How works the '57-59 turn signal system on Imperial ?
If you look at a '57, '58 or '59 Imperial ther's something different from the other Mopar of the same year : ther's no turn signal lever on the steering column ! The turn signals are actuated with a switch at the bottom of the Torqueflite controls pushbuttons.
The switch is a "on - off - on" push affair on '57 cars (at the top : right turn - at the bottom : left turn - in the middle : canceling) and a much ergonomic toggle switch with a small canceling button on '58 and '59 cars.
As there's no contact plate on the steering shaft the Chrysler engeneers had to imagine a special "automatic canceling switch" on the steering tube. This part (1770 498) has a small plastic pin actuated by the movement of the steering tube. The pin is often broken and then you haven't automatic canceling.
The third item of the circuit is the relay box which is hidden at the top of the driver's kick panel near the circuit breakers of the seat and windows. This "black box" has a lot of wiring coming to it, 11 terminals !!
Of course ther's also a flasher behind the dash (at the top of the speedo housing ..) and indicator lamps on the dash panel.
As i said the Imperial system is different from the others because ther's no physical movements of parts to cancel the turning lights. No return springs, no breaker plate, etc.. But the system must perform the same connections to turn signal lights AND stop lights ! So the relays of the box are a bit sophisticated. To understand the functions i have opened one of my spare "black box". And if ther's a poor groud somewhere you 'll have erratic functions or "buzzing" sounds ..
Here is the schematic of the turn signal circuit (scaned on the '57 FSM). I've colored the wires according to their real colors.
1/ How works the turn signal lever ? (note that the pics are '58-59 switch but the electrical functions are the same on '57). Click on thumbnails to enlarge
2/ How works the automatic canceling switch on the steering column ?
the release position all the terminals are grounded. So the orange and
violet wires are together grounded. When you steer to the left or the right the
pin breaks the corresponding connection, i.e if you steer to the left it's
like an open circuit between the switch and the orange wire. But the violet wire
remains grounded !
3/ How works the control box ?
First here is a view of the inside of the box.
The pic is a bit surexposed and i've add the corresponding numbers seen on the
external side and on the schematic. The red numbers
are connected to terminals, the blue numbers have
no terminals on exterior side.
This schematic has been drawed from my simulation physical software CrocodilPhysic. With this soft i could test the system on the computer !!! I've made some video so you'll see how the system really works. The animations has been captured with Wink
1st schematic: stop lights
When you brake the parts, the stop light switch is actuated and closed the rear lights. The relays are not actuated.
2nd schematic : right turn
red line = + 12 V . Black line = 0 V (ground) .
Gold line = blinked 12 V (from flasher)
3rd shematic : canceling the turn with the manual cancel switch
When you push the cancel switch you actuate the left relay (the relay is grounded via the cancel switch and the terminal # 5). So the ground line through the L automatic cancel, the # 3 and #10 terminals is opened. The right relay coil has its circuit and in the same time ther's no ground on the #5 terminal so the left relay opens also (even if you rest on the cancel button). Depending condition you could have one blinking of the 4 lights in a fraction of second..
It's difficult to show all these facts on a whole drawing !! Below i draw the system at the point just after i push the cancel button and before the two relays go off.
4rd shematic : canceling with a left (re)turn of the steering wheel.
Before seing what happens, note that if you
steer to the right, you 'll open the "R" automatic cancel switch but, as its
circuit is already opened nothing happens nd the lights still blink !
5th schematic : right turn and braking.
See below. Only the left stop light brights steady.
(i'll add different failures after testing with my simulation soft)
1st failure (from Rex's Imperial) :
ground problem at automatic cancel switch or bad switch
Let's see what's happen :
If ther's a cut in the violet or orange wire (or the two) the relays aren't grounded after release of the toggle switch. So the lights don't blink after release. Note that if only one of the wire (violet or orange) is broken the corresponding side won't blink but if the two wires are broken or if ther's a malfunction in the steering switch you won't have any turn signal after release of the toggle. The only way to repair (if you don't have a spare switch) is to grounded the violet and orange wires. You'll not have automatic canceling but you'll have turn signals !!
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