I would like to see that if you dont mind.
There are many nuances to diagnosing and troubleshooting the IWE. The simplest checks can be done with the truck on the ground and no special tools. These are my own checks I devised after reading the workshop manual, but they are not necessarily part of the workshop manual. To avoid confusion, I listed these below as steps A and B. Again, steps A and B can be done without any tools, but only checks the basic operation of the overall IWE system. It is insufficient for diagnosing a single faulty component. For further testing you'll need a vacuum pump and vacuum pressure gauge (0-30 inches Hg). A cheap vacuum pump/pressure gauge combo can be had for
around $60 at AutoZone.
"My" Steps:
A. Place truck in PARK and transfer case in 2H. All four wheels should be firmly on the ground. Bleed off any residual vacuum pressure from the IWE hub actuators by disconnecting the vacuum lines located at the 12 o'clock position where the CV axle meets the hub. There are two nipples coming off the hub actuator/IWE--one is larger than the other, so you shouldn't have to worry about labeling or getting them mixed up. The vacuum lines appear vulcanized together, similar to the positive and negative conductors of a strand of speaker wire. It's not important to note which is which for now, but the larger is the vacuum source while the smaller is an atmospheric pressure vent. (NOTE: With a cold truck that has not been started for a few hours--or perhaps even several minutes--you should not need to bleed off vacuum pressure). In this state, the IWE/hubs should be LOCKED. This can be verified by attempting to rotate the CV axle by hand. To ensure you are getting enough leverage to turn the axle shaft, grab the CV axle at its largest diameter, such as at the inboard CV joint housing where the CV shaft splines engage the differential. The axle should not move. Check both the LT and RT side in this manner.
B. If you disconnected the the vacuum lines from either the LT or RT hub actuators/IWE's reconnect them now. Start the truck. Ensure the truck is/remains in 2H. Once started, engine vacuum should release the hub actuators/IWE's. Similar to above, attempt to rotate the CV axle by hand. Again, to ensure you are getting enough leverage to turn the axle shaft, grab the CV axle at its largest diameter, such as at the inboard CV joint housing where the CV shaft splines engage the differential. This time, the axle should rotate freely indicating the the hub is UNLOCKED.
If it does not perform as indicated, something is wrong. These next steps will tell you what is wrong. The below follows step numbering convention used in the workshop manual:
Workshop Manual Steps:
T2 CHECK THE IWE SOLENOID OUTPUT VACUUM IN 2H
NOTE: The engine must be idling during the following steps to supply vacuum to the IWE solenoid.
• Start the engine.
• Disconnect the output vacuum line at the IWE solenoid while having the vacuum supply attached to the solenoid.
• With the engine running and the in 2H mode, measure the vacuum at the output port of the solenoid.
• Is the vacuum greater than 254 mm (10 In) Hg?
--> Yes? GO to T7; No? GO to T3
T3 CHECK THE IWE SOLENOID INPUT VACUUM
• Disconnect the supply vacuum line at the IWE solenoid.
• With the engine still running, measure the supply line vacuum to the IWE solenoid.
• Is the vacuum greater than 254 mm (10 in) Hg?
--> Yes? Replace IWE solenoid and retest; No? GO to T4
T4 CHECK SOURCE VACUUM TO THE VACUUM RESERVOIR
• Disconnect the source vacuum line from the vacuum reservoir.
• With the engine still running, measure the source vacuum being supplied to the vacuum reservoir.
• Is the vacuum greater than 254 mm (10 In) Hg?
--> Yes? GO to T5; No? repair/replace vacuum line and retest
T5 CHECK THE VACUUM RESERVOIR
• Ignition OFF.
• Disconnect the vacuum line from the vacuum reservoir.
• Connect a hand vacuum pump to the source vacuum port on the vacuum reservoir and apply 508 mm (20 in) Hg of vacuum.
• Does the vacuum maintain or drop less than 25 mm (1 in) Hg per minute?
--> Yes? GO to T8; No? repair/replace source vacuum line and retest
T6 CHECK THE ONE-WAY VACUUM CHECK VALVE
• NOTE: The check valve is between the IWE solenoid and the vacuum reservoir.
• Connect the vacuum lines to the IWE solenoid.
• Connect a hand vacuum pump to the IWE solenoid vacuum line at the vacuum reservoir and apply 508 mm (20 in) Hg of vacuum.
• Does the vacuum maintain or drop 1 less than 25 mm (1 in) Hg per minute?
--> Yes? No apparent discrepancy exists in IWE system; No? replace vacuum lines AND check valve and retest
T7 CHECK THE IWE VACUUM SYSTEM
• Ignition OFF.
• Disconnect both vacuum lines from the IWE solenoid.
• Using a hand vacuum pump, apply 508 mm (20 in) Hg of vacuum to the IWE system through the apply vacuum circuit.
• Observe the vacuum reading.
• Does the vacuum maintain or drop less than 25 mm (1 in) Hg per minute?
--> Yes? Reconnect vacuum line and GO to T11; No? GO to T8
T8 CHECK THE RH IWE LEAK RATE
• With the vehicle in NEUTRAL, position it on a hoist.
• Disconnect the vacuum lines from the larger port on the RH IWE
• Apply 508 mm (20 in) Hg of vacuum to the RH port and observe vacuum reading.
• Does vacuum maintain or drop less than 25 mm (1 in) Hg per minute?
--> Yes? GO to T10; No? replace RH IWE
T8 CHECK THE RH IWE LEAK RATE
• Disconnect the vacuum lines from the larger port on the LH IWE
• Apply 508 mm (20 in) Hg of vacuum to the LH port and observe vacuum reading.
• Does vacuum maintain or drop less than 25 mm (1 in) Hg per minute?
--> Yes? GO to T10; No? Replace LH IWE
T10 CHECK THE IWE VACUUM SUPPLY TUBE
• Disconnect both vacuum lines from the IWE solenoid.
• Plug both LH and RH IWE vacuum lines. Apply 508 mm (20 in) Hg of vacuum to the IWE apply vacuum circuit and observe the vacuum reading.
• Does the vacuum maintain or drop less than 25 mm (1 in) Hg per minute?
--> Yes? Go to T11; No? replace vacuum lines as necessary and retest
T11 CHECK THE IWE VACUUM SUPPLY AT EACH IWE IN 2H
• Connect a hand-held vacuum gauge to the LH vacuum supply tube.
• NOTE: The engine must be idling during the following steps to supply the vacuum required for the IWE to engage and disengage.
• Start the engine.
• Switch to 2H mode while observing the vacuum gauge.
• Repeat these steps for the RH IWE.
• Are the vacuum readings greater than 254 mm (10 In) Hg?
--> Yes? GO to T12; No? replace vacuum lines as necessary and retest
T12 CHECK THE LH IWE VACUUM LINE FOR AN OBSTRUCTION
• Ignition OFF.
• Disconnect both vacuum lines from the IWE solenoid.
• With the vehicle in NEUTRAL, position it on a hoist
• Disconnect the vacuum line at the LH IWE.
• Connect a hand vacuum pump to the LH IWE vacuum line and attempt to draw a vacuum on the line.
• Did the hand vacuum pump draw a vacuum on the LH IWE vacuum line?
--> Yes? Replace vacuum line and retest; No? Connect the vacuum line to the LH IWE and GO to T13
T13 CHECK THE RH IWE VACUUM LINE FOR AN OBSTRUCTION
• Disconnect the larger vacuum line at the RH IWE.
• Connect a hand vacuum pump to the RH IWE vacuum line and attempt to draw a vacuum on the line.
• Did the hand vacuum pump draw a vacuum on the RH IWE vacuum line?
--> Yes? Replace vacuum line and retest; No? Connect vacuum line to the RH IWE and GO to T14
T14 CHECK THE LH IWE OPERATION
• Ignition OFF.
• Connect a hand vacuum pump with gauge to the larger port of the LH IWE.
• Observe the LH halfshaft while rotating the LH front tire. Apply between 152 and 203 mm (6 to 8 in) Hg of vacuum and release the vacuum to manually disengage and engage the LH IWE
• Did the LH IWE disengage between 152 and 203 mm (6 to 8 in) Hg and engage when the vacuum is released?
--> Yes? GO to T15; No? Replace LH IWE
T15 CHECK THE RH IWE OPERATION
• Connect a hand vacuum pump with gauge to the larger port of the RH IWE.
• Observe the RH halfshaft while rotating the RH front tire. Apply between 152 and 203 mm (6 to 8 in) Hg of vacuum and release the vacuum to manually disengage and engage the LH IWE
• Did the RH IWE disengage between 152 and 203 mm (6 to 8 in) Hg and engage when the vacuum is released?
--> Yes? GO to Pinpoint Test U; No? Replace RH IWE.
Pinpoint Test U is a complete 4wd functional test and requires an advanced scan tool that can access more than just DTC codes. If you have one of these, then you would have already sprung for the workshop manual as well, so I won't bother posting.
