2004 Prius Stoplight

Hard to picture an array of LEDs failing given their theoretically infinite life. I'd look for something else in that circuit, most likely a loose or corroded connection. The array itself can be tested with any cheap ohmmeter. It should present the classical diode's large front-to-back resistance ratio. Set the ohmmeter on a low scale. You should low a resistance with the probes one way, very high resistance with the probes reversed.

The wiring harness is located inside the hatch and accessible through a pull-off door just behind the tail lamp assembly. Were it me, my first step would be setting up the condition that normally lights the array and then wigging the harness, a variation of what we call "percussive maintenance."

The harness you see inside that hatch provides power and control to the taillight, the reverse light and the turning indicator; not the LED array. If anyone knows where the connection for the LED array really is, I'd appreciate your information. It currently appears it is buried somewhere behind the assembly, which must be removed to gain access to any LED harness.

I agree the whole array ceasing to function was a major surprise. That's why I am here looking for others with the same experience and, perhaps, knowledge of what was done to remedy the situation.

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The connection to the LED array is, as you write, most likely internal to the assembly. Only a single wire is necessary since the array would most likely used a shared ground connection. I find it highly unlikely they would run a harness from the dash all the way to the assembly but run this one wire separately. Are you certain this wire isn't in that harness? Sorry, but I don't have the wiring diagram.

I don't need the wiring diagram; I've held the harness and it only connects to three lamps, as previously described.

I just returned from looking at my harness (driver's side rear). It makes 5 connections, 4 in a row (to lamps it appears) easily visible next to the harness and a 5th near the top of the assembly right behind the LED array. You can only see the 5th connection with your head on the floor an a flashlight point toward the top of the assembly.

Well, I'll make sure the mechanic is told to check that connection before installing a whole new assembly. An hour of labor is surely less expensive than that assembly.

Put your fingers around the harness and slide your hand upward past the four easily visible connections. About 3" above the top visible connection you will feel the harness turn sharply toward the lamp assembly. If it is loose or disconnected you may be able to feel that. This test will take less than a minute of your time.

Thank you, I found the connection, but it is not loose or disconnected.

When this is fixed, let us know what the problem was.

On May 29, 2009, part number 81551-47071, the right side lens and body was replaced. It is reported that the mechanic checked the LED circuit and "IT IS OK". The part cost $186.88 with labor of $52.50.

Sorry, I can't provide better information for those seeking to avoid the same problem; there just isn't any.

Thank you for your assistance, Was Istoben.

Cripes, they sure get a lot for car parts. Did they give you the assembly they removed? It would be interesting to learn what caused the LED array to fail.