Instrument panel fuse in Highlander keeps blowing
 

This regarding a 2002 Highlander v6.

Recently I realized that the instrument panel lights in the area behind the climate control knobs, the hazard light button and also the gearshift area were no longer illuminating. At first, I believe that this was due to the age of the vehicle and that the bulbs in question had burned out.

I obtained the appropriate replacement bulbs from my Toyota dealer service department. I then proceeded to install them myself carefully. They did not work initially, but I thought further about the problem and discovered the secondary fuse panel within the passenger compartment next to the drivers wheel.

After opening this panel up and looking at the fuses, I consulted my owners manual for the appropriate that might control the lights in question. This was identified as fuse position number 45 with a 7.5 amp fuse. I pulled this fuse out and discovered it was broken. So I replaced it with an identical fuse and proceeded to start the vehicle. The instrument panel lights which I had replaced now lit up.

However on a subsequent startup of the car the panel lights in question did not come on. I opened up the secondary fuse box again and found that the fuse I had just placed at position 45 had burned out. I was surprised by this as it was only a span of 10 minutes from when I had installed it. I tried some additional fuses in there and received the same result.

I went through one fuse and checked it step by step after insertion, activating and cutting the ignition and lastly turning on the headlights. The burnout in the fuse occurs not when it is installed, not when the car is started, but rather when I turned on the headlights. That is when the fuse burns out.

Everything else in the vehicle is working without a problem. I am just at a loss to figure out what to do next with regards to fuse number 45 and how to identify what the problem may be there with regards to the headlights somehow causing the fuse number 45 to burn out.

What should be my next step in this area? I am not sure how to go with further diagnosis.

Thanks!

Not ever having seen one of there vehicles I can only guess.

You have a short or you have added more load to this circuit causing it to draw more current then the fuse can handle.

Have any after market electrical devices been added to this circuit??

A short means the positive wire is touching something grounded most often causing it to arc which causes the circuit to draw more current then the fuse can handle.


In most other Toyota` vehicles these lights are also tied into the tail light circuit .

Are your tail lights also not working??

So some place in this circuit you have a problem.

My tail lights, parking lights, head lights and dome lights are all working, as is my clock and speedometer and odometer. The only things that werr changed in the vehicle were installation of replacement stereo head unit and slightly more powerful speakers to handle the output from the speakers.

There is a ground wire from the back of the stereo unit which I attached to the metal frame around the firewall. Could that be the source of the problem? The stereo works fine and doesn't run off the same fuse.

The problem for the panel fuse comes when I turn on the headlights, not before. The fuse gets through ignition fine as I determined by my step by step approach.

I did some further experimenting. First I put in a fresh 7.5 amp fuse. Then I removed the detachable face of the stereo head unit. I then turned on the vehicle, the panel lights (emergency hazard button, climate control backlight, cigarette lighter perimeter and gear shift illumination) controlled by fuse #45 all lit. I then turned on the headlights, the panel lights remained lit. My assumption is now that the stereo head unit ground wire is not sufficiently grounded to metal. That is probably the source of the fuse burn out earlier. My question is where should I put the ground wire from the back of the stereo head unit. I don't have that much wire to work with, perhaps two feet.

Hi rushw,

I don't have the '02 Highlander schematic diagrams, my truck is a '12 4runner... close though. your problem is in the 'Instrument Illumination circuit'; 'Accessory meter assm'. The HU is grounded internally (Through the wiring harness) so I don't think that's your problem. The problem exists 'usually' when you have the parking/headlights on, correct? The Instrument Illumination circuit is responsible for bringing on the Back-lighting on the accessories e.g., Compass, Econo-meter, Radio illumination, Temperature control lighting...etc.

So when you pulled the Head-unit out, the fuse stopped blowing... is that right? You can figure out which accessory is at fault by eliminating them, one-by-one i.e., disconnecting each device from the lighting circuit (checking the fuse) and putting it back in as you go down the line. It might be a good idea to get that wiring schematic online just for reference. I have all of the 5'TH gen 4Runner wiring diagrams; they're not exactly the same as the Highlander, but most Toyota's are formatted similarly wrt electrical systems, so I may be able to answer any questions that you may have after you have a data sheet to work from!

Cheers!