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86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

clock fuse is randomly blowing

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Old Nov 29, 2009 | 12:17 AM
  #1  
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From: Renton, WA
clock fuse is randomly blowing

title pretty much says it..

this problem just started on friday. i opened my door, the fuse pops. takes out the clock, stereo, dome light, and reading lights.

at first i thought it was the dome light bulb becasue the metal cover was loos off of the glass. so i got a new led bulb (it changed colors on its own.) could it be pulling more than 15amps? highly doubt it.

if i open just my drivers door. it will be fine. if i have both doors open, the fuse blows.
on the way home. the fuse blew again when i opened just my drivers door, no dome lights, reading lights, stereo or clock. so i staretd my truck and drive home.

while on my drive home, my clock started flickering and kinda stayed on but very dim...and while the clock was doing this, i opened my door to see if the dome light would work, no luck. but it turned the clock off. as soon as i closed my door, the clock came back on...then i tried the reading lights. and the same thing happened. clock went blank... so i checked voltage at my dome light. there is 2.93volts. with the fuse blown!. my question is. do you think it is a short to power? or short to ground?

if i were to go replace the fuse right now without doing anything, everything would work as normal, but who knows how long it will last.. lol. so its random. but what do you guys think!?

im gna track down a wiring diagram and start checking wires, to see if i can isolate the problem..
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Old Nov 29, 2009 | 05:55 AM
  #2  
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If it mainly happens with your doors opening it sounds like there is a short somewhere on the door pin trigger wire circuit.
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Old Nov 29, 2009 | 09:41 AM
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A fuse won't blow "randomly". There has to be a short in the wiring that sends the current direct to ground. A chafed wire can intermittently bump up to a grounded piece of metal due to bumps or even how the vehicle is loaded and blow the fuse "randomly". This makes it really hard to troubleshoot. You may have to inspect each wire in the circuit and shake the harnesses to get it to blow while you're looking. You can run new wiring to the systems on the circuit, which is sometimes easier than locating a short in a wire.

Don't bypass the fuse or put a bigger fuse in! The fuse protects the wiring from overload and hence a fire.

These things are difficult to find and can take some time so patience is the key.
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Old Nov 29, 2009 | 10:05 AM
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I had a similiar issue with my dome light. I had to completely trace the wires to find the short. It was exactly what bugs1961 said - a chafed wire would intermittently ground itself causing the fuse to blow. This was especially the case when it was humid or raining out.

Good luck.. at least you shouldn't have to go too far since the clock wiring is inside the dash.. it will probably be a bitch though since the wiring is probably part of a larger loom..
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Old Nov 29, 2009 | 04:12 PM
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From: Renton, WA
IM STILL A LITTLE CONFUSED. (WIRING ALWAYS HAS DONE THAT TO ME.)

RG HAS 12VOLTS WITH THE KEY ON AND FUSE IN PLACE.
RG ALSO HAS 12VOLTS WITH THE FUSE REMOVED.
BW(MINE IS RW) HAS 12VOLTS WITH FUSE IN PLACE AND 0V WITH FUSE MISSING.
G WIRE IS MELTED AND BURNT. (THIS ONLY HAS POWER WITH LIGHTS ON, THE FUSE BLOWS EVEN WITHOUT THE LIGHTS BEING ON.)

I DONT SEE HOW ALL OF THESE ITEMS ARE CONNECTED BY THIS FUSE THOUGH.
THE READING LIGHTS, DOME LIGHT, BUZZER, CLOCK, STEREO SYSTEM.

I DONT HAVE A CIG LIGHTER OR POWER ANTENNA ANYMORE.



SEE THE CLOCK PICTURE.


ANYONE CARE TO JOIN IN AND HELP? MAYBE GIVE ME A DIRECTION TO GO TOWARDS. ANY HELP WOULD BE AWESOME. THANX.!
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Old Nov 29, 2009 | 04:38 PM
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You have a short 100% guaranteed...., just start tracing wires that connect to that fuse.
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Old Nov 29, 2009 | 05:06 PM
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From: Renton, WA
yes. i have a short. i just cant find it. lol.. i have the whole dash out of my truck,. and the harness about halfway out of the truck. ahhhhh

but if i were to go plug a fuse in. everything would work normally. so thats why im a little confused.!?
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Old Nov 29, 2009 | 05:29 PM
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From: Spokane, WA
o.0
interesting.
unplug the clock and see if it still happens..
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Old Nov 29, 2009 | 06:23 PM
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From: Anchorage
The clock gets power from 3 different fuses: cig--turns the clock display on with the key in the Acc or On positions; tail--dims the clock display when the head/tail lights are turned on; dome--provides continuous power to the clock to maintain the current time with the key off.

From what you describe, the TAIL fuse is the one blowing, even with the head light switch off. My '89 wiring diagram shows a TAIL relay that operates when the light switch is turned on. With the switch off, there should be no power to the TAIL fuse unless the relay has an internal short. Try replacing the TAIL relay with a similar one in the relay box and see if the fuse still blows.

You may have 2 problems: a short in the clock (since the wire is burned) and a bad relay (since the fuse blows with the headlight switch off).

If all else fails:
The wire from the fuse that blows is the one with the short. Use your wire diagram to determine which wire is on that fuse and chase it back to the fuse. A short on a different wire from the same fuse could also cause the clock to flicker and dim as power surges on the whole circuit. You may have to chase each wire on the fuse circuit individually to find the short. It may not be under the dash but could be anywhere in anyone of the wires.
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Old Nov 29, 2009 | 07:57 PM
  #10  
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From: Renton, WA
Originally Posted by bugs1961
The clock gets power from 3 different fuses: cig--turns the clock display on with the key in the Acc or On positions; tail--dims the clock display when the head/tail lights are turned on; dome--provides continuous power to the clock to maintain the current time with the key off.

From what you describe, the TAIL fuse is the one blowing, even with the head light switch off. My '89 wiring diagram shows a TAIL relay that operates when the light switch is turned on. With the switch off, there should be no power to the TAIL fuse unless the relay has an internal short. Try replacing the TAIL relay with a similar one in the relay box and see if the fuse still blows.

You may have 2 problems: a short in the clock (since the wire is burned) and a bad relay (since the fuse blows with the headlight switch off).

If all else fails:
The wire from the fuse that blows is the one with the short. Use your wire diagram to determine which wire is on that fuse and chase it back to the fuse. A short on a different wire from the same fuse could also cause the clock to flicker and dim as power surges on the whole circuit. You may have to chase each wire on the fuse circuit individually to find the short. It may not be under the dash but could be anywhere in anyone of the wires.

thanx for your help man.

i dont think its the tail fuse. as i still have tail lights, headlights, brake lights. cluster lights. etc. maybe.. im not sure.. i do not have a cover for my fuses.

its the fuse thats missing in the picture that keeps blowing...

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Old Nov 29, 2009 | 07:59 PM
  #11  
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From: Spokane, WA
why don't you have two fuses in the open slots on the right?
my pickup has those..
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Old Nov 29, 2009 | 08:02 PM
  #12  
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From: Renton, WA
u mean on the left??

those are to hold spare fuses i believe... someone correct me if im wrong.
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Old Nov 29, 2009 | 08:27 PM
  #13  
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From: Spokane, WA
>.>
that would explain why they werent listed on the littl paper thingy..
d'oh.
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Old Nov 30, 2009 | 07:58 PM
  #14  
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From: Renton, WA
i found the short!!! after i tore my whole dash apart.. i traced the wire down and found that the power wire for all of the lights in that circuit was bare and grounding out/shorting on the inside of passenger door!!
ahhhhh!

oh well, now the dash is out. time to paint it.!
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