1994 gmc suburban 4wd front diff whining

[961kyle]

wondering if anyone has had issues with the front diff whining when engaged, just bought the vehicle and 4wd worked fine with no problems the first couple times now it goes in but whines, get louder and faster and the faster i go, any ideas/

[Molson02536]

Check your front differential fluid level, if not service your differential fluid.

Differential, Front......GL-5 ALL TEMPS......80W-90 In cold climates when excessive shift effort is required to shift into 4WD GM part no. 12345836 or equivalent may be used in front differential.
Do not use synthetic lubricant in axles using RTV sealant. Synthetic lubricant will chemically attack RTV sealant. American Axle has only approved the use of Synthetic
Lubricant 75W-90 GM part no. 12378261, as follows:
a. All 8.6 inch rear axles are compatible.
b. All 9.5 inch rear axles built before mid-February 1998 (RTV sealant used to seal cover pan) are not compatible
c. All 9.5 inch rear axles built after mid-February 1998 (equipped with cover pan & gasket) are compatible.
d. All 10.5 inch rear axles built prior to March 3, 1999 are compatible if axle shafthub RTV sealer is replaced with GM gasket part no. 327739.

Capacity, Differential, Front..........1.7 liters Torque, Fill Plug 18 ft/lbs Drain Plug 18 ft/lbs

Keep me posted, and hoping it's not your differential or actuator.

[aaron.bennett]

Hey i'm having a similar problem with my 2001 GMC sierra. bought it used and 4 wheel worked fine. now this winter it whines pretty loud. i havent used it unless necessary. let me know how the suggestions work for you.

thanks

[961kyle]

changed fluid today, still making the same noise, now it sort of clunked it which it never did before and the light flashed once than came on which it never did before, also before when i took it out of 4wd it came right out with no delay today i had to come to a complete stop before it went back to 2wd, anymore ideas?

[Molson02536]

On the full size, the front actuator is electric, not vacuum.

When in 4wd mode, a switch on top of the transfer case conducts 12 volts out to the actuator. Wire #50 (brown) is the 12v feed, and it conducts to the light blue wire (#900) to the actuator.
When shifted out of 4wd, the switch opens up and no voltage goes to the actuator.

I'll assume it is the actuator, if the plug to the actuator is getting 12 volts when in 4wd.
The way this actuator works, is it is a sealed chamber that gets heated by voltage. When it heats, the pin in the end swells and pushes a shift fork in the front differential. The shift fork engages a spline on the passenger side of the differential, and boom! you have 4WD.

GM offered an upgrade to this actuator that is a motor instead of a heated device. However, it requires a small harness addition, a spacer, and a new actuator. It is about a $150 to $200 option.

Good luck. The actuator is usually the problem 90% of time but recheck all of the wire harness just to maker sure there is no short before replacing any parts. The actuator may not be fully engaged or disengaged and the fork to the spline may be what is causing the whining or grinding noise you hear.

88-UP C/K ACTUATOR UPGRADE
VEHICLE SERVICED: 1994 CHEVROLET FULL SIZE
PURPOSE: IMPROVE AXLE CONNECT ENGAGEMENT TIME AND
COMPONENT RELIABILITY.

SYMPTOMS: NO FRONT DRIVE AXLE ENGAGEMENT WHEN SHIFTED INTO 4X4.

Obtain the following GM part numbers:
(1) 26060073 Actuator
(1) 88959465 Harness/Spacer Kit

[ISLANDER914]

Molsen, what do you know about the indicating lights on the dash push buttons for 2WD, 4H, 4L and Nuetral on a 1999 suburban. My 4 wheel drive is fully functional but I notice that when in 2 wheel drive the indicating light goes dim sometimes,and sometimes is just off. It comes on when I start the vehicle and while driving it comes on and off. The guy at AAmco said it is could just be the switch on the dash. And how do you go to nuetral anyway, this is my first push button 4WD, I am used to levers. It has a N light but it only lights when you first start the vehicle. Any thoughts would be great, Thanks.

[Molson02536]

The manual only says you have to be less than 3 mph or so and the transmission in neutral to shift to 4LO. Below is the information from the manual.

You can choose among four driving settings:

AUTO 4WD (which i don't think you have, but will help others): This setting is ideal for use when road conditions are variable. When driving your vehicle in AUTO 4WD, the front axle is engaged, but the vehicle's power is sent to the rear wheels. When the vehicle senses a loss of traction, the system will automatically engage four-wheel drive. Driving in this mode results in slightly lower fuel economy than 2HI.

(2HI): This setting is used for driving in most street and highway situations. Your front axle is not engaged in two-wheel drive. This setting also provides the best fuel economy.

(4HI): Use 4HI when you need extra traction, such a on snowy or icy roads or in most off-road situations. This setting also engages your front axle to help drive your vehicle. This is the best setting to use when there is snow drifts, but keep in mind that you will accelerate faster then stopping. So don't speed in snow or icy conditions.

(4LO): This setting also engages your front axle and delivers extra torque. You may never need 4LO. It sends maximum power to all four wheels. You might choose 4LO if you are driving off-road in deep sand, deep mud, deep snow and climbing or descending steep hills.

Caution: Shifting the transfer case to Neutral can cause the vehicle to roll even if the transmission is in P (Park). You or someone else could be seriously injured. Be sure to set the parking brake before placing the transfer case in Neutral.

NEUTRAL: Shift the vehicle's transfer case to NEUTRAL only when towing your vehicle.

ndicator lights in the switches show which setting your transfer case is in. The indicator lights will come on briefly when you turn on the ignition and one will stay on. If the lights do not come on, you should take your vehicle to your dealer for service. An indicator light will flash while the transfer case is being shifted. It will remain illuminated when the shift is complete. If for some reason the transfer case cannot make a requested shift, it will return to the last chosen setting. If the SERVICE 4WD message stays on, you should take your vehicle to your dealer for service.

Shifting into 4HI or AUTO 4WD
Press and release the 4HI or AUTO 4WD switch. This can be done at any speed (except when shifting from 4LO), and the indicator light will flash while shifting. It will remain illuminated when the shift is completed.

Shifting into 2HI
Press and release the 2HI switch. This can be done at any speed (except when shifting from 4LO).

Shifting into 4LO
To shift to 4LO, the ignition must be in RUN and the vehicle must be stopped or moving less than 3 mph (4.8 km/h) with the transmission in NEUTRAL (N). The preferred method for shifting into 4LO is to have your vehicle moving 1 to 2 mph (1.6 to 3.2 km/h). Press and release the 4LO switch. You must wait for the 4LO indicator light to stop flashing and remain illuminated before shifting your transmission in gear.

Notice: Shifting the transmission into gear before the Four-Wheel Drive Low indicator light has stopped flashing could damage the transfer case. To help avoid damaging the vehicle, always wait for the Four-Wheel Drive Low indicator light to stop flashing before shifting the transmission into gear.

It is typical for your vehicle to exhibit significant engagement noise and bump when shifting between 4LO and 4HI ranges or from NEUTRAL with the engine running. If the 4LO switch is pressed when your vehicle is in gear and/or moving, the 4LO indicator light will flash for 30 seconds and not complete the shift unless your vehicle is moving less than 3 mph (4.8 km/h) and the transmission is in NEUTRAL (N). After 30 seconds the transfer case will shift to 4HI mode.

Shifting Out of 4LO
To shift from 4LO to 4HI, AUTO 4WD or 2HI your vehicle must be stopped or moving less than 3 mph (4.8 km/h) with the transmission in NEUTRAL (N) and the ignition in RUN. The preferred method for shifting out of 4LO is to have your vehicle moving 1 to 2 mph (1.6 to 3.2 km/h). Press and release the 4HI, AUTO 4WD or 2HI switch. You must wait for the 4HI, AUTO 4WD or 2HI indicator light to stop flashing and remain illuminated before shifting your transmission into gear.

Same notice as putting your 4WD in to 4LO. If the 4HI, AUTO 4WD or 2HI switch is pressed when your vehicle is in gear and/or moving, the 4HI, AUTO 4WD or 2HI indicator light will flash for 30 seconds but will not complete the shift unless your vehicle is moving less than 3 mph (4.8 km/h) and the transmission is in NEUTRAL (N).

Shifting into NEUTRAL
To shift the transfer case to NEUTRAL do the following:

Make sure the vehicle is parked so that it will not roll.
Set the parking brake.
Start the vehicle or turn the ignition to RUN.
Connect the vehicle to the towing vehicle.
Put the transmission in NEUTRAL (N).
Shift the transfer case to 2HI.
Simultaneously press and hold the 2HI and 4LO buttons for 10 seconds. The red NEUTRAL light will come on when the transfer case shift to NEUTRAL is complete.
Shift the transmission to REVERSE (R) for one second, then shift the transmission to DRIVE (D) for one second, or FIRST (1) for vehicles equipped with a manual transmission.
Turn the ignition to LOCK.
Place the transmission shift lever in PARK (P), or FIRST (1) for vehicles with a manual transmission.
Release the parking brake prior to towing.

Shifting Out of NEUTRAL
To shift out of NEUTRAL:

Set the parking brake and apply the regular brake pedal.
Shift the transmission to NEUTRAL (N) and turn the ignition to RUN with the engine off.
Press the button for the desired transfer case shift position (2HI, 4HI, AUTO 4WD or 4LO).
After the transfer case has shifted out of NEUTRAL the red light will go out.
Release the parking brake.
You may start the engine and shift the transmission to the desired position.
Excessively shifting the transfer case into or out of the different modes may cause the transfer case to enter the shift protection mode. This will protect the transfer case from possible damage and will only allow the transfer case to respond to one shift per 10 seconds. The transfer case may stay in this mode for up to three minutes.

Also note with the transfer case you have with the three button without the Auto 4WD or AWD. Do not drive the suburban on dry pavement, only the AWD and Auto button can be used on dry pavement.

AS for your light going on and off on the switch, there is a bad connection or faulty bulb. Or there is a short on the wire harness to your front actuator which is common as mentioned to Kyle with his problem. The switch it self went bad on my jimmy and one bored day, I replaced the transfer case with a AWD Transfer case. The only bad thing about the AWD transfer case is doing the fluid change on it every 30,000 miles if not less and having the front tires wear out. Enjoy your Suburban and hope this helps you and everyone else.

[plein-gaz]

est-ce normal que la lumière qui indique le changement du 4x4 reste toujour allumer a la même endroit, est-ce une autre lumière qui allume pas?

[Molson02536]

Lumière sur le commutateur 4X4 indique quelle est la position la boîte de transfert est activée. Si 4HI voyant est allumé, puis 4RM doit être active, l'indication des 2RM aura la lumière sur les 2RM. Démarrage de la banlieue s'allume toute la lumière sur l'interrupteur puis s'éteignent et ensuite indiquer à 2RM ou 4RM que la banlieue est po Bonne chance et espérons que cette aide, désolé mon français n'est pas si grande. Plein-gaz

With the change of the Chanel:

Light on the 4X4 switch indicates what the transfer case position is on. If 4hi light is on then 4wd should be active, indication of 2wd will have the 2wd light on. Starting the suburban will light all light on switch then will go off and then indicate 2wd or 4wd that the suburban is in. Good luck and hope this helps, sorry my french is not that great. Plein-gaz

[plein-gaz]

salut!

peut importe sur lequel je le met, y a toujour la même indication qui allume..est-ce une lumière qui est fausse, ou bien un défaut mécanique du transfert case?.....merci!