Rear Amber Turn Signals in '86 Cutlass

[popeye1978]

In March there was a discussion here that Cutlass Supremes built for export in the late '70s had rear amber turn signals, as a "see if I can" project -- and as I couldn't find a thread here on that topic -- I started looking-into what would have to be done to add them to my '86 ... and success! Here's an "after" video I finished last night, I still have to edit/post a "before" video -- so non-car-people family & friends can understand the issue -- and finish a write-up for it.

 

[565bbchevy]

I always thought brake lights have to be red to be legal here.

 

[pontiacgp]

 

[fleming442]

That's pretty cool!
I'm guessing they're white bulbs behind the red lens. Try reds.

 

[popeye1978]

I always thought brake lights have to be red to be legal here.

Well, it's passed inspection every year for the last 5 years -- including an Enhanced Inspection after the fire -- and this is the first time anyone has said anything about it, but now that you've pointed-it-out I see what you mean. Thank you

 

[popeye1978]

That's pretty cool!
I'm guessing they're white bulbs behind the red lens. Try reds.

Thank you!

 

[KCP]

How did you seperate the brake and turn signals coming from the brake switch?

 

[565bbchevy]

What if you modified the remaining portion of the reverse light lens to house your amber turn signals so they are more visible.

 

[pontiacgp]

they only used amber with separated turn signal lenses. Brakes lights are red everywhere.

 

[popeye1978]

I write software test procedures for a living so I was most comfortable writing the "how to" as a technical paper ... if you'd like all of this in PDF form -- so you can print it or just ease-of-use -- then send me a PM

Due to character-count restrictions, below is Part 1


INTRODUCTION
STOCK REAR LIGHTING
Rear of ’86 Cutlass Supreme 2-Door has been designed with three types of lights:

1. License Plate Lights: white, controlled by the headlamp switch
2. Reverse Lights: white, controlled by gearshift position (lights ON if gearshift is in “Reverse”)
3. Taillights: red dual-filament bulbs (1157)

Filament 1 acts as a marker light and is controlled by the headlamp switch​

Filament 2 operates as both turn signal (flashing) and stop lamp (solid), TURN SIGNAL takes precedence over STOP;
EXAMPLE: if braking and signaling left, the Left Taillight will flash while Right Taillight will be solid​

GOALS

1. Add amber turn signals to rear of the car (Rear Amber Lights)
2. Make appropriate modification(s) so in each Taillight Filament 2 operates only as a stop lamp
3. If necessary, restoration to Stock [Lighting] Configuration requires minimal effort

PROJECT AREAS
There are three “areas” of the project:

1. Choosing Amber Lights
2. Turn Signal Switch (TSS)
3. Rear Turn Wiring

CHOICE OF AMBER LIGHTS

I chose to use Switchback LED strips that are wired to use only the yellow LEDs (the white LEDs are not connected to a power source) and then affixed them to the top of the Reverse Lights.

Note​ An idea I was pursuing was to wire the Reverse Lights with switchback LED bulbs; this would have required changing the original 1156 (single-filament) Right-Angle Reverse Light sockets to 1157 (double-filament) Right-Angle sockets and wiring the sockets so: White filament of both Switchback LEDs lights-up when car shifted into “Reverse” Yellow filament of appropriate Switchback LED lights-up as a turn signal I rejected this idea when during a night-time test I noticed that the Reverse Lights didn’t seem to be evenly illuminated across the ‘strip’ of the light housing as the bulbs are not centered in the strip but are about 1/3 of the way from the license plate … I felt the concentration of yellow light from a turn signal would be too close to the centerline of the car and thus may not be a good indicator of the “direction of turn” _____ I also considered somehow modifying the Reverse Light housings – as in taking them apart to do some sort of modification – but I rejected that idea as if I ever again needed to replace the Reverse Lights I would have to repeat the modification and, well, I don’t want to be breaking any during my “experiments”

TURN SIGNAL SWITCH

DISCUSSION
Figure 3.1-1 has the electrical schematic of the Turn Signal Switch (TSS) for the 2-door Cutlass Supreme, taken from the “1986 Oldsmobile Cutlass Supreme / Custom Cruiser Service Manual;” note:

• TSS has an input from the Brake Switch (white wire)
• TSS has inputs from the Turn Signal Flasher and Hazard Flasher, position of their respective switches determines which lights flash … to include that for the Rear Taillights, “Turn Flash” overrides “[Solid] Brake” overrides “Hazard Flash”
• There is only one output to the Left Taillight (yellow wire)
• There is only one output to the Right Taillight (green wire)

… therefore the solution will have to:

• For the Taillights, “override the overrides”
• Make the Rear Amber Lights work as appropriate

​

Figure 3.1-1. Cutlass Supreme (2-Dr) Exterior Lights


For ideas of how to solve the problem, I had a vague memory there were GM cars in the ‘80s designed with Rear Amber Lights and after some research focused on 1986 Oldsmobile Delta 88s; these vehicles have Rear Amber Lights and as they are the same-year model as my Cutlass Supreme:

• IF the TSSs were the difference – and thus maybe part of the solution – then it was very likely the Delta 88 TSS would physically fit in my Cutlass Supreme
• High chance that documents & diagrams to be analyzed would be written/depicted in the same editorial style as manuals I already own
• If I would have had to buy additional books (which I did end-up doing) the additions would round-out / look better next to the ’86 manuals I already own

Figure 3.1-2 shows the TSS for the C/H cars, taken from the “1986 Oldsmobile Electrical Troubleshooting Supplement;” note:

• The TSS has the same “overrides” circuitry
• For Delta 88s, the Brake Switch does not connect to the TSS – it goes straight back to the taillights – therefore the overrides are not used in Delta 88s

… and referring to parts catalogs confirmed the ’86 Cutlass Supremes used the same model TSS as the ’86 Delta 88s.

​

Figure 3.1-2. C and H Turn/Hazard/Stop Lights


_____

The conceptual solution:

1. Run two new wires – Left Rear Amber & Right Rear Amber – between the TSS and the (new) Rear Amber Lights
2. Connect/splice these wires directly, without passing-through the TSS:
   • Brake Switch Output (white wire)
   • Left Taillight (yellow wire)
   • Right Taillight (green wire)
3. Connect the (new) Left Rear Amber & Right Rear Amber wires to the TSS

IMPLEMENTATION

Preparation

1. Buy:
   • A set of TSS connectors, including wire terminals
   • 1 brand-new TSS
2. Convert the new TSS into an Adapter Harness; on the new TSS:
   1. Cut off the assembly that is connected to the steering wheel / turn signal lever
   2. At the “steering wheel end” of the wires:
      • Splice together the white, yellow, and green wires
      • Mount a terminal at the end of each of the other wires and arrange them in a female TSS connector in same slots/order as on TSS; think of this as
        Connector New Female 2 (NF2) while the other end is Connector New Male 2 (NM2)

In the car

1. Ensure the new Left Rear Amber and Right Rear Amber wires have been run
2. Mount a terminal at the TSS end of each of the (new) Left Rear Amber & Right Rear Amber wires
3. Separate the Body Harness/TSS connection, connector designators are:
   1. Body Harness: Existing Female 1 (EF1)
   2. TSS: Existing Male 1 (EM1)
4. On NF2, insert the Left Rear Amber & Right Rear Amber terminals into the appropriate “Left Rear” & “Right Rear” slots
5. Connect EM1 to NF2
6. Connect EF1 to NM2

NOTE​ Adapter Harness is the second/revised idea; original idea was to physically swap terminals in EF1 & use new TSS connectors to make the splice but test fitting found there was not enough slack in the wires to safely remove terminals from the connector

​

Figure 3.2-1. As-Bought TSS

Figure 3.2-2. Prep of Step 2.2

Figure 3.2-3. Splice Made & Terminals Mounted

Figure 3.2-4. Adapter Harness

Figure 3.2-5. Electrical Schematic