funky electrical, won't start now... (1 Viewer)

[romey]

hi folks,

hoping some electrical guru's can help this newb out. been reading another post on a 40 not starting.

so here are the deets/symptoms:

-78 fj40 with a push button ignition switch (no key)

- owned for 5 years, no electrical issues since

- just got gauges installed (water temp, engine oil)

- drove truck home, all was okay.

- decided to clean tidy up some exposed wires in the bay with some wire covers.
nothing disconnected, just covered and ziptied

- gauge cluster still needed mounting and i had to move one gauge over to the middle to make both fit in the old tape deck space

- disconnected ground/ignition/sending unit wire, moved oil gauge over and reconnected exact same way

- tried to start and then nothing, not cranking at all

- noticed the ignition was left on when i was swappin wires on the gauges

- thought maybe i drained the battery (maybe 20 mins with it on) but i have head lights and horn

- i did notice that i have NO turn signals with the ignition on (high beams, brake, tail light working)

- for some reason, while i was tinkering and trying to start, i got lights (in gauges) and the 40 started, this was in the driveway so i just drove the truck in the garage and called it a day.

- next day, fingers crossed, tried to start and nothing (still have head lights) but i did notice the horn wasn't as strong or it would go strong then a weak fart sound not much like a horn, then a strong horn again

- while tinkering out of the blue got lights in the gauges again (not sure what i did) BUT still won't start

- tested fuses, top 3 works on both ends of the fuses, but bottom 3 dont work on either side (i think 20A and 10A and a little shorty fuse at the very bottom). pulled fuses out and tested over battery/+'ve and they work fine

- also replaced a 30A fuse from the battery to ignition (while covering wire/inspecting fuse, i dropped the fuse on the ground, it also had a bulge in the fuse i noticed, tested it over the battery and didn't work, replaced with another 30A fuse which worked, retested with tester light and it still works)

what'd i do when i was monkeyin around with the wires???! arrrgh!!

fry the insides of ignition switch? is this why the lights in the gauges are somewhat going on...?

i have a marine deep cycle battery, could 20 minutes of ignition on (not knowing) enough to weaken the battery to at least have lights but not enough juice to crank? it doesn't crank, not even a ticking sound attempting to crank, just blank when i try to start...

- oh yeah, tried to boost and still nothing...

ground on gauges work, sending unit lines from both gauges look fine, one wire from gauges i believe goes to the ignition button.

not sure if i did this right, with tester light/grounded, i touched the igntion wire to the gauges and with the igntion on...no light...i pulled the ignition switch to inspect physically but no loose wires or broken solders... is it busted inside?

what else can i do to try and diagnose?

please and thanks!!

 

[JohnnyC]

IMHO there is a bad connection, sometimes connecting and sometimes not

check plug connectors for corrosion and for loose connections... clean up grounds and battery terminals and starter wire contacts... thats where i would start IIWM

 

[pavieSD]

Did you have the battery disconnected while you were messing with the gauge cluster and wires? I believe the gauges are always hot regardless of ignition being on or not, so it's possibly you caused a short and melted some wires before the fuse block.

 

[Pin_Head]

Bad ignition switch?
Why else would you need a push button for the starter?

 

[romey]

thanks for the replies fellas! push button was already there when i got the truck, it's worked fine since 2008.

battery was NOT disconnected when i was monkeyin around, slipped my mind, doh!

ignition was on for about 15 min. during

but no sparks and no melting/smoking smells, and really, should have notice it right away if i touched anything while removing terminals behind gauges...

so i notice one teeny thing... i have a 30 amp fuse from +'ve/battery. which i replaced/mentioned earlier. i tested the fuse and the wire just away form the battery, and got a light, so good.

but that wire is taped on to what looks like a ghetto household wire like the ones you use for old lamps or extension cords/clear. i jabbed that with the tester and nothing... that might be it, fingers crossed. i think that leads to the ignition switch... (maybe i kinked it too while zip tying and wire covering...)

and maybe combined that with a drop in voltage in the battery...? going to grab a volt meter (although we couldn't boost it either...but bad wire somewhere anyway).

will report back.....

btw, this is really my first electrical gremlin issue so i thank you all for your patience and advice! reading up some stuff on toyodiy and youtube, etc... trying to get some learnding done and get edumacated...

 

[Pin_Head]

It is pretty hard to offer useful advice about a custom wiring system we don't know about.

All I can say is install a known good battery and turn everything on and look for power with a test light at all the different important devices, like the + side of the coil, the F terminal of the alternator, fuses, and all the other things like turn signals, lights etc. Report back anything that lacks power that should have it.

 

[romey]

thanks pinhead! i'm hoping it's just isolated/related to the ignition/switch and when i messed with the gauge wires.

will see how it goes...

 

[romey]

Well, I think its fixed. Ignition switch was probably fried when I left it on and didn't disconnect battery. Also discovered that switch was only a 3 amp switch. Replaced with 20a switch n got lights and she fired right up!

Battery was at 12.59 volts so no drain.

Also found faulty fuse link for what was actually a wire to fan motor not ignition. That was mated to a ghetto household ac wire which might explain buldging of 30a fuse. Even though there was continuity I replaced with proper wire n will get new fuse holder.

So I learned stuff which is great. Thank you all for the tips!

 

[romey]

just a small update. i have fan power back too, not that i need it in this heat! lol.

based on: ghetto houshold AC wire to fan motor AND a 30A fuse which i noticed a bulge on, is it safe to say that the fluctuations in the current through the crap wires and the too high amperage of a fuse caused a piece of the fuse holder to crap out?

i replaced both wires and am using a 20A fuse for the fan motor/switch. is this acceptable?

also, anyone know the size of the fusible link? i only have one and i couldn't get it on the FSM (and saw tripple FL's on the manual) but didn't tell me the gauge.. i've read 20g for the FL, would that be a safe bet?

in my excitement of getting ignition working, then trying to reinstall the switch on the dash, managed to zap a wire and felt the FL heat up, it was just for a couple secs, idiot! everything still works but i want to be safe and have a new FL link installed.

i heard 14g is too thick...so 20g fusible link?

cheers.

 

[bj40green]

Here is a copy of a text (in green) which I posted a few days ago in another thread.
If you still have the OEM Fusible Link you can find it in the table below.

In case you want to go the DIY route;
Here is the table for Toyota Fusible Links

mm²-Code--Color-------AWG
0.3----P----Purple------22
0.5----G----Green------20
0.85---R----Red--------18
1.0----GR---Gray-------17
1.0----Y----Yellow------17
1.25---B----Black-------16
2.0----L----Light Blue---14

So if your FL is Gray, it means that the (copper) core is 1.0 mm² which is equal to AWG 17, which is not a commercial wire size so I should pick AWG 16 for replacement.

For more info about Fusible Links(◄this a link)

Rudi

 

[romey]

ahh, thanks for that bj40green! it's lookin like a gray wire or a dirty black, lol. okay so a awg 16 or 16 gauge will suffice looks like i'm in between grey/black anyway... guess i'll just use standard crimp on connectors on either side and hopefully that'll do the trick..

 

[romey]

amazing write up! thanks again!! it's members like you with great detail and info that really make this forum. saludos!

 

[romey]

btw, i've come across 20g for FL's for 40s... i know it's thinner...so safe to assume that this may still work and that it'll just be prone to burning up sooner? i mean this would be better than a 14g which could/would increase the chances of melting circuits down and NOT get the job done...

i've also read 6" and 9" lengths for this stuff and yet my stock one and the one's i see in pics look much shorter. is there some equation to follow with the lenght of wire and its gauge??

 

[bj40green]

Depending on model (BJ, FJ, HJ), year and accessories different FL's are used.
That's why it's easier when you have the OEM Fusible Link to check the color code.

6 inch is fine. 9 inch to bridge the distance if necessary is no problem

Rudi

 

[romey]

awesome! thanks Rudi! think i saw a 16G FL for a "chevy" at napa.

also read somethin about it really preventing a looong term/slow short or burn, so i think i should be fine with that very quick zap and warming of the igntion switch (20A) and FL.

cheers.

 

[Coolerman]

Great list Rudy!
The color code chart posted is for TOYOTA fusible links only! The fusible link wire I sell for my kits is gray and is 14ga. (2mm)
My research shows that you should use a fusible link that is four sizes smaller than the wire you are trying to protect. The main wire in a 78 is a hair larger than 10ga so a 14ga link is what I use in my kits.

 

[bj40green]

Great list Rudy!
The color code chart posted is for TOYOTA fusible links only! The fusible link wire I sell for my kits is gray and is 14ga. (2mm)
My research shows that you should use a fusible link that is four sizes smaller than the wire you are trying to protect. The main wire in a 78 is a hair larger than 10ga so a 14ga link is what I use in my kits.

Thanks Coolerman,

Yep, the list is for Toyota only. I deducted these color codes from several Toyota wiring diagrams as you can see in this tread -► https://forum.ih8mud.com/diesel-tech-24-volts-systems/526232-fusible-link-one-my-78-bj40.html

Here is the full list from that thread. The difference is always 4 AWG sizes.

Fusible Link..................Protects circuits with wire size
mm²....AWG...................mm².....AWG
0.3.......22....................0.85......18
0.5.......20....................1.25......16
0.85.....18....................2.0........14
1.0.......17....................2.63......13
1.25.....16....................3.0........12
2.0.......14....................5.0........10
3.0.......12....................8.36........8

Rudi