Rear Motor in Prius?

There is an autolevelling servo motor in the headlights that adjusts the aim of the headlights according to the pitch of the car. I believe this uses a sensor attached to the rear suspension that measures its compression.

If that sensor had failed, I believe you would be getting a warning light on the dashboard.

There's no magic autolevelling suspension system on the Prius to keep the car itself level (it's not a Citröen). The suspension is entirely conventional (MacPherson strut front, torsion beam rear).

Even with autoaiming, the system needs to be manually calibrated to a "neutral" position. This is no different from a normal headlight system - the aim is performed with the car unloaded except for the driver and fuel. The autoaim then adjusts from that reference point.

 

either way it should be covered under warranty. likely it's just the baseline adjustment is out like KMO said.

 

You talked to one of the dealer drones who has only a vague idea of what is in the automobile. There is no motor that changes the pitch of the car.

What all cars sold in the USA with HID headlights are required to have is an automatic headlight leveling system. The car has "sensors" attached to the suspension to evaluate whether the car is pitched up or down and there are motors in the headlight assemblies to adjust the headlights to match. This is so a heavy load in the back doesn't pitch the headlights up and blind other drivers. If I remember correctly, you can see the rear sensor if you take the driver's side rear wheel off (it is attached to the spring assembly).

In Europe, some cars have a manually adjustable system that lets the driver adjust the headlights up or down. Alternatively, they just need to be adjusted correctly.

The USA system generally means the headlights can only be properly adjusted at the dealer. They use a scan tool to command the system to its midpoint before doing the manual adjustment to the headlamp. This preserves the maximum automatic adjustment span.

If I had to guess, your car may have a broken or disconnected sensor. The car thinks the back end is high and is commanding the headlights to pitch upwards.

- Tom

 

I'm guessing he said "gear motor". HID headlghts have a sensor and a motor to keep them level. It doesn't re-level the whole car. I'd bring it in to your shop and have a tech look at it. It's a good idea to meet your local Prius Tech and ask him if you can show him your issue. You'll get a more personal service experience that way. There are specs and tools for measuring and adjusting light position.

If you stop on a hill and wait 5 seconds or so, you should see your lights adjust.

 

Here is the sensor:
[attachmentid=2047]

Here is the adjustment:
[attachmentid=2048]

 

Take it in and have the dealer fix it under warranty, PriusKid. There have been some defective level sensors, which caused all kinds of weird aiming. The dealer can dertermine if the sensor is functioning correctly (probably not) and then aim the headlights when the sensor is fixed.

 

Huh? Did this happen recently? I've never heard of such a requirement. Both my 02 Nissan Maxima that I sold recently and 04 350Z both came w/factory HID lights. Neither have any such system. I'm sure if it had it, it'd have been mentioned in the manual and touted as a feature. A friend's 04 Mazda RX-8 w/HIDs did have such an autoleveling system though.

 

No, he's right. ALL cars sold in the US with HID lighting are required to have the self-leveling feature. This requirement has been there from the start. My other car is a 2000 Audi A8 with HID lights (first I saw them) and it has the self-leveling feature too.

 

Can you find some credible references on the net regarding this? This sure isn't touted as a feature on the current HID equipped Maximas, Altimas, or 350Zs. HID equipped Muranos have a "manual levelizer".

http://www.consumerreports.org/cro/cars/ma...03/overview.htm mentions "In January 2003, Perel told a conference of researchers that new rules may reduce the maximum height for all headlights. NHTSA may also require self-leveling, which adjusts HID beams based on load so they don’t point upward when the vehicle is full. Self-leveling is required in Europe, where HID headlights are currently on 25 percent of all vehicles.

We think NHTSA should take the following steps:...
Adopt the European standard requiring HID headlights to be self-leveling."

The Audi A8 you cite is a VERY expensive car and is German.

 

I am not surprised that it is not mentioned in a car manual. Not everyone would consider it a "marketing" feature.

A lot of people think that it adjusts the lights as you go up and down hills - it doesn't. It measures spring compression of the rear suspension relative to the front and adjusts only for vehicle stance. It is intended to adjust for load variations and perhaps suspension sag with age. As I understand it, the requirement has been in place when the DOT regulations were changed to allow HID lamps.

- Tom

 

As a side not, on a much more expensive car like the Infiniti M35/45, auto leveling HIDs are mentioned as an option at http://www.infiniti.com/content/0,,action-...-123084,00.html.

"High Intensity Discharge (HID) xenon low-beam headlights with automatic leveling
Adaptive Front lighting System (AFS)."

I think you guys are wrong to claim that they have always been required in the US given the Consumer Reports article and given the type of hits I see at http://www.google.com/search?q=hid+levelin...=&start=10&sa=N where people are calling on NHTSA to require auto leveling.

When I get a chance, I'll check my 350Z's service manual to see if it mentions anything about that. I'm 90% sure it does NOT have it.

 

I don't see any Infinity choice of HID lamps without the leveling, all the premium cars I've seen have always listed auto leveling as part of the specs when you got the HID option.

Nevertheless, I also did a Google search on variations on the topic and see that you are correct that auto leveling is not required in the USA. If the Wikpedia article is to be believed, HIDs are required to be auto leveling in Europe (EU) and that auto leveling is permitted but not required in the USA. I guess that the "required" that I always saw in the Audi discussion groups was an incorrect statement of the EU requirement applied to the USA.

Given the legal climate in the USA, I'm surprised it is not a requirement. Thanks for the correction. I guess most manufacturers decide to leave it in for US since they have to have it for Europe.

- Tom

 

In Europe, HID headlamps are also required to have headlight washers.

 

Which is why they don't sell the Prius with HIDs here.

 

Go look at the specs and features touted for the 350Z, Maxima and Altima at nissanusa.com. They all can come w/HIDs, depends on the trim. They don't discuss leveling at all for those cars.

Also look at
http://www.nissannews.com/infiniti/2006veh...i_m/specs.shtml
http://www.nissannews.com/infiniti/2006veh...q45/specs.shtml
http://www.nissannews.com/infiniti/2006veh.../fx/specs.shtml
http://www.nissannews.com/infiniti/2006veh...x56/specs.shtml
http://www.nissannews.com/infiniti/2006veh...dan/specs.shtml
http://www.nissannews.com/infiniti/2006veh...upe/specs.shtml

The QX56 does have auto-rear leveling suspension since it's a large SUV. The only vehicle that Infiniti mentions has any sort of auto-leveling for the lights is the M35/45 [and arguably the QX56].

I just checked the service manual in the LT (lighting section) for my 04 350Z. There's no discussion of any leveling system and the section on aiming the lights doesn't discuss it either.