Computers/Controls - Vehicle Test Drive Precautions

Don't Test-Drive With MIL On or D Indicator Blinking

NOTE:
This article applies to '01-03 3 2CLs, '01-06 MDXs, '99-04 3.5RLs, '05-06 RLs, '02-06 RSXs, '99-03 3.2TLs, '04-06 TLs, and '04-06 TSXs.

When the PCM detects a problem that turns on the MIL, starts the D indicator blinking, or both, it can revert to a backup mode or "limp home" mode. This mode differs depending on the A/T design, the cause of the malfunction or DTC, or both. When you test-drive a vehicle, make sure you first clear all A/T DTCs. You can't evaluate the A/T if the MIL is on, the D indicator is blinking, or both are on.

In backup mode, some A/Ts let you manually shift while others let you shift only to certain gears that apply to its particular backup mode. Here are some common symptoms you get in backup mode:

^ Harsh upshifting and downshifting

^ Vehicle starts in 2nd gear and then shifts to 4th gear

^ Vehicle starts in 2nd gear and then shifts to 3rd gear

When an A/T is in backup mode, service clients commonly complain about low power or lousy acceleration because the vehicle starts in 2nd or 4th gear.