‘77 280z signal fuse keeps blowing up

[240zadmire]

I cleaned the multi-switch 3 times.  Perhaps the 4th time will do the trick? 😉

 

[Dave WM]

1 hour ago, 240zadmire said:

I cleaned the multi-switch 3 times.  Perhaps the 4th time will do the trick? 😉

 

You have to be very careful about all the little plastic bushings/washer placement. I goofed on and ended up blowing fuses when activating the washer button

[dutchzcarguy]

On 7/22/2022 at 2:24 AM, 240zadmire said:

will check again tonight to see what wrong.

 

stay tune.  Live and learn new thing everyday

 

Hihi.. don't.. please don't be angry with me but i'm here also to learn a bit of extra english.. (So correct me if i'm wrong but i wanted to "learn" you some hahaha)

I think It's:

to see what'S wrong and.. stay tuneD. Live and learn new thingS every day.   (Hihihi.. i'm sorry for correcting already or is english not your first language?)

ABOUT the fuses..

Zedhead is right.. and.. also,

It could be a lose wire or one that's been damaged and sometimes makes a short to the frame.  I've seen flashers that were rotten away on the inside and they blow fuses to.  Most times you will find the problem near the flashers and other parts were there are connectors. Last place to look is the cables lying in the car on the floor and through the firewall, check your rubber grommets.

Hope you find it soon because there is no problem in electronics worse then have a problem sometimes! (intermittent) One can take out a multimeter and measure but most of the time all is well and that's bloody frustrating, as an ex elec. engineer i know all about that!

Edited August 9, 2022 by dutchzcarguy

[240zadmire]

@dutchzcarguy apologies for rudimentary gramma mistakes.  I understand it is irritating and sometime annoying to read such poor gramma.  Worst, an incorrect place of apostrophe or comma, could have a different meaning altogether…. I will do a better job before submitting.

 

There seems to be 2 flashers mounted under the pedals box.  One is longer, bigger and I think it’s dead.  The previous owner didn’t pull it off.  The working one is smaller but is making a really low sound when turn signals or hazard switch is engaged.  I believe I read on some other threads that it is normal, though it would be better if the sound is louder.  However, that is for some other day.

Yeah, the intermittent blown fuse is frustrating, indeed.  My recollection is that it’s blown during the hot days.  I like @Zed Headtheory.  I’ll follow that path to see where it leads.

 

stay tuned and stay indoor with A/C or shaded area. It’s sizzling in the south land!

[Jeff Berk]

Might be a job for a "Fuse Buddy". I'm not sure if they make one that will connect with a glass tube fuse. This would tell you the draw on the circuit so you can tell if you are always very close to the 10 amps or if certain conditions trigger the over amp condition.

I was having similar issues shortly after purchasing my car. For a while I had so many fuses blown on one of my circuits that I replaced the glass fuse with a breaker. If I recall correctly, I changed all my bulbs to LEDs and installed turn signal relays to lessen the amp load and that fixed (or hid) the issue. 

I had also rewrapped most of my wiring harnesses and discovered in the process several damaged wires and many ground wires from different components connected to a single ground wire. This was concerning because the single wire might not be able to handle the load from this old car. The circuits in your car has more resistance than when it was new. That turn signal stalk likely is a point of high resistance from close to 50 years of arcing and it may be time to flip the contacts over to a clean side. The wiring harness connectors are also likely in need of cleaning.

Electrical issues are not fun to track down but a part of owning a classic.

Edited August 10, 2022 by Jeff Berk

[Jeff Berk]

10 hours ago, 240zadmire said:

There seems to be 2 flashers mounted under the pedals box.  One is longer, bigger and I think it’s dead.  The previous owner didn’t pull it off.  

On my 260z there are also two flasher relays.

Hazard relay: black with yellow wire and a green with white wire

Turn signal relay: white wire and green wire. 

[dutchzcarguy]

5 hours ago, Jeff Berk said:

On my 260z there are also two flasher relays.

Yup.. That's normal..  if you ask yourself why, the total power needed for indicating direction is lower than for the (all flashers flashing) hazard.. this makes that you need 2 different flasher relais.

Did you know the power of those is different for a US or EU model flasher?

Overhere it's (i believe) 2x21 Watt + 2x5 watt  (Total=52 Watt)

and for the  Hazard it's 4 (!) x 21 Watt + 2x 5 Watt.. (Total=94 Watt)

This apply's ofcourse only for the older cars.. todays cars have other systems i think?  (Don't want to work on those!)

 

16 hours ago, 240zadmire said:

apologies for rudimentary gramma mistakes.

You don't have to apologies yourself!  It's not annoying or so..  Just thanks for trying to do a better job!

 

6 hours ago, Jeff Berk said:

I'm not sure if they make one that will connect with a glass tube fuse

I remember that i ones made a big glas fuse that was blown into a auto fuse by soldering a auto fuse over it, i still have it in my 240z glovebox.. not needed it for a very long time now..

(Btw.. Jeff, i couldn't find a single mistake in your Grammar!  😄)

[Jeff Berk]

5 hours ago, dutchzcarguy said:

(Btw.. Jeff, i couldn't find a single mistake in your Grammar!  😄)

Have you noticed that most of my quotes show I edited them shortly after I posted them?

[240zadmire]

The fuses box look cleaned to me.  No obvious rust or corrosion that I can see. 
 

I tried to repeat the steps that cause the fuse blown last time and noticed some interesting behavior.

when the engine first started, I turn on A/C to maximum airflow but the A/C’s compressor clutch disengaged at maximum.  Turn signals were working fine though.  Reduce the airflow one click and the A/C’s compressor clutch engaged again.   Seem like every level of airflow, the clutch engaged just fine except the maximum.  This is only happen when the engine first started.
 

The different is the car was in garage. So the ambience temperature is much cooler vs when the fuse blown, the car has been cooked under the sun couple of hours already.

 

[240zadmire]

Car has been cooked the whole day under the sun.  
Switch on AC to max and tried the switch on the signal immediately… poof there goes the fuse.  Touch the AC and fuel gauge fuse terminals and really hot to the touch.  All other fuses are cold.  What does that tell you?

Edited August 11, 2022 by 240zadmire

[dutchzcarguy]

19 hours ago, Jeff Berk said:

most of my quotes show I edited them

I often do that to.. read what i wrote and correct..hihi..

On topic..

When you start up the car for the first time.. and go max in the aircon it's totally possible (i think) that there is a moment that the compressor switches off because the system freezes up! (Inside the car)

To find the problem in your electronics you need a amp.meter (Ampère) and some luck and a lot of patience 🙂 ,,,

When you can't find the culprit, you should switch off/take out parts of the circuit and look if the fuse still blows.. if so , the problem is still in the car.

(Did you guys know that i did this sort of trouble shooting (in securitysystems) was my job for over 10 years hihi..)

Btw, with taking out i mean of course switching/disconnect it.. not literally take all out.. 😁

(Hey Jeff, i just found out... "of course" are 2 words not one!  😉 )

[240zadmire]

Purely trials and errors ...

Without turning A/C, drove the car to work.   A good 45 minutes arrived at work.  Check all the fuses by hand touch and they are as cool as cucumbers.  While the car is in idle, turn on A/C for a couple of minutes, the fuel gauge and A/C fuses start warming up.  There is something going on there.  Time to spend some quality time with the wire diagram.