Blown turn fuse driving me mad! '99 Prerunner 3.4L

Hi all! I've stumbled onto this forum looking for Info and tips on my truck several times and always found useful posts that solved the issue, but this time I need help!! Sorry if it is a long read....

The Problem:
My 99 3.4L Prerunner has taken to blowing the turn fuse repeatedly over the last 2 weeks and I cannot track it down. Initially the hazard/horn fuse was blown also but that didn't recur so I'm just mentioning it FYI. It may have been blown for some time as I rarely use either device, and I have a vague recollection of the horn not working several months ago.

The fuse blows during right turns, usually but not always as it self cancels- meaning it blinks fine for several seconds up to 1 minute. It only does this when moving, I can turn lock to lock in the driveway with signals or hazards flashing and get no issues but turning the corner a few feet away does it usually. Lefts seem to be fine.

What I've done:
I've covered most of the easy stuff- new bulbs front and rear, removed the trailer light converter, cleaned contacts everywhere I could, pulled the hazard switch out to check for shorts, etc...
I've also removed the lower dash and pushed/pulled/moved every wire I could reach with no effect. I have pulled and inspected the flasher. I have crawled around under the truck tracing and disturbing the harness wherever I could and especially at attachment points, looms, zip ties, etc...

So far I have never been able to make it happen!
I am going insane over this and I have to drive the aging beast 100 miles down to Portland OR in a few days so turn signals would be nice. I am thinking about getting an 10A manual reset breaker and bypassing the fuse so at least I can drive it around and see if I can find a pattern without burning through another 20 fuses.

At this point I am almost reduced to throwing parts at the problem to see what happens. I will replace the flasher just because it is cheap, although it seems to work fine. I also want to make a jumper to bypass the flasher. It is hard to test for bad grounds while it flashes. I have not opened the steering column yet but that is on my list.

Anyone got any ideas I've missed? Usually when I get this stuck at work another tech will point out an obvious or simple thing and I'll feel like an idiot for over-thinking it.
If you've read this far, thanks; and please do make me feel like an idiot if you have any idea that might solve the problem.

 

Well if its occuring when you turn right , I'd start looking for some pinched/bare wires along the steering column, from turn signal switch on out all the way to the fuse block, by the kick panel & under the hood

 

I would try replacing the turn signal switch itself . Fairly easy to do, and cheap if you go used, even cheaper from a picknpull.

 

Thanks for the responses!

Spent the last 2 hours following the harness from stalk to each corner of the truck with no results. With engine on and right signal flashing I pushed, pulled, and moved the harness everywhere I could get to it. I found other things that I didn't want to see like a leaky PS hose but not what I was hoping for. I repeated much the same with my DMM looking for shorts to ground.

I pretty much hosed the switch down with cleaner while moving it from position to position with no change, so I may have to go the parts route.

I think I will try to get a used switch and maybe the multifunction relay at the fuse block from a local Toy parts yard, assuming they have them. I haven't priced them new but I bet Toyota wants $$$.

 

You can count on it....

 

Any tips for getting the turn switch out of the column? I only saw a few screws through it today>

 

Id start unplugging stuff in that system till it doesnt blow anymore?..

Does it have ANYTHING aftermarket? Sound system remote start lights foglights ANYTHING?

Edit-what im thinking if YES is that a PO or you could've done some shabby wiring and causing trouble...

 

There is your wiring diagram for your turn signals. Power for turn signal comes into terminal 10 of the hazard switch, and then out terminal 7 to the turn signal flasher. From there it heads out terminal 1 of the flasher, to terminal 2 of the turn signal switch. On a right turn the power then exits the turn signal switch at terminal 3, where it meets up with the splice that then distributes the voltage to the front, rear, and dash indicators.

Since it blows intermittently, it will be difficult to chase down. I would suspect possible water intrusion into one of the turn signal bulb sockets that is causing a slight short. Remove both front and rear turn signal bulbs and inspect the sockets.

 

I got it used at 16,000 miles in 2001. The PO did wire in a 50 amp line from the battery to a plug on the trailer hitch but I already disconnected that with no change. He/she used wire nuts and tape - it lasted 14 years but still odd to see household stuff under your bumper. I'll have to look at the sketchy ground they made at the rear, thanks for getting me thinking about it.

As for aftermarket I put a stereo in about 2004, with a small amp (grounded to frame and powered off battery w/30amp fuse) and sub but nothing touching that circuit. I did do it myself so it doesn't hurt to revisit that wiring. That is it, no pretty lighting or anything. It's really pretty stock.

I'll try yanking the fuses on both radio and amp, it isn't hard to do.

Just FYI I forgot to mention it is at 140,000 miles now and this is the first issue that took more than a few hours to solve. I did a starter 3.5 years ago and the timing belt and water pump a long time ago. Averaged over time this truck has been very easy to own. I spent more time under my Unimog in the first 2 weeks than this truck has needed total.

 

Unplug the wirign for the turn signals headlights see if it changes that'd eliminate any water intrustion like said above(good thinking)...

good luck!

 

Thanks for the schematic, it beats the Haynes manual all day. I've been in every light (except dash), and none has been wet or even shown signs of significant moisture other than left rear where the trailer converter plugs in. There was slight green corrosion on the tips of the terminals there but they cleaned up.

Do you know off hand what the letters in the ground symbols on your schematic mean, IG, EA, and IE? They are not on mine.

I can't say it is truly intermittent since it will happen 99% of the time I use the right signal while driving but it is not reproducible; which is really frustrating. I can only address anything I randomly find then drive around until it blows. Today it made 6 turns during one test before blowing; a new record. But back at my house it flashed for 1.5 hrs while I screwed with the harness and various plugs and never blew.

I need to pull the hazard switch again in the AM and just bypass it, as it still nags me that the horn/hazard fuse was also blown the first time I blew the turn fuse. I can at least eliminate the switch.

 

I don't know what those initials mean for sure. I never really dug into it. Interestingly enough it only happens while driving, so I am curious is suspension movement, or harness movement is the trigger. It is an interesting problem to say the least. I am working on a Chrysler at the shop with an intermittent slow short in the ignition fuse. 14 different components get power off that fuse, and it doesn't ALWAYS blow the fuse fast, so it has been a bear. I have been working on it for about 3 days now, off and on through the day. I have the short down to two circuits, with 4 components each on them. I'll get there and so will you.

 

After another round of playing I am reasonably sure that it is the column switch. If I don't fully engage the switch and just hold it up enough to flash the blinker I haven't been seeing the problem. I am taking a long drive shortly so I'll have time to test that theory. I don't get why that would only be an issue when in motion but it is the best idea I have right now.

Unfortunately the local used Toy parts yard is closed on Sundays or I'd just pull a switch and change it. I can probably find it in Portland tomorrow, these trucks are really common out here.

 

Are there any other issues? Does the cruise, horn work or air bag light on? If you got issues with any of the things I listed, you could have a bad ribbon cable or as we all call it clock spring harness.

 

Nothing else obvious is going on. Except what is probably just a loose speaker wire, but I think I did that while trying to find this. It doesn't blow the radio fuse but once in a while I think I hear the right rear speaker drop out.

I spent several hours last weekend messing around and a few patterns seem to be showing up.
1) It's weird but it seems that my butt needs to be in the driver's seat. I was able to make it blow sitting still twice while rocking the truck from the driver's seat. Those are the only times it has blown sitting still. Might have been coincidence but I need to check main and remote power to the amp that is mounted beneath the seat. Wiring is under carpet and maybe has gotten pinched under seat or rubbed bare. The amp is not powering the speaker mentioned above.

2) A few times I was able to make it blow as soon as I flipped the stalk all the way to on and the tilt steering was all the way down. Inspection of the harness doesn't reveal any spots that the tilt mechanism even comes close. SO that again may be coincidence.

On the positive side, I installed a auto reset breaker in place of the fuse after I changed 50+ fuses. Also changed the blinker after seeing 8.5v going up to stalk while running, returned to 12v after that. However it still blew fuses in Portland / and tripped the breaker on the drive back to Olympia Tuesday.

However for the last few days it has not tripped the breaker at any time that I have noticed. The signal flashes until it self cancels every time. So until life backs off a little or something outright fails I am going to ride with it.

Thanks to all for the responses, it is really nice to have a resource such as this forum. Feel free to post any ideas you have and I will update when I get back on this problem.

Drew