As well as many other states across the country, Colorado got hammered with Snow and cold brrrr.. earlier this week (for us unusually cold).

After a few hours of Playing in the snow carting the girls around 2 separate trips to school and to work in the morning. I noticed that when it turned on the left turn signal the light was very dim and it was pulling a big load on the entire electrical system.

After a little bit .. all the flashers stopped working all together. No left, right, or hazards...

Got back to the shop and found the Hazard/Horn fuse blown (under the hood on the passenger side fuse box 15A). And the Turn signal fuse was blown as well (in the cabin on the driver side fuse box 15A).

I replaced both fuses, and tried it again the rear turn signal was very dim but was working. Still creating a very high load on the whole system.

After checking the flasher (under the privacy pannel on the drivers side, bear to get to.. unless you pull the heater ducts too. ) and verifying that it was good..

I set the truck out in the sun the rear end facing the sun... (you would not believe how much snow and sludge fell out of the wheel wells and rear bumper... those 30" tires kick up a lot of stuff) Every thing works fine..

I now know I have a short to ground somewhere in the back ... and its not a full short or it would blow the fuses immediately... This weekend it is suppost to be nice ... maybe 60 Deg F... so I will take a better look at it and see if I can find any thing... I know there was a trailer hook up under there 4 pin ... but its gone now. Who knows what the PO had or did do to the elect system back there ...

But I did take apart the left tail light assembly and there is some corrosion on the sockets ... May have to replace those too... and rewire back there cause the back up light wire on that side is busted on the chassis side of the plug..

If you have any suggestions on where to start .. or if you have seen this .. let me know... I would prefer not to spend my whole Sunday (only day off) tracking down a short or wire in the bundle of wires back there.....

Not only that I still have to figure out why I'm only getting 10 to 13 miles per gal...

Sorry bout the long post..

1991 EXT Cab PU 4X4 5 Speed 3.slow

 

Okay, any short is a short, period, there's no such thing as a partial short, an intermittent short or a short with a dirty connection similar to a bad ground, sure, but it's still a short.

Causes of dimness:

Voltage is too low: A short to ground would make voltage 0, and the light shouldn't come on, if there's a short to ground and voltage is not 0, there's something else majorly wrong. A bad ground can cause this too as it would have a high impedance and that would cause a large voltage drop.

Current is too low: This can be caused by a short to ground that is incapable of supporting enough current to make the extra load pop the fuse immediately while still adding a lot of additional load on the electrical system. It can also be caused by a bad ground, which for much the same reason would be incapable of supporting enough current to keep the light bright.

What I think is wrong is that you have a corrosion/wear problem, and that it's a combination of a dirty short and a bad ground.

 

Don't know how much help this is but I just dealt with a similar problem. Although if I hit the blinker and brakes at the same then everything back there flashed like christmas lights. The corrosion on the sockets of the tail lights is what we think is the problem. We had to file away rust in one spot in order to get polarity between the inside and outside of the socket. I don't understand alot about electricity but my boss was doing all of this and trying to explain it as he went along and said that's my problem. We did get it fixed though so maybe try testing your polarity? I figure if it helped me, it may help you. Good luck

Brad