Author Topic: Turn signals slow to start, Hazards only up front  (Read 1217 times)

Offline srozell

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Turn signals slow to start, Hazards only up front
« on: July 11, 2022, 12:05:39 PM »
I've been chasing this one for days now.

When I first started having problems with this, it was just the turn signals that were slow to start and made no audible click. I would flip the switch, and after a second or two they would start to flash. I replaced the flasher since it was a cheap easy fix, with no noticeable difference.

At that time, the hazards seemed to work well.

Now the front hazards flash at super-speed, and the rears don't flash at all.
The turn signals are still acting up.
Rear driving lights are dim.

I checked for grounding issues. I see I have the fuse box itself grounding at the signals, but no ground between the fuse box and the lights around the truck.
I now have a broken hazard switch (open to recommendations for replacement) which may or may not be compounding the issue.

Alternator is putting out steady power.

I suck at wiring diagrams. What other components could be grounding that could be impacting the lights? Do other systems share circuits in the fuse box?

Are there any other suggestions?
1980 K20 "Camper Special"
1969 K20 Step Side
http://myuglytruck.wordpress.com/

Offline Chevygold

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Re: Turn signals slow to start, Hazards only up front
« Reply #1 on: July 11, 2022, 01:20:09 PM »
Hi a couple of questions before answers, do your stop lights work OK as they are the indicators as well at the rear?
You mention grounds at the fuse box, the fuse box is insulated from ground as all the fuses are in the positive pole.
If the front indicators superflash the rear ones aren't in the circuit.
First place I'd be looking is the turn signal switch as all these circuits pass through it, I lost right rear brake light and indicator and that was where the issue was, if you're lucky you can carefully dismantle it and try cleaning the switch contacts which might cure your problems.

Good luck
Graham

Online bd

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Re: Turn signals slow to start, Hazards only up front
« Reply #2 on: July 11, 2022, 01:36:44 PM »
I checked for grounding issues. I see I have the fuse box itself grounding at the signals, but no ground between the fuse box and the lights around the truck.
I now have a broken hazard switch (open to recommendations for replacement) which may or may not be compounding the issue.

What do you mean by this ^^^^^??  As Chevygold stated, the fuse box should NEVER be grounded!  If the fuse box was grounded then fuses would blow.  On the other hand, every lamp in the vehicle MUST BE grounded in order to function properly.  In other words, every electrical device must have a power in connection (+) from the fuse box and a power out or ground connection (-) to the vehicle frame in order to work.

In what way is the turn signal switch broken?

Your truck has two flashers.  One is used for the turn signals and the other is used for the 4-way hazard lamps.  Which flasher did you replace?  Try replacing the other one with a high-quality electronic flasher. 

Are you using LED turn/marker/tail lamp bulbs?  If you are running LED bulbs, you will need compatible LED flashers.  "Superflashing" generally results from insufficient loading of the flasher, which is a common problem experienced when retrofitting LED bulbs to older vehicles.

For the rear lamps to appear dim, they are receiving low voltage caused by either poor connection(s) in the power feed from the turn signal switch or poor ground connections.  Use a voltmeter to determine which and repair accordingly.
Rich
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In other words... if people learn by making mistakes, by now I should know just about everything!!!
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Offline srozell

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Re: Turn signals slow to start, Hazards only up front
« Reply #3 on: July 11, 2022, 03:11:56 PM »
Hi a couple of questions before answers, do your stop lights work OK as they are the indicators as well at the rear?

Yes, they work fine.

Quote
What do you mean by this ^^^^^??  As Chevygold stated, the fuse box should NEVER be grounded!

That is exactly what I thought, which is why I mentioned it, and am curious of there are other circuits that the fuse box might be connecting up.

What I mean, is if I jam a tester in the fuse box at the signal fuse, and ground the other end, I get current.

I went so far as to pull the fuse box, clean it up, etc. but it was clear the fuse box itself is not directly grounded to the truck.
I also know that the rear lights are not grounded to the truck, as I disconnected the only wire that WAS grounding (left turn signal), and proved that it wasn't grounding when separated from the fuse box.

Quote
Are you using LED turn/marker/tail lamp bulbs?

No. Everything is stock.


I will pull the signal switch and investigate there, and since the 4-way flasher is cheap, I'll replace that anyway. IF the grounding at the fuse box goes away when I disconnect the flasher, I know my culprit.

Thanks for the feedback.

1980 K20 "Camper Special"
1969 K20 Step Side
http://myuglytruck.wordpress.com/

Offline zieg85

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Re: Turn signals slow to start, Hazards only up front
« Reply #4 on: July 11, 2022, 05:57:10 PM »
sometimes an overlooked ground is under the left tail light assy.  You have to remove it to see what I am talking about.  I have a bad ground that would do all kinds of weird things on my 1985
Carl 
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Offline srozell

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Re: Turn signals slow to start, Hazards only up front
« Reply #5 on: July 12, 2022, 01:34:07 PM »
sometimes an overlooked ground is under the left tail light assy.  You have to remove it to see what I am talking about.  I have a bad ground that would do all kinds of weird things on my 1985

Yes, I've had problems there before. I'm not grounded at the rear at all. I complete removed all the wiring in the rear, and repaired some botched "trailer wiring" that was left over from the previous owner. It helped simplify the trouble shooting, and I was able to verify the wiring to the rear of the truck is all good.
1980 K20 "Camper Special"
1969 K20 Step Side
http://myuglytruck.wordpress.com/

Offline Geezer77GMC

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Re: Turn signals slow to start, Hazards only up front
« Reply #6 on: July 12, 2022, 06:26:43 PM »
Both rear lights get their ground from one point behind the left taillight, screwed into the bed sheet metal. The bed must be properly grounded to the truck frame (don't count on the 8 bolts that attach the bed to the frame). The frame needs to be properly connected to the battery negative terminal. There is no factory ground wire that runs thru the harness to the rear lights.