Service Leveling System Message Due to Aftermarket Modifications

A Service Leveling System message or Speed Limited message on the Driver Information Center (DIC) on some 2021 Tahoe, Suburban, Yukon and Escalade models may be due to aftermarket modifications. If an aftermarket lowering kit is installed on these models, it may cause an incorrect vehicle ride height variance, which may be indicated by a decreased distance between the top of the tire and the fender well. (Fig. 16)

 

Fig. 16

 

If these DIC messages are displayed, inspect the vehicle ridge height being altered. Refer to the Trim Height Inspection procedure in the appropriate Service Information. Trim height is a predetermined measurement relating to vehicle ride height and incorrect trim heights can cause the vehicle to bottom over bumps, damage the suspension components, and show symptoms similar to wheel alignment problems. Always check the trim heights when diagnosing suspension concerns and before checking the wheel alignment. (Fig. 17)

 

Fig. 17

 

An aftermarket lowering kit may cause premature wear to the air suspension components, tires and CV joint. It also may affect proper headlamp aiming.

Once the suspension has been found to be lower than the factory specifications, check for installed aftermarket adjustable suspension height sensor links. (Fig. 18)

 

Fig. 18

 

The original factory suspension height sensor links are not adjustable. (Fig. 19)

 

Fig. 19

 

Aftermarket adjustable height sensor links that are incorrectly adjusted side-to-side or not secured properly will result in inaccurate height sensor readings. (Fig. 20)

 

Fig. 20

 

In addition, the aftermarket adjustable height sensor links also will change the angle of the rear axle drive shaft due to the suspension being lowered. (Fig. 21)

 

Fig. 21

 

Any damage or performance concerns that occur as a result of these vehicle modifications may not be covered under the new vehicle limited warranty. Refer to the Bulletin #09-00-89-016 for additional information about suspected tampering or vehicle modifications.

Refer to #PIT5854 for more information.

 

– Thanks to Scott Fibranz

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