Headlights Dimming More Than They Should?

[ToyotaDomo]

Right guys and girls,

How about this one for you all to think about. I have a 2006 1.8L avensis and at night when I touch the brake or turn on the indicators, the headlights dim for a second or so by a lot compared with any other car that I have ever driven. I mentioned it to the main dealer at the time when I bought it they say that it is normal. Over time I have become used to it. I am wondering is it a feature of the car to protect itself against any sudden electical loads or is it a fault. By the way it can be any major elec load that when turned on while the lights are on, will dim them for a second or so.

[Q.S.]

Right guys and girls,

How about this one for you all to think about. I have a 2006 1.8L avensis and at night when I touch the brake or turn on the indicators, the headlights dim for a second or so by a lot compared with any other car that I have ever driven. I mentioned it to the main dealer at the time when I bought it they say that it is normal. Over time I have become used to it. I am wondering is it a feature of the car to protect itself against any sudden electical loads or is it a fault. By the way it can be any major elec load that when turned on while the lights are on, will dim them for a second or so.

Seems to be fairly normal on the Avensis, my 02 plate does it too when any extra electrical load is applied. Probably just a delay in the alternators voltage/current regulator.

[ToyotaDomo]

Right guys and girls,

How about this one for you all to think about. I have a 2006 1.8L avensis and at night when I touch the brake or turn on the indicators, the headlights dim for a second or so by a lot compared with any other car that I have ever driven. I mentioned it to the main dealer at the time when I bought it they say that it is normal. Over time I have become used to it. I am wondering is it a feature of the car to protect itself against any sudden electical loads or is it a fault. By the way it can be any major elec load that when turned on while the lights are on, will dim them for a second or so.

Seems to be fairly normal on the Avensis, my 02 plate does it too when any extra electrical load is applied. Probably just a delay in the alternators voltage/current regulator.

Thanks mate for the news. It seems that it is normal then and nothing for me to worry about.

[Heidfirst]

doesn't do it on my 2007 model.

sounds like an electrical problem to me (poor earth?).

[Jamesbelfast]

A poor earth at one of the rear light clusters could cause such problems. As the dimming occurs when the brake is dperessed might be a clue. If it were mine I would be checking out the multi-connectors to the rear lamps.:)

[Q.S.]

A poor earth at one of the rear light clusters could cause such problems. As the dimming occurs when the brake is dperessed might be a clue. If it were mine I would be checking out the multi-connectors to the rear lamps.:)

A poor earth on the rear lights wont affect the headlamps (different circuit) and would only affect the lights in the rear cluster. If it's like mine, any load, such as electric windows, heating fan (full speed) brake lights etc. dims the headlamps momentarily until the voltage reg catches up with the loading.

[cmia]

A poor earth at one of the rear light clusters could cause such problems. As the dimming occurs when the brake is dperessed might be a clue. If it were mine I would be checking out the multi-connectors to the rear lamps.:)

A poor earth on the rear lights wont affect the headlamps (different circuit) and would only affect the lights in the rear cluster. If it's like mine, any load, such as electric windows, heating fan (full speed) brake lights etc. dims the headlamps momentarily until the voltage reg catches up with the loading.

Q.S is right,

However ...

Putting in attitional and bigger earthcables has made the problem less prominent on my D4D

Earth to Body

Body to engine

The Diesels have a larger alternator.

[ToyotaDomo]

A poor earth at one of the rear light clusters could cause such problems. As the dimming occurs when the brake is dperessed might be a clue. If it were mine I would be checking out the multi-connectors to the rear lamps.:)

A poor earth on the rear lights wont affect the headlamps (different circuit) and would only affect the lights in the rear cluster. If it's like mine, any load, such as electric windows, heating fan (full speed) brake lights etc. dims the headlamps momentarily until the voltage reg catches up with the loading.

Q.S is right,

However ...

Putting in attitional and bigger earthcables has made the problem less prominent on my D4D

Earth to Body

Body to engine

The Diesels have a larger alternator.

Ok Guys good information, thanks. I will try to check out the earth from engine to body and Battery to body. over the next week or so and let u know if it makes any difference

[Q.S.]

A poor earth at one of the rear light clusters could cause such problems. As the dimming occurs when the brake is dperessed might be a clue. If it were mine I would be checking out the multi-connectors to the rear lamps.:)

A poor earth on the rear lights wont affect the headlamps (different circuit) and would only affect the lights in the rear cluster. If it's like mine, any load, such as electric windows, heating fan (full speed) brake lights etc. dims the headlamps momentarily until the voltage reg catches up with the loading.

Q.S is right,

However ...

Putting in attitional and bigger earthcables has made the problem less prominent on my D4D

Earth to Body

Body to engine

The Diesels have a larger alternator.

Ok Guys good information, thanks. I will try to check out the earth from engine to body and Battery to body. over the next week or so and let u know if it makes any difference

Agree with cmia, problem could be reduced by improving the connection/current flow between the alternator/battery and the body.

[avensis t22]

New Battery and your problem solved

[Q.S.]

New battery and your problem solved

Sorry can't agree. Electrics run from alternator when the engine is running. The alternator should produce enough current (at charging voltage) to supply ALL the vehicle electrics and have enough in reserve to charge the Battery as well. Problem is due to voltage drop (as previously described).

[KenMavor]

Had similar problems and did nowt and then the car wouldn't start one afternoon.

I would check the general condition of the earth lead from Battery to chassis as well as checking the actual

condition of the connection between the Battery poles and the connectors. I reckon that the bad weather

and over the last few months had caused the Battery terminals to oxidise badly and hence the

current was having to work extra hard to actually flow. Battery was not getting charged as efficiently

as it should do and the alternator was having to work harder to drive the current around the circuit.

Cleaning the battery poles and the connectors to get a clean, solid connection solved the problem of bad current

flow (symptoms were lights dipping a lot when more drain on the power) and then the car not starting.

Worth a shot before a brand new battery required.

[ToyotaDomo]

OK guys, thanks for all the responses. All very helpful. So what I did was to take out Battery and clean all earthing points and then Battery terminals and Battery connections. It may have made a slight improvement but not much. I think that it is just a design flaw in the alternator, or maybe a spike protections system in the alternator. Only Toyota knows. I give up

[Jamesbelfast]

OK guys, thanks for all the responses. All very helpful. So what I did was to take out battery and clean all earthing points and then battery terminals and battery connections. It may have made a slight improvement but not much. I think that it is just a design flaw in the alternator, or maybe a spike protections system in the alternator. Only Toyota knows. I give up

Has the alternator voltage output been checked??:)

[Jamesbelfast]

OK guys, thanks for all the responses. All very helpful. So what I did was to take out battery and clean all earthing points and then battery terminals and battery connections. It may have made a slight improvement but not much. I think that it is just a design flaw in the alternator, or maybe a spike protections system in the alternator. Only Toyota knows. I give up

Has the alternator voltage output been checked??:)

[ToyotaDomo]

OK guys, thanks for all the responses. All very helpful. So what I did was to take out battery and clean all earthing points and then battery terminals and battery connections. It may have made a slight improvement but not much. I think that it is just a design flaw in the alternator, or maybe a spike protections system in the alternator. Only Toyota knows. I give up

Has the alternator voltage output been checked??:)

Yeah man did all that and even had toyota dealer check it out when it was under warranty. They say that it happens on all avensis models. Makes you wonder.

[Q.S.]

OK guys, thanks for all the responses. All very helpful. So what I did was to take out battery and clean all earthing points and then battery terminals and battery connections. It may have made a slight improvement but not much. I think that it is just a design flaw in the alternator, or maybe a spike protections system in the alternator. Only Toyota knows. I give up

Did you get the earth connection from the engine to body/battery too? If so, maybe it's as well to give up