Why Is My Honda Pilot VTM-4 Warning Light On?

The Honda Pilot's all-wheel-drive system is pretty clever, with variable torque distribution between its front and rear axles, as well as between the left- and right rear wheels. It generally works well and ensures strong traction on difficult roads - but some issues have been reported over the years.

The first two generations of AWD-equipped Honda Pilots featured the earlier iteration of this system, named VTM-4, while the latest i-VTM4 system is found in the third-generation Pilot. Their modes of operation are very similar, though, with the newer i-VTM4 essentially just adding more intelligence to the rear-axle torque distribution algorithms for improved agility and better stability in extreme driving conditions. But what if something goes wrong?

So, what does the VTM-4 light on a Honda Pilot mean, and does it indicates a dire prognosis? First, let's look at what VTM-4 is. VTM-4 is the acronym for Variable Torque Management 4-wheel drive system, denoting the electronically-controlled 4-Wheel-Drive system Honda uses in their higher-end SUVs. Don't confuse this with Honda's "Real Time AWD" as used in earlier CR-V and HR-V models because that system lacks the VTM-4's clever rear differential and does not have the same torque-distribution abilities as the full-fat VTM-4 or i-VTM4 systems. So, if the VTM-4 light on your Honda Pilot comes on, it indicates a problem in this system.

However, it's important to note that there is a clear distinction between the gauge-display-mounted VTM-4 (or i-VTM4) warning light, and the confirmation light inside the dashboard-mounted VTM-4 switch, to the left of the audio system. The VTM-4 warning light in the Honda Pilot's instrument cluster should only illuminate when starting up the engine, following which it should extinguish within a second or so. Thereafter, it's supposed to remain off, even if the clever rear differential is called to action. If the VTM-4 cluster warning light switches on while driving, it indicates something amiss with the rear differential operation, which can be due to a surprisingly wide array of possible causes.

The confirmation light in the switch indicates that "VTM-4 Lock Mode" has successfully been engaged. However, the confirmation light should only be illuminated when you have purposely engaged Lock mode, and the button should be pressed again to disengage Lock as soon as it is no longer necessary or when returning to hard surfaces. Doing so will turn off the confirmation light, and all will be well.

Reasons why the VTM-4 light on a Honda Pilot could illuminate vary; from easily-remedied issues with the wiring harness or sensors to being part of a much larger set of problems, including:

• The pressure or temperature sensors for the rear differential could be defective
• Rear differential oil level may be low due to a leak or a prior overheating incident
• Rodents may have damaged the vehicle's wiring harness
• There could be a serious engine- or emission-control-related problem

First-generation (2003-2008) Honda Pilots will most likely illuminate the VTM-4 warning light due to insufficient differential fluid or a sensor error, with 2004- and 2005 model year examples reportedly being most prone to these ailments.

Second- and third-generation Pilots (2009-2015 and 2016-2022 model years, respectively) share these possible causes but add the possibility that there may be engine- or emission-control problems, in which case the AWD system will automatically disengage and switch the warning light on. This appears to be most prevalent on examples built in 2011, 2012, and 2013 - roughly in line with the model years of those Honda Pilots, which are most prone to emission-control issues as well.
Click here to read more about Honda Pilot 2nd Generation.

Whereas a warning light that stays on is less serious, if the light is flashing, you should stop driving as soon as possible. According to the owner's manual, a flashing VTM-4 warning light on a Honda Pilot means that you should immediately pull over, slot the transmission into Park, and let the engine idle until the VTM-4 light stops flashing.

If it continues flashing even after an extended idling period, shut down the engine and call a towing service to take your Pilot to a reputable workshop on a flatbed truck. In this case, a flashing Honda Pilot VTM-4 light indicates a serious problem in the rear differential, and driving on is likely to cause further damage.

A flashing Honda Pilot VTM-4 light indicates a problem where Honda advises urgent attention from a technician, but if a VTM-4 warning light stays on, it simply means that the AWD system has been deactivated due to a problem. In this instance, the control system has isolated the fault by disengaging the torque take-off from the front transaxle and opening the VTM-4's clutches, turning your AWD Honda Pilot into an FWD-only car.

If the light is on all the time, you can continue driving, but with due consideration for the fact that the AWD system is not available and that it will need attention very soon. A proper diagnostic effort and effective repairs are, unfortunately, the only way to effectively deal with an illuminated VTM-4 light on a Honda Pilot.

The cure for an illuminated VTM-4 warning light varies depending on the problem that triggered the light in the first place. Two of the possible remedies are simple DIY jobs, which are well within the abilities of a mildly-capable home mechanic. Other problems are more demanding and will need professional hands to resolve. Here is a checklist to follow if you're wondering how to turn off a Honda Pilot VTM-4 light:

1. Check for low VTM-4 fluid levels: If the VTM-4 rear differential is simply running low on fluid, the solution would be to replace it. Honda recommends VTM-4 fluid replacement every 7,500 miles and because it is, unfortunately, improbable that an older Pilot will have been treated to fresh VTM-4 fluid in the recent past, this is a common source of VTM-4 problems. Replace the fluid, and see if the warning light is still shining.
2. Check the sensors in the VTM-4 unit: There are a number of sensors in the VTM-4 unit which could cause the VTM-4 warning light to illuminate, with the fluid temperature sensor being the most-common culprit. Problems with this sensor are especially likely in vehicles from areas where road salt is used because this failure can usually be traced to corrosion of the wiring terminals. It's an easy fix and involves removing a small cover plate, unbolting and removing the sensor, and replacing it with a new one. Remember to cover the electrical terminals with grease to prevent a recurrence of the corrosion problem, then replace the cover plate and clear the error code from the OBD-II system.
3. Check for wiring harness faults: The Honda Pilot features enviro-friendly, soy-based electrical insulation, and vermin seem to find this a very tasty snack. There have been numerous reports of the VTM-4 warning light illuminating through nothing more serious than a few chewed wires, but the damage could be extensive enough to warrant professional attention to repair properly. If this is the problem, the VTM-4 warning light may illuminate along with other dashboard warning lights because rats aren't choosy regarding which system's harnesses they destroy.
4. Consider engine problems and emission control system failures: These are the issues you really don't want to encounter because they may quickly lead to an expensive engine repair. You will most likely notice this problem when the Honda Pilot's VTM-4 light and check engine light illuminate at the same time, and the on-board diagnostic system may show the P3400 error code in confirmation. The problem originates in the VCM (Variable Cylinder Control) system fitted to 2006-on first-generation Pilots and all second- and third-generation models. The VCM is responsible for shutting down the rear cylinder bank under low-load conditions, but has an unfortunate side-effect of causing excessive oil consumption. If this happens, the spark plugs eventually get fouled up with soot, leading to misfires. As soon as the engine's control system detects repeated misfires, it goes into limp-home mode and completely disengages the AWD system, illuminating both the Check Engine Light and the VTM-4 warning light on the Honda Pilot.

If the problem in a Honda Pilot's VTM-4 is related to a sensor issue in the rear differential assembly, the repair will be surprisingly affordable because an OEM temperature sensor can be had for less than $70, and it's an easy DIY replacement exercise. VTM-4 fluid is also quite well-priced, costing less than $30 for a gallon, and replacing it is also a straightforward DIY task.

Repairs for the oil consumption/emission control issue range from complete engine replacement in extreme cases to simply reprogramming the engine control unit and fitting a new set of spark plugs, but this all depends on the severity of the oil consumption problem. This issue needs professional attention, and may even be covered by a class-action lawsuit or Honda's eight-year engine warranty extension. Check with your dealership whether your Pilot is covered for this well-known issue, but remember that this problem did not lead to a recall, so only cars with active warranties will qualify for Honda's extended cover.

Lastly, if the VTM-4 or i-VTM4 unit itself needs to be replaced, expect to pay upwards of $3,700 for the assembly, excluding oil or labor to fit it. This alone is enough reason to pull over when the VTM-4 warning light starts flashing! As far as the VCM issue is concerned, check with your Honda dealership if your Pilot is included in the warranty extension for this matter, because, apart from sensor- or wiring failures, emission control malfunctions are the main reason why a Honda Pilot's VTM-4 warning will light up.