posted August 2019

1st Gen 4Runner (84-89) LED Lighting

This article explains everything I know about the lighting in my 1985 4Runner and the modifications I've made to my systems.

Bulb Types and LED Equivalents

The following table shows the bulb types and LED equivalents. I purchased all of my LED lighting (with the exception of my dome light replacement) from Super Bright LEDs and I'm extremely happy with their build quality and shipping times. The dome light replacement was purchased from Low Range Off Road.

Front SML 194 AMB 194-AHP5
Front TSL 1073 AMB 1156-A27-T
Backup 1073 WHT 1156-NW27-T
Stop and Tail 1034 RED 1156-R27-T
License 89 WHT 67-CW12-G
Rear SML 194 RED 194-RHP5
Rear TSL 1073 AMB 1156-A27-T
Interior Dome 12V-3CP WHT 3022-NW4*
Luggage 12V-3CP WHT 3022-NW4
Map BA9S WHT BA9S-CWHP5
Door Courtesy 12V-3CP WHT 3022-NW4
Glove 74 WHT 74-NWHP
Inclinometer (2x) 194 GRN 194-GHP5
Instrument Backlight (3x) 194 GRN 194-GHP5
Heater Controls 74 GRN 74-GHP3
Instrument Turn (2x) 194 GRN 194-GHP5
Inst Bright Indicator 194 BLU 194-BHP5
Inst Check Engine 74 AMB 74-AHP3
Inst 4WD 74 GRN 74-GHP3
Inst Fasten Seatbelt 74 RED 74-RHP3
Inst Charge 194 RED 194-RHP5
Inst Brake 194 RED 194-RHP5
Inst BackDoor 74 RED 74-RHP3
Defrost switch Thick base GRN NEO 4mm
Deck lamp ON switch Thick base AMB NEO 4mm

A note on LED colors

When you swap in LEDs for incandescent bulbs, you should use the same color LED as the lense the light will shine through. A white LED shining through a red lense will appear pink and washed out. For the interior back lighting, some of the "lenses" are clear and the incandesent bulb has a green cover over it, you can change the backlight color by simply using a different color of bulb. If the lense that is being shone through is tinted (e.g. rear window switch or check engine light) then you cannot change the color without removing the tint (this would not be recommended for the instrument cluster, but can be done on some switches).

A note on dimming of LEDs

The first generation 4Runner came with a 2 wire rheostat to affect the brightness of the instrument backlighting. When you use LEDs, the effectiveness of the 2 wire rheostat is remarkably dimished and is almost imperceptable. The backlights will appear to be either on or off. You can swap in a 3 wire rheostat from a later model Toyota to get back some of the dimmability, but it still won't get as dim as an incandescent bulb.

Modifications and Issues

Change Backlight Colors

This is a fairly simple modification if you're already digging in to your dash to swap in LEDs. I changed my backlighting to amber and I'm extremely happy with it.

To change the backlight color you must change the 3 194 bulbs in the cluster, 2 194 bulbs in the inclinometer (if equipped), 1 74 bulb in heater controls, and 1 NEO bulb in the rear window defroster. Note that the rear window up/down switch has a tinted panel, so changing this color means modification of the switch.

3 Wire Rheostat Upgrade

Go to a pick and pull and find a 3 wire rheostat from any mid-90s Toyota (I snagged mine out of a RAV4). Take the rheostat and the 3 wire plug. One of the wires on the 3 wire rheostat needs a constant 12v+ when the vehicle's lights are on, power from the tail lights is suitable for this. The other two wires match to the existing wires on the rheostat. Your colors may be different from mine, pin 1(top) was green, 2/3 were side by side and were white/black and white/green. On the 2 wire rheostat, both wires were the same color. Hook up the 2 existing wires to the bottom pins of the 3 wire plug (2/3), and hook 12v+ up to the top pin.

Pin 1 (12V+) is on top, pin 2/3 are on the bottom.

In this video, you can get an idea of the level of dimming possible. It's not perfect, but it's significantly better than the 2 wire dimmer. The video doesn't really do it justice, it looks better in person... but watch the reflection of the lights on the other surfaces to get an idea.

Dimming with LED and 3 wire rheostat

Fast Flash Turn Signals

If you swap your turn signals for LED bulbs, the resistance is so low on the LED bulb that the flasher thinks you've got a burnt out bulb. The flasher has a built in safety mechanism to detect this condition and fast flashes your signals. You can correct this in a multitude of ways:

  • Purchase resistors for LED bulb and wire them in parallel to the bulb to simulate the resistance of an incandescant bulb.
  • Purchase a new flasher that is compatible with LED bulbs (I am not aware of one that works for the 1st Gen 4Runner)
  • Modify the existing flasher, by snipping the resistor on the fault detection circuitry. This modification, while irreversible, is also free!

I chose to snip the resistor on my existing flasher. Remove the flasher from the driver's side kick panel, take the circuit board out of the housing, and snip the appropriate resistor. Note that I did not take the picture below and I do not claim credit for it.

Eliminate quick flash by snipping the appropriate resistor.

Lights are on when they aren't supposed to be

This is a fairly common problem with adding LEDs to our trucks. The issue occurs because our trucks are "switched ground". This means that each LED has a constant 12V+ being applied to it even when it's not switched on. Note that the 12V+ being applied isn't necessarily always on, it may be controlled by IGN or the tail light relay. In the case of the dome and courtesy lights however, they are always on 12v+. If you have a "leaky ground", then the bulb may get a partially completed circuit and "glow" just a bit when it's not supposed to be on. To remedy this condition you must find and fix the leaky ground which is typically at the switch that the controls the light.

I had this problem with my dome and courtesy lights, as well as my stop, turn, tail lights not working properly when the brakes were pressed (both turn signals in the cluster lit up) or when the turn signals were used (the brake lights and tail lights would turn on with the turn signals).

The issue with the dome and courtesy lights was simply due to the door switches. I removed them, cleaned them up and re-installed, and it's worked perfectly ever since.

The issue with the stop/turn/tail lights was due to the trailer wiring harness that was installed by the previous owner. Since I didn't plan on needing that anytime soon, I simply removed it. We'll see what happens if I have to install another one.