A ‘service all-wheel drive system’ message is a sign of an issue with the all-wheel drive system. The issue could have been set off by something as little as installing an incorrect tire size or a low battery. A worn or contaminated rear differential fluid is also something you should check. A bad control module and corroded terminals are also possible culprits.
All-Wheel Drive System and “Service AWD System” Warning
The AWD system transfers power between all four wheels to maintain vehicle traction. It uses a driveshaft to distribute the engine power between the front and rear wheels.
A ‘service all-wheel drive system’ warning indicates that the AWD system is disabled. And only the front wheels will be powering the vehicle.
The warning could stay on or flash intermittently. But it is usually accompanied by a beeping sound. And it is common but not limited to General Motors vehicles.
Causes and Possible Fixes of the ‘Service All Wheel Drive System’ Message
The AWD warning is often activated because of an issue with the rear differential system. But, the breakdown of other components could also set off the warning.
Low battery
You should start by inspecting the battery power whenever you notice the AWD warning. The AWD system relies on the battery charge to stay operational. And anytime the battery voltage drops below 9 volts, the AWD system disables the rear wheels. It also activates the “service all wheel drive system” warning to alert the driver.
And if a defective or low battery indeed triggered the warning, a system scan will reveal a C0550 error code. The system will record the diagnostic code either as a stored or pending DTC.
Solving this problem is quite straightforward. If the battery is bad, replacing it will solve the problem. But if it is still in good condition, you should inspect your electrical system for a parasitic draw.
Tire
Something as minute as the tire can also turn on the “service all wheel drive system” warning. Installing an incorrect tire size or not replacing all four tires simultaneously can prompt the message. Both instances confuse the traction control system, causing premature wear of the drivetrain.
The AWD system will trigger the “service all wheel drive system” message to alert the driver. Thus, the correct tire size must be installed at all times. And when replacing any tire, you must change all four, so you don’t confuse the traction control system.
Corroded connectors
A corroded rear differential harness or control module connector could activate the warning. The rear differential system has a control module in charge of the system’s operation. The rear differential harness connects to the control module connector.
Exposing the wiring harness or control module connector to water creates corrosion. The corrosion gradually eats away the connector pins causing the breakdown in connection.
The break in transmission triggers the AWD system warning. A good preventive measure is to slather some di-electric grease on the connectors. But if the corrosion has done the damage, you’ll have to replace the connectors.
Faulty control module
The bad control module is another culprit that can set off the “service all wheel drive system” light. Like the connectors, exposing the control module to liquid can short it.
Clean the control module immediately after it comes in contact with water. And slather some di-electric grease on it to prevent it from shorting out. Once the control module goes bad, the only solution is to replace the module.
Overheated clutch control assembly
An overheated rear differential clutch assembly can also trigger the warning. The clutch control assembly transfers torque to the rear axle. The clutch assembly has a sensor that monitors the temperature to ensure it is within the range of -40°C to +120°C.
The AWD system disables the rear wheels anytime the clutch assembly overheats. This triggers the “Service All Wheel Drive System” on the dashboard. The rear wheels will reactivate when the temperature is back within range. The warning will also go away after a couple of drive cycles.
Contaminated rear differential fluid
The rear differential is divided into the clutch assembly and the ring gear segment. A seal separates both segments and prevents their different fluids from mixing.
General Motors recommends replacing the fluids every 150,000 miles. The AWD warning may pop up when the fluids become dirty after an extended period of use.
You will also get a warning if the seal separating both segments fails. The seal’s failure allows the fluid from both segments to mix. This disrupts the proper functioning of the rear differential system.
Replacing the fluids at the recommended interval will help keep the system running. Moreover, servicing the fluid is much cheaper than replacing warped components. For the rear differential seal, you’ll have to replace it once it fails.
How to Tackle the ‘Service All-Wheel Drive System’ Warning
You should scan your vehicle for error codes to narrow down the source when you get the warning. A basic OBD scanner cannot pull up trouble codes for a ‘service all-wheel drive system’ warning.
You’ll need a scanner that can communicate with the AWD system. Once you detect the cause of the problem, you can proceed to solve it. But you should know that dealing with an AWD system issue can be complex, even for a regular DIYer. So. you may want to use the services of a mechanic to avoid causing more damage to the system.
Final thoughts
The vehicle switches to two-wheel drive the instant the AWD warning pops up on the dashboard. The warning is often set off because of an issue with the rear differential system. But other factors, such as using incorrect tire size or a low battery, can also trigger the warning.
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