4 wheel drive wont disengage

Hi:

DTC P1833 - Transfer Case Differential Lock-Up Solenoid Open Circuit


The Pulse Vacuum Hublocks Do Not Operate Properly (Transfer Case Motor Movement and Front Driveshaft Operate Properly)


Double check the vacuum lines for any breaks, kinks or even disconnected. Also double check the hub lock sea


PINPOINTTEST E: THE PULSE VACUUM HUBLOCKS DO NOT OPERATE PROPERLY (TRANSFER CASE MOTORMOVEMENT AND FRONT DRIVE SHAFT OPERATE PROPERLY CONDITIONS DETAILS/RESULTS/ACTIONS E1 LEAK TEST THE WHEEL ENDS AND LOWER VACUUM SYSTEM - SOLENOID OUTPUT Raise and support the vehicle;
Disconnect PVH Solenoid Vacuum Connector
NOTE: This step may require rapid pumping for up to 10 seconds. Connect a hand vacuum pump to the PVH solenoid upper port hose connector and try to pull a vacuum to 15 in/Hg.

• Does the vacuum drop exceed 0.5 in/Hg in 30 seconds?

Yes GO to E22.
No GO to E2.
E2 LEAK TEST THE UPPER VACUUM SYSTEM - SOLENOID INPUT Connect a hand vacuum pump to the PVH solenoid lower port hose connector and try to pull a vacuum to 15 in/Hg.

• Does the vacuum drop exceed 0.5 in/Hg in 30 seconds?

Yes GO to E3.
No GO to E5.
E3 LEAK TEST THE A/C SYSTEM Disconnect A/C Vacuum Input Line
Connect a hand vacuum pump to the A/C vacuum input line connector and try to pull a vacuum to 15 in/Hg.

• Does the vacuum drop exceed 0.5 in/Hg in 30 seconds?

Yes DIAGNOSE the A/C system; TEST the system for normal operation.
No GO to E4.
E4 CHECK THE VACUUM SYSTEM RESERVOIR AND VACUUM LINES Connect A/C Vacuum Input Line
Disconnect Vacuum Reservoir Output Tee Connector
Connect a hand vacuum pump to the vacuum reservoir output line connector and try to pull a vacuum to 15 in/Hg.

• Does the vacuum drop exceed 0.5 in/Hg in 30 seconds?

Yes DIAGNOSE the engine vacuum system; No REPAIR and/or REPLACE the vacuum reservoir output tee fitting or vacuum line between vacuum reservoir tee fitting and PVH vacuum solenoid. TEST the system for normal operation.
E5 CHECK THE PVH VACUUM SYSTEM FOR ENGINE VACUUM Connect a vacuum gauge to the PVH solenoid lower port hose connector and measure the vacuum level.

• Is the vacuum level greater than 11 in/Hg?

Yes GO to E7.
No GO to E6.
E6 CHECK THE ENGINE AND PRIMARY VACUUM LINE FOR VACUUM Engine Vacuum Output Connector
Connect a vacuum gauge to the engine vacuum output connector and measure the vacuum level.

• Is the vacuum level greater than 11 in/Hg?

Yes REPAIR or REPLACE the vacuum reservoir or vacuum lines between the PVH solenoid vacuum input line and vacuum reservoir input line. TEST the system for normal operation.
No DIAGNOSE the engine vacuum system;
E7 CHECK THE SOLENOID VALVE FOR LEAKAGE Connect PVH Solenoid Vacuum Connector
Disconnect the LH wheel end vacuum line connector.
Connect a tee fitting and vacuum gauge between the LH wheel end vacuum line connector and PVH solenoid vacuum line output connector. Wait a minimum of 60 seconds and measure the vacuum.

• Is the vacuum level greater than 1 in/Hg?

Yes REPLACE the PVH vacuum solenoid. TEST the system for normal operation.
No GO to E8.
E8 CHECK THE PVH SOLENOID FOR PROPER VACUUM OUTPUT LEVEL - 4X4 ENGAGED Measure the vacuum while switching the 4X4 mode switch to 4X4 HIGH.

• Does the vacuum gauge indicate at least 11 in/Hg after six seconds but not longer than 60 seconds after switching the 4X4 mode switch to 4X4 HIGH?

Yes GO to E9.
No GO to E10.
E9 CHECK THE PVH SOLENOID FOR PROPER VACUUM OUTPUT LEVELS - 4X4 DISENGAGED NOTE: This step requires the use of a calibrated vacuum gauge that is accurate to within a minimum of 0.1 in/Hg. It is recommended that Pressure/Vacuum Module or equivalent 105-R0099 be used for this check. Observe the vacuum gauge while switching the 4X4 mode switch to 2WD.

• Does the vacuum gauge indicate between 5.85 and 7.1 in/Hg after six seconds but not longer than 30 seconds after switching the 4X4 mode switch to 2WD?

Yes REMOVE the vacuum gauge. RECONNECT all vacuum lines. TEST the system for normal operation. If the 4X4 system still does not operate properly, CLARIFY the customer concern and RETURN to Symptom Chart.
No GO to E10.
E10 RETRIEVE THE DIAGNOSTIC TROUBLE CODES (DTCS) NGS
Retrieve and document continuous DTCs.
Clear Continuous DTCs
GEM On-Demand Self-Test

• Are any DTCs retrieved?

Yes If DTC P1832, GO to E17 .

If DTC P1833, GO to E18 .

If DTC P1834, GO to E19 .

If DTC P1835, GO to E17 .

If DTC P1878, GO to E17 .

If DTC P1879, GO to E18 .

If DTC P1880, GO to E19 .

If DTC P1885, GO to E17 .
No GO to E11.
E11 CHECK FOR VOLTAGE TO THE PVH SOLENOID - CIRCUIT 298 (P/O) Disconnect PVH Solenoid C185
Measure the voltage between PVH solenoid C185-2, circuit 298 (P/O), and ground.

• Is the voltage greater than 10 volts?

Yes GO to E12.
No REPAIR circuit 298 (P/O). TEST the system for normal operation.
E12 CHECK THE GEM 4X4 ENGAGE SEQUENCE AND CIRCUIT 599 (PK/LG) - 2WD TO 4X4 HIGH Measure the voltage between PVH solenoid C185-2, circuit 298 (P/O), and PVH solenoid C185-1, circuit 599 (PK/LG) while switching the 4X4 mode switch to 4X4 HIGH.

• Is the voltage greater than 9 volts after three seconds but not more than 60 seconds after switching the 4X4 mode switch to 4X4 HIGH?

Yes GO to E13.
No GO to E17.
E13 CHECK THE GEM 4X4 DISENGAGE SEQUENCE AND CIRCUIT 599 (PK/LG) - 4X4 HIGH TO 2WD Measure the voltage between PVH solenoid C185-2, circuit 298 (P/O), and PVH solenoid C185-1, circuit 599 (PK/LG) while switching the 4X4 mode switch to 2WD.

• Is the voltage greater than 9 volts after three seconds but not more than 60 seconds after switching the 4X4 mode switch to 2WD?

Yes GO to E14.
No GO to E17.
E14 CHECK THE GEM 4X4 ENGAGE SEQUENCE AND CIRCUIT 77 (DB/Y) - 2WD TO 4X4 HIGH Measure the voltage between PVH solenoid C185-2, circuit 298 (P/O), and PVH solenoid C185-3, circuit 77 (DB/Y) while switching the 4X4 mode switch to 4X4 HIGH.

• Is the voltage greater than 9 volts after three seconds but not more than 60 seconds after switching the 4X4 mode switch to 4X4 HIGH?

Yes GO to E15.
No GO to E17.
E15 CHECK THE GEM 4X4 DISENGAGE SEQUENCE AND CIRCUIT 77 (DB/Y) - 4X4 HIGH TO 2WD Measure the voltage between PVH solenoid C185-2, circuit 298 (P/O), and PVH solenoid C185-3, circuit 77 (DB/Y) while switching the 4X4 mode switch to 2WD.

• Is any voltage indicated after three seconds after switching the 4X4 mode switch to 2WD?

Yes GO to E16.
No GO to E17.
E16 CHECK THE PVH SOLENOID COILS Measure the resistance between the PVH solenoid terminal 1 and terminal 3.

• Is the resistance between 90 and 115 ohms?

Yes GO to E20.
No REPLACE the PVH solenoid;TEST the system for normal operation.
E17 CHECK CIRCUITS 599 (PK/LG) AND 77 (DB/Y) FOR SHORTS TO GROUND PVH Solenoid C185
GEM C223
Measure the resistance between PVH solenoid C185-1, circuit 599 (PK/LG), and ground; and between PVH solenoid C185-3, circuit 77 (DB/Y), and ground.

• Are the resistances greater than 10, 000 ohms?

Yes GO to E18.
No REPAIR circuit 599 (PK/LG) and/or 77 (DB/Y). CLEAR the DTCs. TEST the system for normal operation.
E18 CHECK CIRCUITS 599 (PK/LG) AND 77 (DB/Y) FOR OPEN GEM C223
Measure the resistance between GEM C223-3, circuit 599 (PK/LG), and PVH solenoid C185, circuit 599 (PK/LG). Measure the resistance between GEM C223-7, circuit 77 (DB/Y), and PVH solenoid C185, circuit 77 (DB/Y).

• Are the resistances less than 5 ohms?

Yes GO to E19.
No REPAIR circuit 599 (PK/LG) and/or 77 (DB/Y). CLEAR the DTCs. TEST the system for normal operation.
E19 CHECK CIRCUITS 599 (PK/LG) AND 77 (DB/Y) FOR SHORTS TO POWER Measure the voltage between PVH solenoid C185-1, circuit 599 (PK/LG), and ground; and between PVH solenoid C185-3, circuit 77 (DB/Y), and ground.

• Is any voltage indicated?

Yes REPAIR circuit 599 (PK/LG) and/or 77 (DB/Y). CLEAR the DTCs. TEST the system for normal operation.
No REPLACE the GEM; the DTCs. TEST the system for normal operation.
E20 CHECK THE PVH SOLENOID FOR PROPER VACUUM OUTPUT LEVEL - 4X4 ENGAGED PVH Solenoid C185
Connect a vacuum gauge to the PVH vacuum line tee fitting and measure the vacuum while switching the 4X4 mode switch to 4X4 HIGH.

• Does the vacuum gauge indicate at least 11 in/Hg after six seconds but not longer than 60 seconds after switching the 4X4 mode switch to 4X4 HIGH?

Yes GO to E21.
No REPLACE the PVH solenoid; TEST the system for normal operation.
E21 CHECK THE PVH SOLENOID FOR PROPER VACUUM OUTPUT LEVELS - 4X4 DISENGAGED NOTE: This step requires the use of a calibrated vacuum gauge that is accurate to within a minimum of 0.1 in/Hg. It is recommended that Pressure/Vacuum Module or equivalent 105-R0099 be used for this check. Observe the vacuum gauge while switching the 4X4 mode switch to 2WD.

• Does the vacuum gauge indicate between 5.85 and 7.1 in/Hg after six seconds but not longer than 60 seconds after switching the 4X4 mode switch to 2WD?

Yes REMOVE the vacuum gauge. RECONNECT all vacuum lines. TEST the system for normal operation. If the 4X4 system still does not operate properly, CLARIFY the customer concern and RETURN to Symptom Chart.
No REPLACE the PVH solenoid; TEST the system for normal operation.
E22 CHECK THE RH SIDE WHEEL END FOR LEAKS Disconnect the RH wheel end vacuum line connector. NOTE: This step may require rapid pumping for up to 10 seconds. Connect a hand vacuum pump to the RH wheel end vacuum line connector and try to pull a vacuum to 15 in/Hg.

• Does the vacuum drop exceed 0.5 in/Hg in 30 seconds?

Yes GO to E24.
No GO to E23.
E23 CHECK THE LH SIDE WHEEL END FOR LEAKS Reconnect the RH wheel end vacuum line connector. Disconnect the LH wheel end vacuum line connector. NOTE: This step may require rapid pumping for up to 10 seconds. Connect a hand vacuum pump to the LH wheel end vacuum line connector and try to pull a vacuum to 15 in/Hg.

• Does the vacuum drop exceed 0.5 in/Hg in 30 seconds?

Yes GO to E24.
No VERIFY all vacuum line connections are OK. TEST the system for normal operation. If a vacuum leak is still present, REPLACE the PVH solenoid vacuum line. TEST the system for normal operation.
E24 CHECK THE CHASSIS VACUUM LINE FOR LEAKS Carefully disconnect the chassis vacuum line from the steel vacuum line. NOTE: This step may require rapid pumping for up to 10 seconds. Connect a hand vacuum pump to the steel vacuum line and try to pull a vacuum to 15 in/Hg.

• Does the vacuum drop exceed 0.5 in/Hg in 30 seconds?

Yes RECONNECT the chassis vacuum line to the steel vacuum line. GO to E25 .
No REPLACE the chassis vacuum line. TEST the system for normal operation.
E25 BUBBLE TEST THE RUBBER/STEEL VACUUM LINE INTERFACE WARNING: Do not use shop pressure when performing this check. CAUTION: Do not apply more than 2 psi to the vacuum lines when performing this check. Apply 2 psi continuous pressure to the vacuum wheel end output line.
Apply soapy water to the rubber/steel vacuum line fitting.

• Are air bubbles visible at the rubber/steel vacuum line interface?

Yes REPAIR the rubber/steel vacuum line interface. TEST the system for normal operation.
No GO to E26.
E26 BUBBLE TEST THE WHEEL END KNUCKLE VACUUM LINE FITTING WARNING: Do not use shop pressure when performing this check. CAUTION: Do not apply more than 2 psi to the vacuum lines when performing this check. Apply 2 psi continuous pressure to the vacuum wheel end input line.
Apply soapy water to the wheel end knuckle vacuum line fitting.

• Are bubbles visible at the wheel end knuckle vacuum line fitting?

Yes REPAIR the wheel end knuckle vacuum line fitting; TEST the system for normal operation.
No GO to E27.
E27 BUBBLE TEST THE HUBLOCK END AND HUBLOCK/WHEEL HUB INTERFACE WARNING: Do not use shop pressure when performing this check. CAUTION: Do not apply more than 2 psi to the vacuum lines when performing this check. Apply 2 psi pressure to the vacuum wheel end input line.
Apply soapy water to the hublock and hublock/wheel hub interface.

• Are bubbles visible at the hublock/wheel hub interface or at the hublock end?

Yes If bubbles are visible at the hublock/wheel hub interface, REPLACE the hublock/wheel hub O-ring; TEST the system for normal operation.

If bubbles are visible at the hublock end, REPLACE the hublock; TEST the system for normal operation.
No GO to E28.
E28 BUBBLE CHECK THE KNUCKLE/WHEEL BEARING INTERFACE WARNING: Do not use shop pressure when performing this check. CAUTION: Do not apply more than 2 psi to the vacuum lines when performing this check. Apply 2 psi pressure to the vacuum wheel end input line.
Apply soapy water to the knuckle/wheel bearing interface.

• Are bubbles visible at the knuckle/wheel bearing interface?

Yes REPLACE the wheel bearing/knuckle interface O-ring; No If equipped with 4WABS, GO to E29 .

If equipped with RABS, GO to E30 .
E29 BUBBLE CHECK THE ANTI-LOCK BRAKE SYSTEM (ABS) SENSOR WARNING: Do not use shop pressure when performing this check. CAUTION: Do not apply more than 2 psi to the vacuum lines when performing this check. Apply 2 psi pressure to the vacuum wheel end input line.
Apply soapy water to the ABS sensor.

• Are bubbles visible at the ABS sensor?

Yes REPLACE the ABS sensor O-ring; TEST the system for normal operation.
No GO to E30.
E30 BUBBLE TEST THE WHEEL BEARING OUTER SEAL WARNING: Do not use shop pressure when performing this check. CAUTION: Do not apply more than 2 psi to the vacuum lines when performing this check. Apply 2 psi pressure to the vacuum wheel end input line.
Apply soapy water to the wheel bearing outer seal.

• Are bubbles visible at the wheel bearing outer seal?

Yes REPLACE the wheel hub and bearing;TEST the system for normal operation.
No GO to E31.
E31 BUBBLE CHECK THE WHEEL END SHAFT SEAL Remove the two screws and slide the wheel end shaft seal cover back. WARNING: Do not use shop pressure when performing this check. CAUTION: Do not apply more than 2 psi to the vacuum lines when performing this check. Apply 2 psi pressure to the vacuum wheel end input line.
Apply soapy water to the wheel end shaft.

• Are bubbles visible at the wheel end shaft?

Yes REPLACE the wheel end shaft seal;TEST the system for normal operation.
No GO to E32.
E32 CHECK THE HUBLOCK FOR VACUUM LEAKS Remove the hublock assembly;
Connect hublock Vacuum Test Cap to the wheel end. Connect a hand vacuum pump to the wheel end vacuum supply hose and try to pull a vacuum to 10-12 in/Hg.

• Does the vacuum drop exceed 0.5 in/Hg in 30 seconds?

Yes GO to E33.
No REPLACE the hublock and O-ring;TEST the system for normal operation.
E33 CHECK THE WHEEL END KNUCKLE FOR VACUUM LEAKS Remove the 1/2 shaft retaining ring;
Remove the hub and bearing;
Remove the 1/2 shaft.

Install Seal Depth Set/Vacuum Test Cap to the wheel end knuckle.
Install Seal Replacer/CV Tester into the inboard wheel end seal. Connect a hand vacuum pump to the wheel end vacuum supply hose and try to pull a vacuum to 10-12 in/Hg.

• Does the vacuum drop exceed 0.5 in/Hg in 30 seconds?

Yes REPLACE the wheel end knuckle seal;TEST the system for normal operation.
No GO to E34.
E34 RECHECK THE WHEEL END KNUCKLE FOR VACUUM LEAKS - WHEEL BEARING SEAL REPLACED Replace and grease the wheel hub and bearing O-ring;
Install Seal Depth Set/Vacuum Test Cap to the wheel end knuckle. Install Seal Replacer/CV Tester into the inboard wheel end seal.
Connect a hand vacuum pump to the wheel end vacuum supply hose and try to pull a vacuum to 10-12 in/Hg.

• Does the vacuum drop exceed 0.5 in/Hg in 30 seconds?

Yes REPLACE the wheel hub and bearing; TEST the system for normal operation.
No System is OK.

Sounds like the TSB for the IWE solenoid, where water can get into the vacuum lines and not keep the IWE gear disengaged.

Right Click, save as :
http://my.voyager.net/~sscully/file_tsb06_08_15.pdf

The IWE ( Integrated Wheel Ends ) are held out with vacuum when the motor is running, Once the engine is turned off, and vacuum bleeds out of the system, the IWEs will lock again.

The other issue could be bad vacuum lines, where there is a crank in them from the IWE solenoid on the firewall down to the front wheels.

Until you have time to diagnose where the problem is with the IWE vacuum system ( TSB / Vacuum lines ) , either pull and pull the vacuum lines from the IWE and plug them ( front axle locked ) or drive in 4x4 so you do not round off the IWE gears.

Block diagram of the IWE system

If I read this correctly ( which I might not have, bit early for me ), the front drive shaft will engage ( from the transfer case ) but the front wheels are not engaged ?

If so, sounds like either the vacuum from the IWE ( Integrated Wheel End ) is not being released, or the IWEs have had an issue with part vacuum ( damage vacuum lines ) and the IWE gear is rounded off.

If you pull the vacuum lines at the IWEs ( there are 2 lines, 1 is the vacuum line, the other is the vent tube that routes up into the engine compartment and is not attached to anything ), the front wheel should engage ( might need a 5 * turn to mesh the gears ). With the vacuum lines off, jack up the front axle ( take precautions, chock the rear wheels, parking brake, jack stands, etc ) see if the front wheels are engaged ( turning one wheel should turn the other ). The option is to do this after the truck has sat over night, and the vacuum has been released out of the vacuum reservoir.

If the wheels turn correctly ( engaged ) I would think the contact plates in the transfer case are not making contact. Good starting point for this is the connector on the side of the transfer case, some times this gets gummed up, and the pins do not make good contact. The contact plates in the transfer case are used for a few things, one of them is to signal the IWE solenoids to release vacuum to the IWEs.

Operationally vacuum holds the IWE ( Integrated Wheel Ends ) out, and once vacuum is removed the spring engages the IWE.

Here is a black diagram of the IWE vacuum system

There are vacuum lines at the rear of the engine that t-off into different directions. These can become deteriorated with age and get mushy and collapse. The main culprit is underneath the battery tray. You'll have to remove the battery and the tray to get t it. The hose is connected to a vacuum actuator that controls the front axle engagement. It is always coming loose because of the sharp bend in the hose where it hooks up to the actuator. There is also a hose that runs down to the transfer case. While you're under there checking those vacuum hoses, go ahead and check the electrical connections at he front axle and the transfer case.

Its a vacuum opperated system. There is a vacuum line on the transmission but ufrortantly the transmission will not work correctly with this disconnected. That controls what is called an actuator its a vacuum moter its located under the battery tray and this pulls on the cable that makes it shift in and out of 4 wheel drive.Try disconnecting the cable at the actuator and pulling back away from the engine this may pull part # 9 the carrier conector out of the out put shaft part # 23 and disengage the 4 wheel so you can drive in 2 wheel with no side affects although you would have to replace # 9 or # 23 or bolth to make the 4 wheel work again but then again if you do this it may workthe gears just got bound up and it might work but i wouldn't push my luck with it until it was apart and could inspect the parts.

Be sure to put the truck in neutral, while engine is running, while you disengage from 4 wheel drive (low) to 4 wheel drive (high) and then finally to 2 wheel drive. It is critical to shift transmission into neutral when switching out of 4WD Low, as indicated in your owner's manual. Hopefully, this will help to FixYa problem!

Today and over the weekend .I too had the same problem. Took it to the dealer and they tested everything and could not find the problem. Did vac test on the lines, Test drove it with code tester to see if there was any problems . Checked the hubs... They replaced the IWE solenold. Just hope that is the fix and it didn;t damage anything else... Thanks for the above info!

There are issues with the 4x4 system I.w.e ends ingesting moisture/water into vacuum actuation system causing no 4x4 or ratcheting outboard I.w.e ends. (Even if you don't go 4x4'n ) pull off vacuum hoses @ I.w.e ends and check for moisture/water/rust also the I.w.e is not part of the wheel bearing itself It is the part on the axle side (inboard) of the spindle. (EVEN DEALERS CAT LISTED WRONG)Many shops just replace the wheel bearing side this may fix the symptom but not the true cause of damaged I.w.e. ! Check with a reputable dealer they should have info on this condition and repair procedure.


The integrated wheel end (IWE) system contains the following:

Vacuum reservoir
IWE solenoid
IWEs (spring loaded vacuum hubs)
Vacuum hoses
Check valve
The IWE system uses vacuum hubs that engage the front wheel hubs to the front half shafts or disengage the front wheel hubs from the front half shafts.

The IWE solenoid receives engine vacuum from the vacuum reservoir.

When the 4-wheel drive system is in 2WD mode, the 4x4 module (PCM)supplies a ground path to the IWE solenoid to apply vacuum to the integrated wheel ends (disengaging the front hubs from the front half-shafts). In 4WD mode, the 4x4 module (PCM) does not supply the ground path to the IWE solenoid, vacuum is not applied to the integrated wheel ends and an internal spring keeps the front hubs engaged to the front half-shafts.

Good luck and check the vacuum line, start with the simple. Keep me posted, be glad to get your 4wd working again.

shift into 4wd and move truck a couple of feet.
if light is still off, park truck block the wheels set the park brake jack right front wheel and try to hand spin the wheel if wheel doesn't turn 4x4 is functioning properly but there is a wiring problem use an ohmmeter to check the 4x4 switch wiring fuse and bulb
if wheel turns freely the front axle or transfer case is not engaged
attempt to hand spin the front driveshft if the driveshaft will spin the transfer case is not engaged check the transfer case shift linkage, problem is in linkage or transfer case internals
if the driveshaft will not spin the transfer case is engaged properly
with trnsmission in neutral or park start engine measure vacuum on the two vac lines at front axle shift motor . one line should have approx 20" vacuum. other line should have none
if no vacuum measured look for vac leak or bad vac switch
if both lines have vac look for a bad vac swithc or ruptured cad actuator diaphragm
if one line has 20" +- VAC
move transfer case lever to 2wd measure vac again lines should have swapped vac signals
if no vac switch bad or 4wd shift likage needs adjusting
if yes vac motor bad or stuck or shift fork stuck
remove vac shift motor from the axle attach vac lines to shift motor engage disengage 4wd
does shift motor plunger move at least 1/2 inch
no shift motor bad
yes check axle shift fork and vac motor for binging

are you setting still or driving when ingaugeing the 4 wheel drive if you are setting still try putting it in with vehicle moving if it does not light up steady in 4wd then it is not going in 4wd