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How to diagram your turn signal harness (Dietz 16-35)

Ernie Harris

New Member
Joined
Jul 27, 2025
1957 Jeep CJ-5
Dietz 16-35 Turn Signal Switch Identification and Wiring
Purpose
The wire colors on all Dietz 16-35 turn signals switches are not consistent through time as they used different suppliers. Rather than relying on wire colors, the switch can be identified by electrically mapping its internal contacts with a multimeter. This procedure can be repeated on any similar switch.
Identification Procedure

  1. Disconnect the turn signal switch completely from the vehicle.
    • Disconnect the flasher.
    • Disconnect the brake switch.
    • Disconnect all lamp wiring.
    • Ignore the two gray wires, as they are the indicator lamp inside the switch and are not part of the switching contacts.
(not all the switches I’ve seen have the lamp in the switch)
  1. Number the six remaining wires.
Wire Number
Wire Color
1White
2Black
3Brown
4Green
5Blue
6Yellow
  1. Using a multimeter in continuity mode, identify which wires are electrically connected in each of the three lever positions (Center, Left and Right).
Dietz 16-35 Continuity Test Sheet
CENTER Position
Mark each box with:

  • = Continuity
  • X = No Continuity
2
3
4
5
6
1
2
3
4
5

LEFT Position
2
3
4
5
6
1
2
3
4
5

RIGHT Position
2
3
4
5
6
1
2
3
4
5

Notes
  • Disconnect the switch completely from the vehicle before testing.
  • Disconnect the flasher and brake switch.
  • Ignore the two gray indicator lamp wires.
  • Test each pair only once.
  • Record for continuity and X for no continuity.
This format has two advantages:
  • You never accidentally test the same pair twice (1-2 and 2-1).
  • You can immediately compare the three switch positions and see exactly which contacts change. It’s a format I’ve used many times for reverse-engineering switches and relays.

  1. Use the continuity map to determine the function of each wire rather than relying on published color codes.
Understanding Continuity Testing on a Turn Signal Switch
What is Continuity?
Continuity simply means there is an electrical path between two wires.
When a multimeter is placed in continuity mode:

  • Meter Beeps = Those two wires are connected together inside the switch.
  • No Beep = Those two wires are isolated from one another.
The continuity test does not identify which wire is power, ground, front, or rear. It only tells you which wires become connected as the lever moves.

Why Test Three Positions?
A turn signal switch has three operating positions:

  • Center (Neutral)
  • Left Turn
  • Right Turn
The internal contacts change in each position.
By comparing which wires connect in each position, the function of every wire can be determined.


Center Position
The turn signals are OFF.
The only function the switch is performing is allowing the brake lights to work normally.
If two wires are connected only in the Center position, they are almost always part of the brake light circuit.
In my switch:
White (#1) ↔ Brown (#3)
This tells us that these two wires are connected whenever the turn signal is not being used.


Left Turn Position
When the lever is moved left, the switch disconnects the left rear brake light from the brake circuit and instead connects it to the flasher.
Any group of wires connected together in the Left position belong to the left turn signal circuit.
In my switch:
Black (#2)
Brown (#3)
Yellow (#6)

were all connected together.
That tells us:

  • One wire is the flasher input.
  • One wire goes to the left rear lamp.
  • One wire goes to the left front lamp.
The switch is routing the flasher to both left lamps.

Right Turn Position
The opposite occurs.
The right rear brake light is disconnected from the brake circuit and connected to the flasher.
In my switch:
Black (#2)
Green (#4)
Blue (#5)

were connected together.
This tells us:

  • One wire is still the flasher input.
  • One wire goes to the right rear lamp.
  • One wire goes to the right front lamp.

Determining Which Wire Is Which
Continuity identifies groups of wires.
The actual function of each wire is determined by combining the continuity map with knowledge of how a turn signal system operates.
For example:
The wire that connects to both the Left group and the Right group must be the flasher input.
The wire that only appears in the Left group and goes to the front lamp becomes the Left Front output.
The wire that only appears in the Right group and goes to the front lamp becomes the Right Front output.
The remaining wires become the rear stop/turn outputs.



  1. Once the wire functions have been identified, wire the switch according to the table below.
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Final Verified Wiring

Dietz Switch Connections

Dietz Wire
Color
Connect To
#1WhiteHarness #20 (Brake Light Switch Output)
#2BlackFlasher “L” (Load) Terminal
#3BrownHarness #24 (Left Rear Stop/Turn)
#4GreenHarness #23 (Right Rear Stop/Turn)
#5BlueHarness #21 (Right Front Turn Signal)
#6YellowHarness #22 (Left Front Turn Signal)
GrayGrayFlasher “P” (Pilot) Terminal
GrayGrayChassis Ground
Flasher Connections
Flasher Terminal
Connect To
XSwitched 12V from Ignition Switch
LDietz Black Wire (#2)
POne Gray Wire from Dietz Switch
The remaining Gray wire connects to chassis ground.
Harness Connections (For a Kaiser Willys 1957 CJ5 Harness)

KW Harness Wire
Connect To
#20Dietz White (#1)
#21Dietz Blue (#5)
#22Dietz Yellow (#6)
#23Dietz Green (#4)
#24Dietz Brown (#3)
 
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