SoCal4Running

EDIT!!!!! I was wrong it is not the 7.5 Charge fuse but the 15A Eng fuse! Sorry

OK, I have searched and searched all over the Interweb and have not really found much info on my specific situation.

I have a 86 4Runner with a 22re/W56.

I was parked on a hill and decided to Bump Start (NOT JUMP START) the truck by rolling down hill and dropping clutch in 2nd gear with the key on.

As soon as it fired the dash went DEAD. I was only a few miles from home so I decided to get on the road and go for it. The only instrument that worked obviously was the speedometer.

Soon I realized my turn signals also do not work and upon arriving at home found out that my rear window also does not work now.

I have a stock Supra Alternator in the vehicle that was installed New after this all happened. Was a mod I wanted to do for a while and figured the old alternator was the issue.

I got the new alternator in which uses all factory wiring and changed the charge fuse.

Long story short, the fuse keeps blowing at random times not related to any specific use of the turn signals or rear window.

I have tried both a 10A and a 20A (I know not a good idea) and they still blow.

Any ideas where to check?
All the power wires appear to be ok but am going to upgrade soon to new thicker wiring, was just wondering if anyone had a sure fix solution.

Also battery which is a new 900CCA will die in a day or so if I dont start the vehicle.

Thanks!

Co_94_PU

iTrader: (-1)

Turn all the accessories off, pull the fuses and start probing them for shorts to ground with you DMM. Ideally you'll find one that has little to no resistence, this will be the one with the short.

You likely shifted something out of place under the fuse box (Relay block #2, the one under the hood).

wyoming9

iTrader: (1)

Just what fuse keeps blowing??

Now I am looking at the 87 electrical manual I think 86 is the same but I could be wrong

The 7.5 amp charge fuse gets power from the 7.5 amp ignition fuse.

it pretty much just lights the light on your dash that lights when you have a voltage issue.

nothing to do with turn signals or the rear window the rear window gets power from the 15amp Engine Fuse and the 20 amp circuit breaker.

I think the fact you compression started the truck when this happened was just one of those things

bare wire someplace shorting out more then likely pinched or rubbing someplace

SoCal4Running

Thanks for the tips... Keep'em coming.

I replaced the 80A fuse in the fuse box under hood. I had a new one and the old one even though good was looking crusty inside.

Going to order up some new main battery wires and do that next.

The fuse that blows is the 7.5A in the drivers side kick panel. BTW.

Co_94_PU

iTrader: (-1)

Need more symptoms, and a clear answer on which fuse(s).

Engine or IGN, both are 7.5A fuses in that block. Granted this book isn't the greatest because it says earlier it's a larger fuse(15A). IGN Should shut off the EFI relay, Engine shuts off various lights and the alternator.

Do you have any lights in the dash not functioning when you first turn the key to on and they light up for the bulb check? Bulb failure in the backup lights? Checked for a trailer harness short?

Have you ever been into the dash far enough to see the back of the guage cluster, did it have the "bulb check relay" on the back? probably a bad idea to bump start those systems since IIRC this uses the STA(starter) signal, but I'd have to go back thru the sr5 gauge swap thread to familiarize myself with it's function.

RAD4Runner

Agree with Wyoming ^^.

First of all, fuse values are there for a reason. One should never Upgrade fuse values

You sure it's your Charge fuse (7.5A) that's blowing, not the Engine fuse (15A)? Charge fuse is in fuse block in engine compartment, near battery. Engine Fuse is in driver side kick panel.

Charge fuse does not carry much load, really. It's just a path for "L" fault output of alternator to provide ground to negative side of charge & brake light when there's an alt fault.



Your dash lights (combination meter), rear window, PPS computer, ECT computer, backup light and IG input of alternator share the Engine fuse (15A). Checked your backup light and wiring? Switch or wire may be shorted to ground. It could be intermittent because wire vibrates. I haven't looked at 4WD (Transfer) light switch, yet. Might also share same circuit.



When insulation of backup light wiring eventually wears out from rubbing against transmission, it will short to ground and blow the Engine fuse.

Toyota must have better mechanical engineers than electrical engineers back in those days. That explains 22RE-liable but poor circuit design.
Another example is this case. Why share a common fuse between critical circuits (PPS/ECT computers, and alt IG inputs) and non-critical ones (backup light, rear window, dash light), especially if the weak point is the backup light wiring?

SoCal4Running

Ok major Edit to the post here and let me start off by saying sorry!

It is not the 7.5Charge fuse but is actually the 15A ENG fuse.
I do not have the fuse box cover and stupidly assumed it was the Charge fuse as it powers down the alternator.

Side note, I installed the 2 Gauge Pos/Neg wires today and am sourcing 6 Gauge for the alternator as well as new solder Lugs for it.

RAD4Runner

I thought so. Now more reason to check ^^

SoCal4Running

Pretty sure I have this fixed now.
Found this today.


Its the reverse light switch connector at the Transmission.

Also found my parasitic draw issue is with the Hazard/Horn so just pulled fuse for now. Horn doesnt work anyways and cant remeber the last time I ever used my hazard lights.

RAD4Runner

Looks like you found it. Where was it shorting to? Make sure you inspect the whole wiring run. Got picture of how that connector is secured? On mine it vibrates as in video.

What? Horn doesn't work? I like to keep mine functional; using horn more than the brakes means less wear and tear -LOL!

SoCal4Running

My connector was not restrained at all at the trans. Suprised they don't use a spring clip like at the distributor for its wire. The plug was being pulled verticle up the trans and the open wire was most likely touching at the top of the trans.

The connector also was completly full of oil from my Valve Cover leak (next project). The part that is connected to the trans can is kinda hollow inside and this filled up.

Thanks for trying to steer me in the correct direction from the beginning.

RAD4Runner

Cool! Yep, back in those days, Toyota must have had better mechanical engineers than electrical ones. Nowadays, I don't know- Don't even feel like looking into those complicated cars.