Drive Engine Run-Up (DERU) Test

WARNING: This page is about a different car, the 2018 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Block all wheels, set the parking brake and firmly apply the service brake to reduce the risk of vehicle movement during this procedure. Failure to follow these instructions may result in serious personal injury.

To carry out this procedure, proceed as follows:

Block the front and rear wheels.
Apply the parking brake and the service brake.
Install a tachometer.
Shift the transmission into DRIVE, and increase and decrease the engine rpm between an idle to approximately 2, 000 rpm. Note the engine rpm and, if possible, determine the vibration frequency.
Repeat the test in REVERSE.
If the vibration/noise is duplicated when carrying out this test, inspect the engine and transmission or transaxle mounts.
If the symptom is definitely engine speed-related, carry out the Engine Accessory Test to narrow down the source.
If the source of the symptom has been identified as a result of this test, proceed to the appropriate information for further diagnosis and repair. If the source has not been identified, continue with the road test.