Turn signal trouble shoot (1 Viewer)

[thebigredrocker]

Re: testing the right side turn signal/markers. If you have gator clips you can clip it to the front mounting bolt and then to bare metal(preferably frame). Or just wrap some wire around the bolt and a ground location, your close enough to battery negative you could just stuff a wire in the battery post clamp.

Don't forget to eventually clean some bolts that fasten the front fenders to the frame. Might not hurt to chase threads of the dedicated fender nuts welded to frame.

Some of my grounds may be overkill, here's a front fender to frame ground on my 76

Rear frame to tub ground(need to move the bolt)

 

[Cleg]

It helps to eliminate any question about grounding.
You can make a clip lead about 8' long to clip to the negative side of the battery that can reach anywhere on the truck.
If you are doing a lot of wiring, it saves time over looking for a good ground in the vicinity of each lamp.

 

[Coolerman]

thebigredrocker, those are excellent grounds! You even covered the bolt head with something to keep it from oxidizing!

Cleg, A set of cheap jumpers cable and a smaller clip lead let me do the same thing: reach any point of the truck with a good ground straight from the negative battery terminal.

 

[ollanik]

OK - another mystery but maybe easier to solve....
I used a 12v simple circuit tester to go between fusible link and battery after removing positive battery cable and the tester lit up indicating a circuit and a short(I presume). Proceeded to test each fuse and light did not go out. Then pulled all fuses and light did not go out......... what is left?

 

[ollanik]

Ok - trying to track down my short I used my circuit tester by disconnecting the battery cable and hooked up the clip to the wire going to my fusible link. When I touch the tester to the positive pole on the battery I get the light on indicating a complete circuit and the presence of a ground or short in my wiring.correct?
I then removed fuses one by one to identify wher short was but light never went off. I then removed all fuses and light still is on.

I'm stumped....what to check next.

 

[ollanik]

Not sure why both posted.....sorry.

 

[thebigredrocker]

What's got you thinking you have a short?

 

[ollanik]

Low voltage at lights and flashers not working properly....as noted earlier in thread.

 

[ollanik]

I assume the low voltage can also be a line loss issue due to improper grounding along the way....

 

[thebigredrocker]

Coolerman's explanation was exactly what happened on both my cruisers.
When he says "If any, all, or some of the above apply...Your turn signals will NOT flash!" That is the gospel, in my experience. Keyword=any. SO, if you have ONE bad ground, goofy stuff will happen with your flashers.

I assume you've pulled all four turn signals and cleaned the ground paths(ground flows through the mounting bolt to the nut/washer and then metal they are bolted to). I also assume you've cleaned the female + terminals(micro round file works good) on the harness and the turn signal bullets. Remember, your front fenders need a bare metal ground path to the frame. Also, make sure you cleaned the 4 pin rear harness connector I posted a picture of.

The only things I can think of that hasn't been mentioned is:

1. make sure you battery - cable isn't internally corroded(I've seen corrosion creep 18" inside a cable) & especially make certain that it has clean bare metal contact at the frame.

2. With battery disconnected, pull your fuse panel and lightly sand every bit of metal, bend the fuse tabs so they grip the fuses tightly. Sand/scuff the harness connectors that plug into the panel.

I think the fuse panel also needs a clean bare metal ground to the firewall. I would run a tap through both welded nuts that secure the fuse panel to the firewall @Coolerman would know if that's important.

3. make sure your tub is grounded to the frame in a few spots. Hidden ground straps work good IMO.


Take your time, enjoy and be THOROUGH!

 

[ollanik]

Awesome! Thanks big red

 

[adistler1]

This has happened to me twice and I replaced my turn signal relay. It fixed it for me both times.

 

[ollanik]

When I painted the beast I never re-established the ground from the fender to the frame....that is my next spot and then some strategically located grounding straps....I used them extensively on my old Willys military jeep.

 

[thebigredrocker]

This is unrelated to your turn signal issue, but I figured I'd mention it in while we're on the subject of grounds. You probably know this. Many of the dash switches rely on bare metal contact with the backside of the dash. I recently was having an issue with my wiper switch not squirting washer fluid when I twisted the knob. After discovering I had power to the washer motor, I attached a grounded gator clip to the wiper switch...BINGO!

 

[Coolerman]

As far as I know, of all the dash switches in an FJ40, only the wiper switch requires grounding and as you stated it is only for the washer motor to function. The fuse panel does not require any ground, nor does the flasher unit.

The reason your test light stayed lit even after removing fuses is because it was feeding back through the alternator.

Tip: A true SHORT will cause fuses to blow (if you're lucky) or wires to melt and let out the magic smoke if you're not.

To check for bad grounds you need to either measure voltage drop across a harness section or use a very sensitive ohm meter to measure actual circuit resistance. Most cheap meters cannot reliably measure below a couple of ohms. The meter also needs the ability to zero out the lead resistance when doing low ohms work. If you set your meter to low ohms and short the two meter leads together you will get a reading of the resistance of the meter leads themselves. Better meters have a button that allows one to subtract this reading so that what you read is the actual circuit resistance, not the circuit resistance plus the lead resistance. I find it much easier to measure voltage drop to find bad connections as even cheap meters will do that to a tenth of a volt.
Tip: Always use the SAME grounding point when measuring multiple voltages. I always use the negative battery terminal when possible. If you use different grounding points you won't know if a bad ground is skewing your results. Start by measuring the battery voltage directly at the battery. Write this reading down. Now take a reading somewhere else, say at the fuse block where the White/blue wire attaches, but leave your black lead on the battery negative post. This reading will be a bit lower due to wiring resistance and interconnection resistance.

To give an example more suited to your issue: Measure voltage at the battery, then go to the passenger side front turn signal and measure at the bulb contact with the turn signal on. The difference between these two readings will tell you how bad the circuit is between the battery and the bulb socket. A difference of a volt or so is normal but a two volt drop or more says something is really not right. You will never achieve +12V at the lights with the methods that were used to wire an FJ40. You could clean every single connection until it shone like a mirror and still lose a volt. This has more to do with wire size and the fact that the wire oxidizes inside the insulation something you can't fix.

Try swapping the bulbs from the left side to the right side. If it now flashes on the right you may have a bulb that is the wrong type.

Mark aka Coolerman