Why does the Highlander AWD change to 2AWD and fail to start?
3 Answers
If the four-wheel drive system malfunctions, it could be due to damage to the multi-plate clutch or its control system. A computer diagnostic scan is required to check for fault codes. If fault codes appear in the engine system, ABS system, etc., the instrument display will show AWD changing to 2WD. Only a computer diagnostic scan can accurately identify the issue. Here are more details about the Highlander: 1. Exterior: The Highlander features triangular headlights, a hexagonal front grille with angular design, an integrated Toyota emblem, thick chrome accents, fog lights embedded with chrome trim, and a slightly forward-leaning front fascia, giving the front end a stylish and three-dimensional appearance. 2. Powertrain: The Highlander offers two powertrain options—a 3.5L V6 engine paired with a 5-speed automatic transmission and a 2.7L L4 engine paired with a 6-speed automatic transmission. Both engines are equipped with Toyota's exclusive Dual VVT-i technology, ACIS variable intake system, roller rocker arm structure, and other advanced technologies.
Speaking of the Highlander failing to start after switching from AWD to 2WD, I've actually encountered this issue. As an owner, I believe the most common causes are battery problems or sensor malfunctions. When switching drive modes, the vehicle's computer may detect abnormal signals and activate a safety lock to prevent startup. My suggestion is to first check the battery voltage: if it's below 12 volts, charge it immediately or replace it. Then inspect the relevant fuses in the engine compartment box to see if they're blown. If the drive mode sensor is dirty or loose, it can easily trigger false alarms—you can clean the switch position with a soft cloth. Additionally, resetting the system is quite effective: disconnect the negative battery terminal for 10 minutes, reconnect it, and try starting again. In daily use, develop the habit of ensuring the vehicle is completely stopped before switching drive modes, and avoid frequent operation during rain or snow. Poor handling of this issue affects driving safety—if you can't fix it yourself, take it to a professional shop for inspection. Spending a little money now can save you major trouble later.
From my experience in car modification, failure to start after switching driving modes is mostly caused by transient electronic system faults. I frequently disassemble automotive circuits and find the Highlander's ECU is sensitive during mode transitions—it locks out startup at the slightest signal conflict. Check all connectors for tightness, especially the drive module joints near the chassis. Battery aging is an accomplice, particularly noticeable in winter's low temperatures—measure voltage and address immediately if insufficient. Using an OBD2 scanner to read error codes can precisely identify whether it's the mode sensor or other components causing trouble. Sometimes software bugs can be fixed by disconnecting the battery for a reset. Don't skimp on regular maintenance—clean sensors to prevent dust and grime buildup, and periodically test the ignition system to ensure coils and spark plugs function properly. In short, keep detailed vehicle status records and prioritize preventive measures.
