What causes the flashing of the 4LO light on a Prado?
3 Answers
The flashing of the 4LO light on a Prado is caused by engine misfiring leading to excessively high exhaust temperatures, poor operation of individual cylinders, or overly rich fuel mixture resulting in poor combustion. Common solutions include checking the condition of spark plugs and high-voltage wires; inspecting whether the cylinder pressure is normal, and if not, examining whether the valves and cylinder gasket are damaged; and checking the fuel injection system. Below is an introduction to common faults in automotive electrical systems: 1. Engine not turning: When the starter switch is engaged, the starter motor spins freely, but the engine does not turn. The fault mainly lies in the starter's control and operating components or the starter's one-way clutch. 2. Poor instrument operation: Malfunctioning of various instruments on the dashboard. The causes of instrument failures include short circuits in the combination instrument's power supply or grounding circuits, damage to sensors and their wiring, or damage to the instrument cores. The causes of warning light failures on the dashboard include bulb failure, loose lamp sockets, or damage to alarm sensors and their wiring. 3. Poor lighting operation: Malfunctioning of various lights on the vehicle. Possible causes include bulb failure, loose lamp sockets, or poor operation of the lighting circuit system, mainly due to faults in the power supply or wiring, switches, and plugs in the circuit.
When I was off-roading with my Prado before, I encountered a situation where the 4LO light was flashing. The car was parked on a slope, and I wanted to engage low-range four-wheel drive to climb up, but the indicator light started flashing continuously. After checking the manual, I realized that switching to 4L in the Prado must be done when the vehicle is completely stopped, and it requires shifting to neutral and stepping on the brake. I was in a hurry that time and didn’t follow the procedure properly, so the system detected an error and triggered the flashing light alarm. Actually, this is usually caused by improper operation, such as attempting to switch while moving or not firmly shifting to neutral. However, it could also be due to a problem with the transmission system’s sensors, like a faulty differential lock position sensor or loose wiring connections. Later, I checked the fuse box myself, and everything seemed fine. I had to take it to a professional shop for a diagnostic scan, which revealed a minor fault in the control unit. Resetting the system fixed the issue. Paying attention to these details during regular maintenance can prevent unexpected failures at critical moments, especially when off-roading—safety is always the top priority.
As a car enthusiast who often helps friends with car repairs, I find the flashing 4LO light on the Prado quite common. First, consider whether the shift wasn't properly engaged—for example, if you didn't come to a complete stop or didn't press the brake before switching to 4WD low mode. Hardware issues could also be the culprit; loose or dirty wiring connectors might trigger false alarms, and a faulty differential lock module could cause the light to flash. Problems with the electronic control unit are another possibility, as unstable sensor signals might lead the system to misjudge. I recommend starting with some basic checks: bring the vehicle to a complete stop, turn the key off and restart, shift into neutral, and try engaging 4L again. If the light continues to flash, don't push your luck—check the fuses and relays immediately to ensure the power supply is intact. For the long term, regularly cleaning the underbody dust covers can help prevent such minor issues, as 4WD systems are quite delicate and proper maintenance is key to peace of mind.
