Philbert

iTrader: (2)

I'll admit it. Total bonehead move.

I've had this parasitic battery drain for over a month and need to jump it every time I drive it. Was going to get it into the garage tonight and take a look....so I went out to the curb in the rain, pulled up my car in front, started hooking up the cables like always, and "it won't start". went back around to the hood, smelled something, then realized what I did, and took off the cables ASAP.

truck had ZERO power at that point, though right before I realilzed my mistake, I tried out the headlights (while the donor car was running)....they worked, as did the brights, but no parking lights....hmmmm I thought. Then I realized I had reversed it...now back to that.

So, I took the cabled off and got the flashlight out to peek around. Fuses in the engine bay looked fine, except the 80AMP fusible link, which was completely shot.



I have not yet checked the in-cab fuses, but will tomorrow when light (and hopefully not pouring).

To your knowledge, does the 80 AMP fuse do a good job of protecting the rest of the system (alt, etc) on these trucks, or am I likely in for more of a shock here? The 80 AMP fuse is about $10 at a parts store I think?

Thanks,

Phil (still kicking himself for such a bonehead move....)

justin_4runner

yeah the 80 amp one does portect it all, a couple other guys that have done thins fixed the 80 amp fuse and everything was good, just chock it up to your oops next time ill think before i do... i know we all have that list....

xxxtreme22r

I did this to mine, but hooked the battery up backwards not jumped it, I fried the alt in doing so. I never blew the 80 amp though. The 80 amp doesn't protect everything electrical in the truck though. You can see what it doesn't protect by looking at the electrical schematics in the back of he FSM.

Zelephant

Same here, I hooked a battery up backwards once. I was borrowing a battery out of a Corrolla because mine was totally shot, and failed to realize that the poles were reversed. After Googling and and reading horror stories about blown alts and ECUs, I changed the 80a fusible link and also the EFI fuse (make sure you check that, as mine was blown). After replacing those two fuses and the battery that was shot to begin with, the truck started fine! I later replaced the tiny fuse on the back of my radio that had also blown. Incidentally, the borrowed Corrolla battery was also undamaged.

So in short, I'd be very surprised if you did any serious damage. And $10 seems like a lot for the 80a fuse, IIRC mine was $3.

trdwssrs

my cousin did the same thing to my 85' ...replaced the 80amp and everything was fine. note to self: never let people touch stuff under my hood, unless they are qualified.

Philbert

iTrader: (2)

Thanks everyone for chiming in, and doing so quickly!

Been away from the PC for a couple days but wanted to let you know that I replaced the 80A fusible link ($2.99 at parts store), and the 15A fuse for my EFI system (that had apparently also blown, since the engine kept turning over and over but not firing, once the new 80A fuse was in).

Starts and runs...now it's in the garage to address my coolant leak on the drivers side water pipe (torn apart now, patching up later this week).

I also eliminated the parasitic drain I had (reason I had to jump all the time to start)....when I did my autometer gauges over Christmas, I tapped into constant power instead of switched power....DOH! (can you tell I suck at electronics?...). Just need to find a way to tap into switched power at the dash, near the steering wheel...any suggestions?

And, while I'm on topic of gauges and wiring....I wired up my autometer oil pressure and water temp gauges over the holidays....the water gauge works, kind of...I think it's reading low and fluctuating because I've had a coolant leak and the sender is in the upper radiator hose, which isn't getting a full "load" of coolant going through it - more like a trickle.

The oil pressure gauge sender is giving me ZERO reading. I think because it's not grounded (the sender)?

I have this Glowshift sandwich plate installed, with the autometer sender installed in it, and wires running back to the cab for the gauge:



It's made of aluminum, and it has rubber gaskets between where the plate mounts and the block. I've read that oil pressure senders that are NPT like mine are supposed to ground using the threads...but if there's rubber in between (and it's aluminum - which is conductive but not as much as steel?), am I missing a step???

Thanks for any suggestions guys!

Phil

Zelephant

Just tap into either the ON or ACC power wire coming off the ignition cylinder, depending on when you want the power to come on. That's where I tapped power for my fog light relay. Works perfect!

Philbert

iTrader: (2)

Yeah, so, I THOUGHT I had done that when I initially hooked things up...turned out I had hooked into the "always hot" line that goes INTO the cylinder I guess - hence the drain

I'm already embarassing myself in this thread, so....how do I identify the "switched" wire in the same area?



Also, any ideas on the oil pressure sender question?

Magnusian

Test for the one that goes hot when you turn the key to ON/ACC?

Zelephant

IIRC they're labeled on the cylinder.

Philbert

iTrader: (2)

How did I not notice that when I had the plastic shroud off?

Honestly, I would not be asking if I knew how to test I can do resistance tests, but not sure how to test if a wire is "hot" or not, without risk of shorting something out (with my track record this week, you can see why)....

It's been 2 months since I'd hooked it up, but perhaps I had followed the "red" wire on the cylinder, but mistook the "out" line (switchable) with the "in" line (always hot). I'll take another look.

Either way, can you guys simply explain how one (safely) tests a wire for "hotness" using a multimeter? I *need* to learn this

Thanks

Magnusian

Don't need to worry much, just touch the black lead to ground and the red lead to what you're testing.

In the case of looking for which wire is switched power here, turn the key to ON or ACC, turn the meter to something over 12V (like 20 or 100) on the DC part of the dial, touch black lead to ground somewhere (body/frame/motor) and the red lead to each wire. Record which show 12V, turn key off, record which of those at 12V are now at 0V. The voltage you measure won't be exactly 12V, but it should be around there I think. Unless it's supposed to be different, then it'll be whatever the spec is.

Of course, there's also the old-fashioned way. This requires possibly multiple assistants. Ever lick a 9V battery to check if it has a charge, or heard about licking the end of house wiring to see if it's live (don't go licking the wires in your house please)? Same idea, except your assistant(s) insulate(s) you from electrocution.

Philbert

iTrader: (2)

Thanks Magnusian - that makes perfect sense and I will use it to find my wire!

Appreciate it guys!

Magnusian

This is a low current wire, right? You -might- need to switch your multimeter to the 3-5A fused side before testing if it isn't low current, else you'll end up with a fried meter.

Outsane

do you have a multi-meter or a spare bulb socket?

Or you can get a test probe..and connect one end to ground and the other to what you think might be a switched line, keep trying until you find the one that turns the bulb on when the ignition is on...

or go through the wiring diagram

strykersd

Aw, I was hoping you jumped your truck in reverse! Now that could be interesting...

85toyman

iTrader: (2)

Looking at the title, I was hoping to see a shot of you driving backwards and flying off a dirt mound.

Hope that everything is ok and the fuse fixes it.

Philbert

iTrader: (2)

You guys are funny Sorry for the letdown....

truck was fine after replacing the 80AMP $3 fusible link in the engine bay - saved alternator and everything else - whew!!!

Philbert

iTrader: (2)

So THIS is what saved my eletrical system, by taking the bullet all by itself:


$2.99 at the auto parts store...

Thanks guys for the suggestions on how to use a multimeter/test light - while patching up my coolant leak and re wiring my autometer senders (grounding them correctly...) I tried the test light out on the bettery, and YEP! it works just as described. Will tackle the in-cab "switched" wire for the gauges later this week, top off with coolant, and see if this thing finally works - I miss driving it!!

Phil

Philbert

iTrader: (2)

Thanks again Outsane and Magnusian - used the test light to find my "switched" power tap under the steering wheel, and now my (properly grounded in the engine bay too) autometer gauges work great!!