and manually push it in with the connector plugged in and see if the light stops, if so replace.
3. Listen to the encoder motor clunk when 4 Lo selected. If not working look at the wiring going to it for any cuts/breaks and repair if any found. Another indicator switch on top of this case. The fluid in the AutoTrac case should be the newer light blue Autotrak –II synthetic P/N 12378508 ($7 qt) not the red Dexron III.
4. If the light keeps flashing after this then disconnect the battery for 30 minutes for a TCCM reset, just make sure you turn off your radio first.
5. Still not working – take it to the dealer and stop at the bank on the way for $$$$!

12577412 is the part number for the Transfer Case Control Module (TCCM), or you can do the Salvage Yard for $15.00 if that's the part that has gone bad.

Jan 22, 2010 | 2003 Chevrolet Blazer

2 Answers

4wd does not work


Electronic Shift On the Fly (ESOF) Operation
The ESOF system is an electronic shift 4x4 system that allows the operator to choose between two different 4x4 modes as well as 2-wheel drive. The operator can switch between 2WD and 4WD HIGH mode at speed. To engage or disengage LOW Range, the vehicle speed must be less than 5 kph, the brake depressed, and the transmission must be in NEUTRAL.

The transfer case is equipped with an electromagnetic clutch which is located inside the case. This clutch is used to spin up the front drive-line when shifting from 2WD to 4x4 High mode at speed. When the control switch on the instrument panel is turned, the generic electronic module (GEM) recognizes that a shift has been requested and activates the electromagnetic clutch and the relays which power the transfer case shift motor. When the shift motor reaches the desired position as determined by the contact plate position inputs to the GEM, power to the shift relays and motors will be removed. When the transfer case front and rear output shafts are synchronized, the spring loaded lockup collar mechanically engages the main-shaft hub to the drive sprocket. Finally, the front axle collar is engaged and the electromagnetic clutch is deactivated.

Shift Between 2WD and 4x4 HIGH:
Shifts between 2WD and 4x4 HIGH can be made at speed. Listed below are the inputs and outputs needed by the GEM to execute a change between any of these modes.

Feature Inputs:
*4WD Mode Switch (Various resistances).
*Contact Plate Position Inputs A, B, C, D (grounded when closed, open circuit when open).

Feature Outputs:
*4x4 Shift Motor Relay Outputs
*Transfer Case Clutch Relay (grounded when relay is on, open circuit when relay is off).
*4x2/4x4 Vacuum Solenoid (grounded when activated, open circuit when deactivated).
*Cluster Indicators (ground when activated, open circuit when deactivated).

Shifting Into/Out of 4WD LOW:
When shifting into or out of 4WD LOW, the GEM requires that the vehicle speed be less than 5 kph, the brake is applied, and the transmission is in NEUTRAL.

Feature Inputs:
*4WD Mode Switch (Various resistances).
*Contact Plate Position Inputs A, B, C, D (grounded when closed, open circuit when open).
*VSS Sensor (Sinusoid Signal: 0.7V-20V, 2.2 Hz/mph).
Brake Input (battery voltage when brake is depress, open circuit when not activated).
*Transmission Range Sensor (grounded when transmission is in NEUTRAL, open circuit otherwise).
8Start/Clutch Depressed Input

Feature Outputs:
*4x4 Shift Motor Relay Outputs
*4x2/4x4 Vacuum Solenoid (grounded when activated, open circuit when deactivated).
*Cluster Indicators (grounded when activated, open circuit when deactivated).

4WD Mode Switch
A rotary switch allows the vehicle operator to choose between 2WD, 4WD HIGH, and 4WD LOW modes of 4x4 operation.

GEM Module
The Generic Electronic Module (GEM) controls the operation of the 4x4 system

Vehicle Speed Sensor
The vehicle speed sensor (VSS), mounted in the rear of the transfer case, informs the GEM of the vehicle speed.

Transfer Case Shift Motor Sense Plates

The shift motor sense plate, an integral part of the electric shift motor, informs the GEM to the positions of the transfer case

Transmission Range Sensor
Located on the left side of the transmission, this sensor informs the GEM when the transmission is in the NEUTRAL position.

Electric Shift Motor
The electric shift motor, mounted externally at the rear of the transfer case, drives a rotary cam which moves the mode fork and range fork within the transfer case to select between the 2WD, 4WD HIGH, and 4WD LOW positions.

4x4/4x2 Vacuum Solenoids
These two solenoids are attached to the upper RH side of the engine compartment dash, and alternately route vacuum to the vacuum motor which engages/disengages the center axle disconnect collar in the front axle assembly.

4x4 Shift Motor Relay
A module containing two relays which under the control of the GEM, shift the transfer case shift motor between the 2WD, 4WD HIGH, and 4WD LOW modes.

Transfer Case Clutch Relay
An electromechanical relay is used to activate the transfer case clutch within the transfer case.

Good luck and hope this helps,but start with the simple and check the fuses and wire harness. Both white/light blue stripe wires should have 12V in run. The GEM will ground the left side (closest to engine) solenoid to disengage the front axle. It will ground the the right side solenoid (closest to fender) to engage the front axle. If the GEM doesn't see Neutral it will not let the truck come out of 4Lo. If the GEM had water leaking on it it may well be the root of the problem. The shift motor only has power when the GEM sends it a signal to move the shift lever. Once the shift is completed the motor shuts off. There are 2 wires that control the shift motor. A yellow and an orange. The GEM alternates between 12v and Ground to these wires to control which way the motor turns. The GEM uses the transfer case shift relay module to control the power to the motor. There are contact plates inside the shift motor assembly that indicate the position that the shift lever is in. This is what the GEM used to know what the T-case is doing. Any one of these components can fail.







Jan 10, 2010 | 2002 Ford Explorer

1 Answer

1996 ford explorer 4wheel drive will not engage into the hubs need to know how it works


make sure your 4WD switch is working.and fuse is okay.because your 4WD is control by 4 electric shift motors in which drive a rotary cam which moves the mode fork and range fork inside the transfer case to select between 2WD HIGH A4WD - 4WD HIGH AND 4WD LOW RANGE.a shift motor sensing plate on the shift motor monitors the range in which the transfer case is operating a transmission range sensor monitors the gear position of the transmission.which must be in neutral to shift into low.a pair of solenoids one for 2WD one for 4WD.mounted on the upper right firewall route vacuum to the vacuum motor which engages and disengages the center axle disconnect collar in the front axle assembly.a 4 x 4 shift motor relay module contains two GEM controlled relays which shift the transfer case shift motor between 2WD and 4WD modes.a solid state clutch relay activates the A4WDclutch inside the transfer case.

Dec 13, 2009 | 1996 Ford Explorer

2 Answers

2004 GMC Sierra 1500 4wd. Auto transfer case light issue


I have the same problem. It is intermittent and sometimes shows up with service transmission message. To get rid of it just put the truck in park, press the 2 high button and shift into drive while it is still flashing. I will worry about it more when it blows up. You can drive with the vehicle showing the solid neutral and it seems to make no difference. It has to be a wake up problem between the control modules. It only happens on start up.

Aug 27, 2009 | 2004 GMC Sierra 1500 Crew Cab

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