Lakota
Rides a rusted horse
How Do My Turn Signals Work.
**************HOW DO MY TURN SIGNALS WORK? *****************
Turn-signals are one of the most misunderstood sub systems in most Vehicles today. They really are simple when you stop and think about HOW the system performs its job, and why it is wired the way it is. Most commonly, the system is miss-wired and interacts with the brake lamp system causing non functioning turn-signals under braking Conditions. And 4 way flashing action when not in braking mode. Hopefully we can walk you through the "Pitfalls" of Turn-signals and make it a bit easier to install and troubleshoot...
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OVERVIEW:
The Turn-signal system is a System that is isolated from other lamp circuits, but appears to function with the Brake lamp system, which, in part is true...
The Turn signal on a traditional system is a shared element with the brake lamp function at the bulb to the rear of the vehicle. The most common misconception is "I can wire my Turn-signals and brake lamps together at the light housing and it will be fine...and that's where the trouble begins. As you read on, hopefully you will see how this system functions and how the isolation is important to make it function properly.
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POWER FEED AND FLASH UNIT:
Power on a traditional flash unit is delivered to the system VIA the Flash unit. A FUSED, SWITCHED lead is run from the Fuse buss to the flasher, so that it only receives power in the "Hot in Run" position.
FROM the Flasher, a wire is run To the Center wiper (or Movable contact) of the Turn signal switch inside the steering column.
The flasher operates from internal heat on a tungsten bi~metallic"strip" that makes or breaks the contact at the switch side of the contact, Or power output side.
As the system Lamp load is imposed on the flasher unit, the bimetallic strip heats up, and curls up... breaking contact to the switch... It then cools down very rapidly, and makes contact again, the lamp load again heats the strip and it opens up. THUS: "Flash"
When the load is under matched to the Flash unit (Bulb(s) burned out), the flash cycle is slowed or stuck "On”. This is what we perceive as a lamp outage and when this occurs. We pull over and have a new bulb put in...
The reason this occurs. Is because the Lamp load on the bimetallic Strip inside the flasher unit has been reduced to a point where the time allotted for heat is extended (Slowing the flash rate) OR never reaches the heat point of the strip (turning on and staying on)..
When these flash units fail. Usually the load on the strip has exceeded it's capability to recover and the strip just melts, Leaving the switch contact side "Open” from power... This is when we normally put a new flasher in. Causes of this type of failure can range from Age of the flash unit, to overtaxing of the lamp load... (As in Trailer lamps) Or a short within the electrical system.
The other side of the Coin is too many bulbs within the lamp load circuit. Taxing the Flasher unit. This causes the bimetallic tungsten strip to heat and cool at a Very rapid rate...
The more current draw THROUGH the flasher unit the faster it opens and closes the contact...
The Root causes of this type of failure are when you EXCEED the lamp count, Exceed the recommended WATTAGE of the bulbs, Install the WRONG bulb in the system (I.E. a single element bulb, where a duel should live), Shorting of the lamp system (common Culprit, Trailer plugs), And the addition of EXTRA lamps (such as a trailer) in the circuit without upgrading the flash unit.
ALWAYS install the recommended WATTAGE or Bulb Number when replacing the bulbs or this malady can occur...
The net result usually is a very rapid flash rate. And in some cases, failure of the flasher unit...Or premature failures on subsequent units...
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THE TURN~SIGNALS SWITCH:
This little switch has been responsible for more "Hair pulling” Incidents than most other parts of the Vehicle... When you understand HOW it works, and WHY it works the way it does. It’s really quite simple.
At the bottom of the steering column on traditional Turn signal systems, there is a Plug. From that plug all the system signals (power) goes in and comes out. And an added system, a wire from the brake lamp switch.
At this plug you will find Flash unit power in to the switch Handel, TWO sets of wires for the Left and right Turn signal lamp socket power, Those will be front left, rear left, front right, and rear right. These wires bring power to the lamps for turn signal AND brake lamps to the rear. Also at that plug you will find a wire for the brake lamp system from the Brake lamp switch.
The switch itself, Located below the horn ring on most traditional Systems, is like any other, except...It is two switches in one, the Left side and Right side. It also provides the isolation required between the Brake lamp system and the turn signal system.
To understand how the switch works, we can view one side of it for an example. If you remove the Steering wheel, and usually the horn assembly you can see the turn signal switches, usually on a plastic base plate, driven by a "plastic Cam" set off by two "spring steel" contacts that shift contact points when the base plate is activated with turn signal arm.
Let's look at the left side only for now...
As you activate the left turn signal, the following takes place. The cam rotates and the spring steel contact "Flexes" removing contact from the normally closed contact to the normally open contact.
This switch is wired traditionally as such:
· The Center wiper (movable contact or cam contact) is Lamp output.
· The Normally Closed Contact , Is Brake lamp power From The Brake lamp switch.
· The Normally open Contact is Power from the flash unit.
When No activation is present at the turn signal, the brake lamps are configured to light when the pedal is depressed through the Normally closed contact of the switch and the Center wiper (lamp output).
Now , assuming you are at a stop light, turning left, The contact switches power when activated by the cam assembly, and opens (or turns OFF) the left brake lamp from the normally CLOSED contact And It now has contact Between the center wiper (lamp output) and the normally OPEN contact (the Flash unit).
Were the brake lamp and the Turn signal to both be on together, The result would be you would never see the Flashing of the signal. Since the same filament is shared by both systems, Even though both would be operable, when the flash unit was off, the brake power would still be on, making no noticeable change in the bulb.
If it were wired this way and both brake lamps were common to each other on the power leg. AND no brake pedal was pushed (brake power off) BOTH rear lamps would flash together.
In the above PROPER configuration, both systems would Gain Isolation from each other through the switch...
The EXACT same wiring is true for the right side, with the exception of the brake lamp power is picked up from the Left contact (daisy chained).
------------------------------------------------------
FUNCTIONALITY:
Let's Review. The system works in the following manner.
When NO turn signal is selected, BOTH brake lamps will receive power when the pedal is pushed...
When the Left Turn signal is selected, The Brake lamp for the left side is disabled by the turn signal switch and the bulb now receives power from the flash unit. At the same time NO change has been made to the right side Brake lamp. The Result:
Left lamp flashing, Right lamp steady with brakes on. Right lamp is out when brakes are off.
Now, Switch to the right side. The reverse becomes true...
The right side Brake lamp is disabled, and power to the lamp is now provided by the flash unit. Brakes on or off...
The left side remains on (no Change to the left side) steady with brake power, and out without it.
This is how the two systems are Isolated...and the most problematic for a Novice to understand, primarily because nobody ever took the time to explain it to them in any detail.
------------------------------------------------------
**************HOW DO MY TURN SIGNALS WORK? *****************
Turn-signals are one of the most misunderstood sub systems in most Vehicles today. They really are simple when you stop and think about HOW the system performs its job, and why it is wired the way it is. Most commonly, the system is miss-wired and interacts with the brake lamp system causing non functioning turn-signals under braking Conditions. And 4 way flashing action when not in braking mode. Hopefully we can walk you through the "Pitfalls" of Turn-signals and make it a bit easier to install and troubleshoot...
-------------------------------------------------------
OVERVIEW:
The Turn-signal system is a System that is isolated from other lamp circuits, but appears to function with the Brake lamp system, which, in part is true...
The Turn signal on a traditional system is a shared element with the brake lamp function at the bulb to the rear of the vehicle. The most common misconception is "I can wire my Turn-signals and brake lamps together at the light housing and it will be fine...and that's where the trouble begins. As you read on, hopefully you will see how this system functions and how the isolation is important to make it function properly.
-------------------------------------------------------
POWER FEED AND FLASH UNIT:
Power on a traditional flash unit is delivered to the system VIA the Flash unit. A FUSED, SWITCHED lead is run from the Fuse buss to the flasher, so that it only receives power in the "Hot in Run" position.
FROM the Flasher, a wire is run To the Center wiper (or Movable contact) of the Turn signal switch inside the steering column.
The flasher operates from internal heat on a tungsten bi~metallic"strip" that makes or breaks the contact at the switch side of the contact, Or power output side.
As the system Lamp load is imposed on the flasher unit, the bimetallic strip heats up, and curls up... breaking contact to the switch... It then cools down very rapidly, and makes contact again, the lamp load again heats the strip and it opens up. THUS: "Flash"
When the load is under matched to the Flash unit (Bulb(s) burned out), the flash cycle is slowed or stuck "On”. This is what we perceive as a lamp outage and when this occurs. We pull over and have a new bulb put in...
The reason this occurs. Is because the Lamp load on the bimetallic Strip inside the flasher unit has been reduced to a point where the time allotted for heat is extended (Slowing the flash rate) OR never reaches the heat point of the strip (turning on and staying on)..
When these flash units fail. Usually the load on the strip has exceeded it's capability to recover and the strip just melts, Leaving the switch contact side "Open” from power... This is when we normally put a new flasher in. Causes of this type of failure can range from Age of the flash unit, to overtaxing of the lamp load... (As in Trailer lamps) Or a short within the electrical system.
The other side of the Coin is too many bulbs within the lamp load circuit. Taxing the Flasher unit. This causes the bimetallic tungsten strip to heat and cool at a Very rapid rate...
The more current draw THROUGH the flasher unit the faster it opens and closes the contact...
The Root causes of this type of failure are when you EXCEED the lamp count, Exceed the recommended WATTAGE of the bulbs, Install the WRONG bulb in the system (I.E. a single element bulb, where a duel should live), Shorting of the lamp system (common Culprit, Trailer plugs), And the addition of EXTRA lamps (such as a trailer) in the circuit without upgrading the flash unit.
ALWAYS install the recommended WATTAGE or Bulb Number when replacing the bulbs or this malady can occur...
The net result usually is a very rapid flash rate. And in some cases, failure of the flasher unit...Or premature failures on subsequent units...
------------------------------------------------------
THE TURN~SIGNALS SWITCH:
This little switch has been responsible for more "Hair pulling” Incidents than most other parts of the Vehicle... When you understand HOW it works, and WHY it works the way it does. It’s really quite simple.
At the bottom of the steering column on traditional Turn signal systems, there is a Plug. From that plug all the system signals (power) goes in and comes out. And an added system, a wire from the brake lamp switch.
At this plug you will find Flash unit power in to the switch Handel, TWO sets of wires for the Left and right Turn signal lamp socket power, Those will be front left, rear left, front right, and rear right. These wires bring power to the lamps for turn signal AND brake lamps to the rear. Also at that plug you will find a wire for the brake lamp system from the Brake lamp switch.
The switch itself, Located below the horn ring on most traditional Systems, is like any other, except...It is two switches in one, the Left side and Right side. It also provides the isolation required between the Brake lamp system and the turn signal system.
To understand how the switch works, we can view one side of it for an example. If you remove the Steering wheel, and usually the horn assembly you can see the turn signal switches, usually on a plastic base plate, driven by a "plastic Cam" set off by two "spring steel" contacts that shift contact points when the base plate is activated with turn signal arm.
Let's look at the left side only for now...
As you activate the left turn signal, the following takes place. The cam rotates and the spring steel contact "Flexes" removing contact from the normally closed contact to the normally open contact.
This switch is wired traditionally as such:
· The Center wiper (movable contact or cam contact) is Lamp output.
· The Normally Closed Contact , Is Brake lamp power From The Brake lamp switch.
· The Normally open Contact is Power from the flash unit.
When No activation is present at the turn signal, the brake lamps are configured to light when the pedal is depressed through the Normally closed contact of the switch and the Center wiper (lamp output).
Now , assuming you are at a stop light, turning left, The contact switches power when activated by the cam assembly, and opens (or turns OFF) the left brake lamp from the normally CLOSED contact And It now has contact Between the center wiper (lamp output) and the normally OPEN contact (the Flash unit).
Were the brake lamp and the Turn signal to both be on together, The result would be you would never see the Flashing of the signal. Since the same filament is shared by both systems, Even though both would be operable, when the flash unit was off, the brake power would still be on, making no noticeable change in the bulb.
If it were wired this way and both brake lamps were common to each other on the power leg. AND no brake pedal was pushed (brake power off) BOTH rear lamps would flash together.
In the above PROPER configuration, both systems would Gain Isolation from each other through the switch...
The EXACT same wiring is true for the right side, with the exception of the brake lamp power is picked up from the Left contact (daisy chained).
------------------------------------------------------
FUNCTIONALITY:
Let's Review. The system works in the following manner.
When NO turn signal is selected, BOTH brake lamps will receive power when the pedal is pushed...
When the Left Turn signal is selected, The Brake lamp for the left side is disabled by the turn signal switch and the bulb now receives power from the flash unit. At the same time NO change has been made to the right side Brake lamp. The Result:
Left lamp flashing, Right lamp steady with brakes on. Right lamp is out when brakes are off.
Now, Switch to the right side. The reverse becomes true...
The right side Brake lamp is disabled, and power to the lamp is now provided by the flash unit. Brakes on or off...
The left side remains on (no Change to the left side) steady with brake power, and out without it.
This is how the two systems are Isolated...and the most problematic for a Novice to understand, primarily because nobody ever took the time to explain it to them in any detail.
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