Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

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Drive Engine Run-Up (DERU) Load Test

To carry out this test, proceed as follows:
^ Block the front and rear wheels.

WARNING: BLOCK THE FRONT AND REAR WHEELS, AND APPLY THE PARKING BRAKE AND THE SERVICE BRAKE, OR INJURY TO PERSONNEL CAN RESULT.

CAUTION: Do not carry out the Engine Load Test for more than five seconds or damage to the transmission or transaxle can result.

^ 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 2000 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 concern is definitely engine speed-related, carry out the Engine Accessory Test to narrow down the source. Engine Accessory Test
^ Proceed as necessary.