Some vehicles may exhibit intermittent or no 4X4 engagement, even while the 4X4 lamp is illuminated, and/or a “clunking” noise may be heard while shifting into 4X4 on the fly. This may be caused by:
• Electrical connection at the vacuum solenoid
• Vacuum connections
• Front axle shaft retainers not seated
• Vacuum sealing in wheel ends
• Hub locks
• Front driveline component damage
Diagnose and repair the vehicle using the following Pulse Vacuum Hub Lock (PVH) Diagnostics and Repair Procedure.
THE PVH 4X4 SYSTEM IS LOCKED AND UNLOCKED USING TWO (2) DIFFERENT VACUUM LEVELS TO ACTIVATE 4X4 SOLENOID. THE HIGH VACUUM ENGAGES THE HUB LOCK SYSTEM, WHILE THE LOW, REGULATED VACUUM LEVEL DISENGAGES THE HUB LOCK SYSTEM. THESE ACTIONS ARE NOT LINKED WITH THE 4X4 LAMPS. THEREFORE, WHEN DIAGNOSING A 1998 RANGER 4X4 ISSUE, 4X4 INSTRUMENT PANEL LAMP ILLUMINATION AND FRONT DRIVE SHAFT ROTATION DO NOT INDICATE THAT THE SYSTEM IS OPERATING PROPERLY (AS IN PRIOR MODEL YEAR RANGER 4X4s). THE FRONT HUB SYSTEM MUST BE SERVICED USING THE FOLLOWING PROCEDURE.
SIMPLY REPLACING THE FRONT HUB LOCKS IS NOT A PROPER FIX FOR MOST PVH 4X4 SYSTEM ISSUES. MOST ROOT CAUSES OF NON-ENGAGEMENTS AND NOISE ARE FOUND ELSEWHERE IN THIS NEW 4X4 SYSTEM. THE PROPER HUB LOCK REMOVAL TOOLS AND PROCEDURES NEED TO BE USED TO AVOID DAMAGING THE PARTS. THESE PARTS ARE TO BE REUSED IF ALL ATTACHING LEGS ARE INTACT. REPLACE HUB LOCKS ONLY IN THE EVENT OF BREAKAGE OF THE PLASTIC BODY OR RETAINING LEGS (SEE THE 1998 RANGER WORKSHOP MANUAL, PAGE 204-01B-4).
PULSE VACUUM HUB LOCK (PVH) DIAGNOSTICS AND REPAIR PROCEDURE:
1. Place the vehicle in 4X2 mode and drive for 1.6 kilometers (1 mile) at road speeds.
2. Stop the vehicle, turn the wheels to full lock, and exit the vehicle. By hand, manually attempt to rotate both the front drive axle shafts in the hub ends. If the shafts are NOT locked, proceed to Step 3, If the shafts are locked, proceed to Step 5.
3. Shift into 4X4 HIGH and drive around slowly for 1.6 kilometers (1 mile). Be sure 4X4 HIGH light illuminates.
4. Perform tight steering turns on dry pavement and check for front wheel hop/binding. If wheel hop/binding occurs, the front hubs did engage and the system is fully functional. If not, follow Steps 5-11.
5. Be sure the solenoid electrical connector and all solenoid vacuum connections are secured properly to the 4X4 solenoid valve located below RH head lamp on the frame.
6. Be sure all vacuum connections are seated on top of both front frame rails and into the front wheel ends.
7. Be sure all vacuum connections are seated at the vacuum reservoir canister and back to the engine manifold.
8. Check both the RH and LH front axle shaft’s axial free play at the outboard shaft joint prior to removing any parts. Perform this step by grabbing the outer metal portion of the shaft joint and pulling back and forth toward and away from the front differential. The free play is excessive (greater than 1/8″), then the front axle shaft retainer ring(s) is not properly seated or is missing.
THE PVH 4X4 SYSTEM USES FRONT AXLE SHAFT RETAINER RINGS (A PLASTIC PART WITH A METAL CIRCLIP) TO HOLD THE HALFSHAFTS FROM MOVING INWARD TOWARD THE DIFFERENTIAL. IF A RING IS MISSING OR NOT SEATED, THE SHAFT FACE WILL LOSE CONTACT WITH THE MAIN KNUCKLE VACUUMSEAL (DIRT EXCLUDER/VACUUM SEAL) AND LOSS OF 4X4 FUNCTION MAY OCCUR. ALSO, THE FRONT WHEEL END MAY INGEST MUD, WATER, AND OTHER DEBRIS, DUE TO INSUFFICIENT PROTECTION FROM THE ENVIRONMENT. THIS ISSUE MAY CAUSE AN INTERMITTENT 4X4 FAILURE TO ENGAGE OR DISENGAGE, BECAUSE THE SHAFT MAY MOVE IN AND OUT AGAINST THE SEAL DURING CERTAIN ROAD EVENTS, ALLOWING FOR INTERMITTENT VACUUM SEALING.
9. If excessive axial free play is observed, remove the hub lock, remove and discard the wheel hub O-ring, and discard the axle shaft retainer. Pull the front axle shaft carefully out and away from the knuckle assembly and clean and inspect the main knuckle vacuum seal and the axle shaft metal surfaces. If any parts appear worn, corroded, or contaminated, replace them as necessary per the Workshop Manual, Pages 204-01B-27 and 28. Replace the retainer ring, and wheel hub O-ring with grease, and reuse the hub lock if not broken or cracked (refer to the Workshop Manual, Pages 204-01B-4, 5, and 8 through 12).
10. Check both the RH and LH wheel end vacuum sealing (as assembled) with a hand vacuum pump per the Workshop Manual, Pages 308-07A-95 through 103. If you find a leak, repair per the pinpoint vacuum leak test recommendations. Note the following KEY aspects of the PVH wheel end:
a. When removing a hub lock, always use the correct tools and reuse the hub lock unless broken or cracked.
b. ALWAYS replace and regrease (using High Temperature 4X4 Wheel Bearing And Axle Grease (E8TZ-19590-A)) the 0.035 wheel hub O-ring seal when a hub lock is removed and reassembled. This is a sealing point for the hub vacuum system.
c. The front axle shaft retainers MUST be fully seated in their grooves and oriented with the metal circlip facing outward. Never reuse a front axle shaft retainer.
d. If the front axle halfshaft is pulled out of the wheel end, clean and inspect the main vacuum seal and the halfshaft metal surfaces. If any damage to either part is present, replace the part.
ALWAYS REGREASE THE MAIN VACUUM SEAL WITH 3 GRAMS (0.1 OZ) OR MORE OF HIGH TEMPERATURE 4X4 WHEEL BEARING AND AXLE GREASE (E8TZ-19590-A) PER THE WORKSHOP MANUAL, PAGES 204-01B-27 AND 28.
e. If the wheel hub and wheel bearing pack are ever unbolted from the knuckle, replace and regrease the 0.044 O-ring in the wheel bearing groove. This is a sealing point for the hub vacuum system.
NOTE: NEVER ATTEMPT TO REMOVE OR REPAIR THE IN-BOARD WHEEL BEARING RETAINER NUT. REFER TO THE WORKSHOP MANUAL, PAGES 204-01B-6 THROUGH 8.
f. In addition to the wheel hub 0.035 O-ring, the wheel bearing 0.044 O-ring, and the main knuckle vacuum seal, other sealing points in the wheel end assembly include:
• the steel vacuum line into the knuckle
• the wheel bearing seals
• the Anti-lock Brake System (ABS) sensor on the wheel bearing (if equipped)
Follow the pinpoint vacuum leak tests for proper diagnostic procedures.
g. Upon reassembling the front wheel end system, ALWAYS recheck the vacuum sealing per the Workshop Manual, Page 308-07A-95.
11. Upon completion of all repairs, road test the 4X4 system function by carefully following Steps 1-4.
DURING ALL DIAGNOSTICS (HOIST OR ROAD TESTS), NOTE THAT THE ENGAGEMENT VACUUM PULSE LASTS FOR APPROXIMATELY 50 SECONDS. WHEN DIAGNOSING THE TRUE STATE OF THE HUB LOCK SYSTEM, LET THIS AMOUNT OF TIME PASS BEFORE CHECKING FOR ACTUAL SHAFT ENGAGEMENT. THE DISENGAGEMENT VACUUM TIMER LASTS FOR APPROXIMATELY 15 SECONDS. AGAIN, LET THIS AMOUNT OF TIME PASS BEFORE CHECKING FOR ACTUAL SHAFT DISENGAGEMENT.
THE ENGAGEMENT VACUUM FROM THE SOLENOID IS THE HIGH VACUUM LEVEL AND CORRESPONDS TO THE MAXIMUM CHARGED LEVEL, FROM THE ENGINE MANIFOLD, IN THE VACUUM CANISTER. THE DISENGAGEMENT VACUUM FROM THE SOLENOID IS REGULATED AND SHOULD MEASURE BETWEEN 6 AND 7″ HG OF VACUUM. THE HUB LOCKS ENGAGE AT VALUES AROUND 7-1/2 TO 8-1/2″ HG.
4X4 SHIFT-ON-THE-FLY “CLUNKS”:
When a customer states the vehicle exhibits noise when shifting into 4X4 HIGH on the fly, certain areas should be diagnosed. Remember that 4X4 instrument panel light illumination and front driveshaft/front axle shaft rotation are not the sole indicators of 4X4 engagement. Target areas to examine here are:
• Transfer case clutch relay and wiring connections
• Transfer case shift motor (related Generic Electronic Module (GEM) codes)
• Front driveshaft CV joint damage
• Front axle bolts missing or loose
• Front axle half shaft CV joint damage
NOISY HUB LOCKS ARE FREQUENTLY A SYMPTOM OF OTHER 4X4 SYMPTOM ISSUES AND ARE SELDOM THE CAUSE FOR SHIFT NOISE. IN THESE CASES, SIMPLY REPLACING THE HUB LOCKS DOES NOT FIX THIS CONCERN.
4X4 LOW RANGE OPERATION
The 4X4 LOW function can only be engaged or disengaged by doing the following:
1. Zero vehicle speed.
2. Foot on brake.
3. Transmission in Neutral (clutch depressed).
4. Move the 4WD control to the 4X4 LOW position.
Many 1998 Ranger 4X4 customers have reported 4X4 LOW issues when they have not met all four requirements. Review these requirements with customers to determine whether they have followed the proper engagement procedures.
OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS: Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage.