fuse blowing

i have a 2003 tundra 2wd.

recently blew a fuse. with the fuse blown the dash gauges, speedometer, odometer, turn signals went out. also, the alternator will not charge the battery in this condition. i can't find a short but nor have i looked exhaustively. was hoping to get some direction to maybe speed the troubleshooting.

initially, the fuse would blow when i put it in gear. i actually could, with the car running and transmission in P, install a fuse and charge the battery as long as i wanted. i thought i recently had located the issue and the fuse didnt blow for a week. THEN, it blew again but now the fuse blows as soon as it is installed whether the vehicle is in P or not.

does any one have a suggestion?

 

What fuse is blowing?

 

i'm sorry... i should have included the fuse number. it is fuse #23, 10A. it's located on the cabin fuse block and serves the dash lights, meters, back up lights, AC (fan only i think)and a couple other things

 

Do you have *any*aftermarket stuff installed in the truck?

And if you're not the 1st owner, have you inspected carefully all under the dash and in the driver's side kick panel to confirm there was never an alarm installed? Some dealers installed cheap alarms (KARR, SECURIKEY+) in vehicles to sell at an astronomical upcharge.

 

https://www.tundras.com/threads/ultimate-tundra-wiring-diagrams-collection.81448/

I would check brake switch and neutral safety switch circuits first then maybe trailer plug brake

 

I am, i think, the 3rd owner BUT have had it since 2008. Purchased with ~59k miles
It now has 420k. It has been a real trooper. It has no after market but it is a salvage vehicle.

 

There is no security system.

 

Flood damage or some other issues?

 

I'd need to look at the electrical wiring diagrams linked to earlier to understand what circuits are impacted.

To @2mchfun's point earlier: Does it have an aftermarket trailer wiring harness? A lot of people are dumbasses and install those using t-taps and scotchloks, which damages wires (especially exterior wiring) and leads to failures/shorts/etc. We even saw someone on here with a dealer-installed Toyota OEM 4-pin (yellow/green/white/black) harness that was installed with unsealed crimps, which is also a dumbass move for exterior wiring.

 

PS -

I also need to ask, has the windshield ever been replaced?
Are there any cracks in the windshield?

I ask because water intrustion into the fusdebox is SUPER common. And I'm not kidding, pics & pics & pics, it happens a LOT. Water usually comes in from the a-pillar, or the top of the windshield, or from the lower corners of the windshield. Water travels down the wiring harnesses into the back of the fusebox.

 

You could try to see if it blows in the run position to help troubleshooting. In other words, don't turn ignition to start and see what happens. What happens if you mash the brake without a key in it? What happens if you try to start in neutral vs park? Just some ways to kinda narrow it down.

 

YES... the windshield has been replaced at least once. It was done abiut 8yrs ago.

Also YES on the water intrusion. I had to replace that fuse block once due to the original one being fouled up due to contamination and actually smoked a few relays. Maybe i didnt need to replace it but the original was screwed up and i thought it was just easier to replace the whole thing with one from the wrecking yard.

It is possible the current problem is associated from water issues but it doesn't appear to be upon inspection.

 

Does your steering column telescope frequently? Sometimes wires get torn from this action.

 

The most common issue we find with mystery fuse blowing is one of the following:

• Wires are being pinched/rubbed in the least likely place imaginable
• Corrosion inside a connector, more commonly seen in the rust belt
• Bad connection (bad butt splice/wire nut behind radio, that type of thing)
• Water intrusion into the cab as mentioned prior

Taken from the links at the top of the MEGATHREAD, here's the EWD for your '03: https://www.tundras.com/attachments/2003-tundra-ewd491u-pdf.543917/

 

thank you to all who read and offered suggestions.

i had a friend come over. he's actually a service writer for the local toyota dealer and generally a good troubleshooter... a few things were tried with no success. i asked him why the alternator charging would be on the circuit with those other things... dash lights,***meters, etc. he didnt have an answer but said "why don't we unplug the alternator and see what happens."

upon disconnecting the alternator everything worked fine except charging (with a new fuse). put a rebuilt alternator in and presto.... running fine. tomorrow will be the test... need to drive ~75mi .

 

Great news! Also great that you posted the details for others to reference! BTW, welcome to the forum from OKC!

 

Great job trouble shooting. Let us know how it goes with the 75 mile trip.

 

Nice! I never remember if the alternator in the '03 uses the ovular connector or the square connector for the rear of the alternator.

If yours uses the square connector, this is a great time to upgrade to 130A that came with later-year 1st gens with Tow Package, or consider the 150A that came with the Sequoia.

Whatever you do, stick with Denso brand parts from a reputable source (i.e. avoid fleaBay and scAmazon). If you need a part number for any of these, holler.

It's also easy to re-pin the ovular connector into a square connector for a plug-and-play upgrade.

Last time we saw a case similar to this, the affected member found someone spliced his wiring on the positive side of the circuit and the splice had degraded, and was shorting. May be worth inspection of all positive leads from batt to alt, batt to in-bay fuse/relay box, etc.