1965-68 Sequential Turn Signal Circuit

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Operation & Diagrams

The basic parts of the sequential system are:
• Turn Signal Switch (located in the Steering Column)
• Turn Signal Indicator Relay (mounted to the Steering Column Support)
• Turn Signal Relay (located under the Package Tray, in the Trunk)
• Flasher or Sequencer Unit (mounted with the Turn Signal Relay)
• Stop Light Relay (also mounted with the Sequencer and Turn Signal Relay)

The stop light circuit is wired into the turn signal circuit. The flasher assembly consists of a motor, three staggered cams on a shaft and three sets of contacts.  Each set of contacts is connected to one of the three rear light bulbs through the Turn Signal Relay.

When the Turn Signal Lever is actuated, a circuit is completed to the Turn Signal Relay and to the respective right or left side solenoid in that relay.  A set of four contact points is actuated by each solenoid to connect the respective rear lights to the flasher and motor circuit.  (Three contacts connect the three rear lights and one contact connects the front turn signal light.)

The following wires are connected together at the Turn Signal Switch when lifted to the right hand position: (694, 362) and (8, 441, 458).  In the left-hand position, wires (694, 363) and (8, 440, 458) are connected.

When the Turn signal Switch is actuated, either right or left, the circuit energizes the Flasher Motor which turns the flasher cam.  As the cams rotate, the three sets of contacts are closed in sequence and the three rear stop lights are illuminated in sequence beginning at the inboard light, then the center light and then the outboard light.  All three lights go out at the same time and the cycle is repeated as long as the turn signal switch is closed. The front parking light bulb flashes at the same time as the center rear bulb.  When the Turn signal Switch is canceled, all the light bulbs go out immediately.

The brake light circuit in this sequential system is connected differently than in the standard turn signal circuit.  In the standard circuit, the brake lights are connected through the turn signal switch.  In the sequential system, the brake lights are connected to the turn signal circuit at the Turn signal Relay.  When the Turn Signal Lever is in the neutral position, no electrical connection is made at the Turn Signal Switch and the Turn Signal Relay solenoids are at the rest position.  Six normally closed contacts in the Turn Signal Relay are connected and complete the circuit from the Brake Light Switch, through the Stop Light Relay* to the stop lights.

TROUBLESHOOTING TESTS (assuming all chassis grounds are solid to the battery Neg):

First, eliminate the possibility of any problems which can be found by a visual inspection and the possibility of a burned out bulb.  The only possible part left to check is the Turn Signal Relay in the taped package.

If the bulb and socket and wiring has continuity to the Turn Signal Relay and all of the lights but one operate, then make a test for power at the relay terminal of the bulb in question. If no power is available, the Turn Signal Relay contact is defective. This test is made with the ignition switch ON and the Turn Signal Switch in the proper position, up or down.

This problem can be isolated to the turn signal switch, the turn signal relay or the wiring from the switch to the relay.

Test for power at the Turn Signal Switch disconnect-terminals with the Turn Signal Lever in the center 'non-functioning' position and the ignition Key Switch turned ON.  If there is no power at the terminals leading to the motor, Turn Signal Indicator Relay, or the Turn Signal Relay, the Turn Signal Switch is defective.  If power is available to all these terminals, the trouble can be isolated to the wire leading to the Turn Signal Relay coil or to the relay unit.  Test for power at the turn signal relay disconnect at the terminal leading from the switch.  If power is not available, the wiring is open between the switch and the relay.  If power is present, the turn signal relay is defective.  This wire energizes the relay coil, which switches the circuit from the stop light wires to the turn signal wires.

* The Stop Light Relay was only used in early production models.

If one set of brake lights does not operate and the turn signals do operate, the problem must be a defective Turn Signal Relay.

If all stop lights do not operate, the problem can be at the stop light switch, Stop Light Relay, Turn Signal Relay or the wires between the three components may be open.

Test for power across the Stop Light Switch terminals with the Brake Pedal depressed.  If there is no power, the Stop Light Switch is defective.  If there is power, test for power at the Stop Light Relay to determine if it has a good ground connection and if it is operating.  If there is no power, there is a defect in the wiring between the Stop Light Switch and the Stop Light Relay.  If there is power and the relay is functional, check the wire and connections between the Stop Light Relay and the Turn Signal Relay.  If the wire is good, there is a defective connection inside the Turn Signal Relay.


This problem will require visual, audible, and power tests at all of the sequential turn signal components.  Since the stop lights operate, we can temporarily eliminate the Turn Signal Relay as the trouble spot.  Using the circuit diagrams as reference, test for power at the Turn Signal Switch first in both left and right positions to determine if power is available from it to the Turn Signal Indicator Relay, the Flasher and Motor Unit and the Turn Signal relay.  All tests are made with ignition Kew Switch and Turn Signal Switch, ON.  After eliminating the Turn Signal Switch as the fault, check power at the Turn Signal Indicator Relay to determine if it is operating properly.  Next, go to the Flasher and Motor Unit and test all of its leads for power.  The last possible unit is the Turn Signal Relay.

Test the components in this order:
1. Turn Signal Switch
2. Turn Signal Indicator Relay
3. Flasher and Motor Unit
4. Turn Signal Relay

Test the power source and then the power output before assuming the component is defective.  The fault may be in the wiring between components.

The emergency warning flasher circuit utilizes the sequential flasher and motor unit as the flashing element instead of a heavy-duty flasher can.  In addition, the system requires two double-pole relays versus three relays in the older system.

The flasher and motor unit schematic shows one set of contacts and one operating coil has been eliminated. This set of contacts was used as the parking switch for the sequential motor, the motor will now park in any position.

The switch for the emergency warning flasher circuit has been relocated to the right-hand side of the steering column, opposite the turn signal switch lever.  Both switches are in a one-unit assembly.

The turn signal circuit can only be operated when the ignition switch is in the ACC position or the ON position.  The emergency warning flasher circuit receives power directly from the battery through a separate circuit breaker and can be operated independently of any other circuit.

Illustration 17001.3-12 shows the emergency warning flasher circuit.  The switch is shown in the OFF position and the relays in the de-energized position.

When the switch is pushed in, or in the ON position, several circuits are completed:
1. Wire #441 completes the circuit to the right-hand solenoid in the turn signal relay.  This connects the right-hand front and rear lights to the flasher motor circuit.

2. Wire #440 completes the circuit to the left-hand solenoid in the turn signal relay.  This connects the left-hand front and rear lights to the flasher motor circuit.

3. With the ignition switch on, wire #514 de-energizes relay coils A and B through normally closed contacts.

4. Wire #458 completes the circuit through the coil and contact points of the turn signal indicator relay.  Wire #459 completes the circuit which runs the Flasher Motor.

5. Wire #694 completes the circuit through the contact points of relay A and on through wires 362 and 363 to the right- and left-hand indicator bulbs.

6. Since the contact points of relay B are closed, wires 4364, 437A, and 438A are in effect a single wire circuit. This combines the three sequential signals, coming from the flasher, into a single flashing signal.

The flashing signal is then sent through the closed points of the Turn Signal Relay to all six rear lights and two front lights. The two Indicator Lights on the dash panel go out each time the current draw from the eight exterior lights causes the Turn Signal Indicator Relay contact points to open. The dashboard Indicator Lights flash at the same speed as the exterior lights, but at opposite times.

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