Replaced dead alternator with 100-amp, gauge fuse keep blowing (1 Viewer)

[jdlobb]

My alternator died recently and I replaced it with a 100-amp version. Everything runs fine, turns over perfectly. But the 15-amp fuse to the gauge cluster keeps blowing as soon as I start the truck.

1998 100-series

Thoughts?

follow-up question: I did re-charge the battery with a plug-in wall charger before putting it back in. Is it possible this might have something to do with the problem? If so, how can I test for it?

updates:

The fuse blows out as soon as the key is turned to the ACC position.
The battery tests at 12.47v at the terminals
No other fuses in the cab or in the engine bay are blowing, just the 15A that runs to the dash gauges


The only wiring that was touched during the install of the new alternator was the ground on the alternator and the wiring harness that goes into the alternator. Could either of these be the failure point?

 

[dogdaysindurham]

If the wall charger overcharged your battery, it could lead to blown fuses. But a bad alternator can also spike the voltages leading to blown fuses.

So there might be other fuses that are blown and need to be replaced, have you checked all of the fuses in the engine bay and the driver side kick panel? I would check to see if you have an error code thrown?

Some culprits in prior threads were the towing hitch wiring harness, a blown VSS (Vehicle Speed Sensor) which manifests with the P0500 error code.

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Good luck!

 

[e9999]

Is it first thing when you mechanically start the engine, or first thing when you turn the ignition key on? Former is likely something to do with the alternator. Latter, much less likely I would think.

well, not surprisingly, the first thing to test for would have to be the voltage on the battery with and without the alternator generating. It'll tell you right away if the voltage regulation is OK or not, I would think. If the alternator gives you more than 14.4V or so, there is a risk of damage to the battery as well, so I would be cautious about that.
You may want to find out what kind of alternator it is, what kind of voltage regulation it uses, voltage limits etc.

If you have doubts about the alternator or if it's temperamental, and you need to keep driving, there are inexpensive (less than $10) voltmeters you stick in the cigarette lighter and you can monitor the voltage while driving. But better not drive if the voltage is clearly excessive, you really don't want to fry some ECU type gizmo.

 

[jdlobb]

If the wall charger overcharged your battery, it could lead to blown fuses. But a bad alternator can also spike the voltages leading to blown fuses.

So there might be other fuses that are blown and need to be replaced, have you checked all of the fuses in the engine bay and the driver side kick panel? I would check to see if you have an error code thrown?

Some culprits in prior threads were the towing hitch wiring harness, a blown VSS (Vehicle Speed Sensor) which manifests with the P0500 error code.

Good luck!

it appears to only be the single 15A fuse running to the gauges. None of the other fuses under the steering wheel or in the engine bay are blown.

Narrowing down the issue, i believe the fuse is blowing when the key is turned, not when the engine turns over, as I don't even get anything on the gauges when i first insert the key.

 

[jdlobb]

well I was going to check the voltage, but somebody (me) didn't turn off their volt-meter last time they put it away, so until i can go get a new 9V battery tomorrow, i'm up a creek.

 

[dogdaysindurham]

I can't seem to find a digital copy of the Electronic Wiring Diagram in a sep. pdf.

But these are a mix of pdfs that are for the 100 and 105 series Land Cruiser.




Meet Google Drive – One place for all your files

 

[e9999]

If it blows up right when you turn on the ignition and the battery is not at over voltage, it has probably nothing to do with the alternator I would think. But maybe some wiring got messed up when installing it?

 

[dogdaysindurham]

Here is Body Electrical Section of the FSM:


I could find this EWD for the 05 Tundra:

Hope this helps.

 

[dogdaysindurham]

EWD for the 100 series:

 

[jdlobb]

I got the replacement 9V battery for my multimeter. Can anybody tell me what, other than the battery itself, I can or should test to try and narrow down the issue?

 

[erse]

 

[jdlobb]

Can't find the issue. Going to have to have a mobile mechanic come out early next week. fml

 

[2001LC]

Whenever a problem arises after doing a job, like your alternator replacement. I go there first. This includes anything touched. If aftermarket alternator, rebuild OEM, or non standard to your year. Then it's not out of the question, it has an internal short. Or short if wiring modified to attach to it, or pinched in mounting brackets of alternator somehow. Or it's not the same wiring configuration in harness block of alternator.

If that all checks out you've a short, somewhere along that fuses circuit that happen somehow at same time. Not likely but not impossible. In TIS you can click on all effected systems in wiring diagram starting at that fuse and they highlight. Then look for common points. This is a very useful tool to narrow down search for short.

 

[jdlobb]

Follow-up. ended up taking the truck to an electronics shop, because I needed to take a long road trip in it. They found the short in the harness at the alternator, which required the alternator and PS pump to again be pulled all over again. $300 in labor later and it was all sorted.

Maybe or maybe no related, but 2 weeks later, the day I was heading home from my road trip to New Orleans (made the trip down perfectly) I started the truck after loading it to head home, and only half the cylinders were running, check engine light FLASHING at me like.

Limped to pep boys, and had another $970 in work done to replace ignition coils, fouled spark plugs, and i don't remember what else off the top of my head.

I swore to myself if the repair bill was more than $1000 I was selling the truck for cash on the spot and renting a car to get home. But it wasn't meant to be.

Home now though, trip back went just as good as the trip down.

Regardless, i'm staying out of the cursed thing until I have the last repair paid off on my credit card and can get it to my uncle's Toyota dealership for a full looking-over any any additional preventative work that needs to be done.

Came within $30 of saying goodbye to that sweet Land Cruiser life forever.