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head lights dim when touch brakes/turn blow motor on

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head lights dim when touch brakes/turn blow motor on

  #1  
Old 01-20-2016, 09:46 PM
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Default head lights dim when touch brakes/turn blow motor on

Hi!

Camry 2000, 2.2 L, 5 speed, 250,000 miles. Battery is 2 months old, 12.6V.
Original alternator with new brushes and voltage regulator. 14.5 V. Florida car: no rust.
Checked for loose ground, did not find any, not sure where to find them all. Found a crack on the terminal clamp on negative battery terminal and fixed this. This problem is also reported on Saturn.

1. When I drive the car with the headlights and radio on, and press or touch the brakes, one or more of the following may or may not happen:
a. radio stops working for a few seconds.
b. clock resets to 1:00
c. engine skips a beat.
d. headlights turn dim to aprox 60%
After a second or two radio restarts, headlights return to 80%.
When release the brakes: 100%
2. When I drive the car with the headlights and radio on, and turn the heat/cold fan suddenly from 0 to max, same as above.
3. When I drive the car with the headlights and radio on, and switch from low to high beam, same as above.
4. When I park the car, engine OFF, headlights and radio on, can not reproduce the problem: touch the brakes, turn the blow motor on, high-low beam, no problems.
This is why I replaced the alternator brushes, they were almost completely gone.
This is why I replaced the voltage regulator, no luck: problem still here.
I checked the voltages:
AA. Engine off. Battery 12.6
BB. Engine on: Battery terminals: 14.5, alternator 14.5 (copper stud on the side of alternator: this is were the DC goes out to the battery)
CC. A friend presses the brake: Battery drops to aprox 13.6 for a moment, then goes back to 14.5. Second time press brakes: no effect.
DD. A friend presses the brake: Alternator drops to aprox 13.6 for a moment, than returns to 14.5.

Many people search for loose ground wire: I exclude this, because battery alone does not show the problem. And because the problem does not happen always. See below.
I exclude the battery, because battery alone does not show the problem and cranks the engine always.
If and only if the alternator is spinning, providing extra voltage, the problem reveals itself.

If attempt is made to repeat tests 1, 2 or 3, to reproduce the problem, can not: The car should idle or drive around for a min or 2 or more, before the problem can be reproduced.
Looks like some capacitor gets discharged, dimming the headlights, and then it takes some time to recharge again. Is it possible some relay or car computer?


 
  #2  
Old 01-20-2016, 11:30 PM
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Location: Ipswich QLD australia
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that a lot of things going on there and not blowing any fuses

have seen this in a hyundai

unplug the foot brake switch see if anything improves

then try the units thread adjustment

if no better replace the foot brake switch

post back
 

Last edited by dirty hands; 01-20-2016 at 11:35 PM.
  #3  
Old 01-28-2016, 07:31 PM
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Originally Posted by dirty hands View Post
that a lot of things going on there and not blowing any fuses

have seen this in a hyundai

unplug the foot brake switch see if anything improves

then try the units thread adjustment

if no better replace the foot brake switch

post back
Dear DirtyHands,
I got your msg, but several things happened.
Friday morning, while driving to work I was able to reproduce the problem 20 times in a raw: Turning OFF and ON(max) the fan. Each time radio got off and on within a second or so. I was happy, because if the problem is permanent, you can trace it.
Friday evening, till to day: NO MORE PROBLEM. It disappeared.
Pressing brake, or turning fan make no more effects on the radio, headlight and clock.
I was prepared to change alternator, for experiment, but did not have to.
I am sorry, I could not detect, repair and report here the problem.
However, if it reappears, I shall write again.
 
  #4  
Old 01-29-2016, 01:32 AM
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happy the car is working
 
  #5  
Old 01-29-2016, 05:59 PM
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Sometimes one of the larger fuses can corrode resulting in poor connection.

Check voltage at one of the items that is dims or has a problem to determine if the volts are dropping. If so, start tracing back until the voltage becomes normal again.
 
  #6  
Old 01-30-2016, 09:24 PM
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Originally Posted by toyomoho View Post
Sometimes one of the larger fuses can corrode resulting in poor connection.

Check voltage at one of the items that is dims or has a problem to determine if the volts are dropping. If so, start tracing back until the voltage becomes normal again.
Thank you, Joey,
I was thinking smtg along main fuse-relay-computer.
However, the problem disappeared. A corroded fuse can not un-corrode.
And, this is FL car. Not a spec of rust, at 16 years.
 
  #7  
Old 01-31-2016, 05:45 PM
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There are two small noise filters capacitors in the fuse box behind the dash board.
 
  #8  
Old 04-12-2016, 02:21 PM
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Originally Posted by toyomoho View Post
There are two small noise filters capacitors in the fuse box behind the dash board.

Dear All Toyota Friends,
I think I found the answer. Problem disappeared 2 months ago.
One day I could not start the engine. Heard click and EVERYTHING went dark.
Dome light, clock, dashboard lights.
Inspected electrical parts/connections, starting from battery.
Tried to twist-wiggle the battery terminals, they appeared solid.
Then started testing with a light bulb and wire.
(did not have multimeter with me)
When touching the battery lead terminal there is light.
When touching the 6-mm bolt on the lead clamp, there was no light.
I tightened this bolt (10-mm wrench), click, all lights came back on.

I am still puzzled by what happened, because, with a loose el. connection, the car started perfectly well when BIG current was drawn, and only when small changes on current were needed, the problem exhibited.

With one gentle tightening of the clamp bolt all problems disappeared.

Thank you again with all your ideas, hope my experience will be helpful.

Best,

Nick
 
  #9  
Old 04-12-2016, 07:53 PM
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Great job in running down the problem!

Thanks for posting with your find.
 
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