Mechanics

BLOWN TAIL LIGHT FUSE

2005 Pontiac Vibe • 75,000 miles

Can the DRL relay on a 2005 Pontiac Vibe cause the tail lamp fuse to blow? The fuse keeps blowing but the headlights come on as expected when you start the car (DRL). Turning the headlights on when the car is off via the stalk also turns on the headlights. The dash light that indicates that the headlights are on at night (as opposed to just the DRL's) does not come on as expected during the dark but, since headlights are on, I can assume that this is still the DRL's active. I pulled all the bulbs, they are good. No changes/modifications have been made to the vehicle. All other fuses are good both under the hood and under the dash. The emergency brake is never used but I pulled it several times because I was aware of the switch there.
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Robh693
December 12, 2011.




Lets start with what is the fuse labeled that is blowing?

Saturntech9
Dec 12, 2011.
It is the 15 amp Tail light fuse located under the dash. I replaced it with another 15 and that also blew. A 20 amp fuse also blew, then against my better judgement, I put in a 30 amp and quickly turned on the lights to see if they worked and they did, that fuse did not blow and I removed it.
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Tiny
Robh693
Dec 12, 2011.
So it blows the moment you turn on parking/running lights?

Saturntech9
Dec 12, 2011.
Yes, instantly. As soon as I turn the stalk to the first position (parking lights) it blows. I can continue to the second position and that still turns on the headlights (but no parking lights) (with the car off, if I had the car running, the DRL's would be on and I couldn't tell if it was them on or the actual headlights).

Tiny
Robh693
Dec 12, 2011.
Usually a instant blowing of the fuse is a dead short on the power side. Do you have a multimeter to do some testing?

Saturntech9
Dec 12, 2011.
Yes

Tiny
Robh693
Dec 12, 2011.
Remove the fuse one side of the fuse holder will have power the other side wont. Side that has no power is the side you need to check. Put the multimeter on low ohms scale setting then ground the black lead of the meter. Then use the read lead to check the nonpower side of the fuse holder for a short to ground. Then turn the switch to the on position for the parking lights and see if there is a short to ground.

Saturntech9
Dec 12, 2011.
I got a reading of 172.

Tiny
Robh693
Dec 13, 2011.
Alright some of that can just be reading to ground thru the element of the blubs. There is basicially a few ways to go about this one to tearing apart the whole car looking for the issue.A very timely and not really the best choice. There is also to buy a circuit tracer which is about the best choice you would hook it in where the fuse goes it reads out out on the box if you have a open circuit or short to ground. Then you use the wand to follow the signal which is sent down the wires. Where the signal stops is where the short is or if you were tracing a open it would stop. Then there is the spliting the circuit up into sub circuits with small 5amp fuses and see which fuse pops and then you can narrow down which part of the sub circuit has the short to ground. Then you will have to start tearing the car apart looking for it. Non of the three ways mentioned is going to be easy the easiest way is with the circuit tracer. Which way would you like to try?

Saturntech9
Dec 13, 2011.
Since I should only be dealing with the 4 corners of the car, and it is a bare bones Vibe, I'm going to trace the wires back from the bulbs.

Tiny
Robh693
Dec 13, 2011.

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