Need auto electric help, Chevy truck:

[speeder]

Before I leave this thing in a shop, thought I'd do some internet wrenching here. 1988 Chevy K1500, (1/2 ton 4WD), first year of then new body style. Turn signals not working, nor are reverse lights. (They are on the same circuit).

-Fuse is good and has power to it.
-Flasher relay is good/new.
-Electrical part of switch is new, (behind steering wheel).

My auto electric skilz are weak, obviously I have been throwing parts at it. Still, I've spent less than what a 1/2 hour at a shop would cost. Other than checking for power at different points, I have not much game.

Anyone familiar with this beast or just have general experience? I just got my Chilton's manual in the mail and GD if it doesn't have a word about turn sigs in it. I kid you not...every other component from the cig lighter to the lug nutz and nothing on the signals.

Oh yeah, 4-way flashers work fine. This is driving me nutz.

[Laneco]

Does this have tilt? I've heard about the portion of the harness that goes through the column being damaged by using the tilt (repeatedly through the years).

Take that suggestion with a grain of salt - it was just something someone told me one that that stuck in my head.

angela

[RANDY P]

fiddle with that plug at the base of the steering column that goes to the backup switch assy. I've seen that switch there do weird **** in the past. No lights on dash but truck runs? I'd also check every single other electrical function on that truck to ensure there isn't something else that isn't powering up-

Rationale- flaky ignition switch...

[porsche4life]

I think Angela is on the right track. Time to start chasing the wires from the switch to the flasher and beyond. Go over the insulation, undo connections checking for corso on and clean as needed. We fought shift issues on a truck for a long time until we found some mouse chewed wires way under the dash....

[LeeH]

Are the brake lights working? Emergency flashers? Headlights? Tail lights? Does it have wiring for a trailer? Factory or aftermarket?

If everything else is working, I'm leaning toward a ground issue on that circuit.

[RANDY P]

#1 I've had blow up on me..

[speeder]

Thanks you guys. I'm going to do into the steering column tomorrow, pretty sure it's in there somewhere. The reverse light switch is highly suspect since they're on the same circuit.

[Jim Richards]

This may not apply to your particular electrical issue, but I generally check to make sure my ground connections are good. I hope you are successful fixing this.

[Rick V]

The turn signal circuit runs through the brake light switch.

[john70t]

(Just a thought)
Briefly looking at http://ww2.justanswer.com/uploads/RoadsideJerry/2010-05-26_223414_speedo_1.png:

At the top left side of section [D], the 'dir flasher' feeds a common (+) dark blue wire to both the turn and backup switch circuits.

The open might be inside the flasher, the blue wire, or the connector where the two circuits split off.

[john70t]

Back-probe the connectors safely using a thin needle on an alligator clip.

[speeder]

Ok, I have power to the back-up switch, (blue wire), should it pass through to other plug on sw?

[john70t]

Try: Parking brake on/Key-On Engine-Off/Put it in reverse gear.
Does voltage change after the switch with this?
If so, everything up to the switch should be good so continue downstream.

Also jump across the switch to notice change.
It could be an 'always open', or an 'always closed' switch.

Interesting puzzle.
I first thought the light box assembly might have a single bad common ground, but the flashers work.

[jwgn777]

[COLOR="Purple"] Did you install the signal switch behind the wheel in the column housing your self? How did you know it needed that switch? Do you have the old switch? disconnect the plug connector and plug the old switch in and with your hand click the signal to see if it works or if you have the same problem.. I do this with a known good switch to see if the existing switch is defective./COLOR]

[speeder]

Jwgn, that's what I should have done but no, I just changed it. As of right now, I have a known good turn sw, flasher unit and reverse light sw + working brake light sw. Still no turn signals. Power to the fuse and flasher, good fuse.

[speeder]

OK, absolutely everything works except the turn signals. No power to the switch.

[jwgn777]

OK so when you put the signals on you can hear or can't hear the flasher working but still no lights? And there are no signals in the front and rear. Does that vehicle have a fuse and relay distribution box under the hood?

[speeder]

jwgn, sorry, I was banned for a minute there. There is no flasher sound, no lights, nothing. There is power going to the brake light sw but none coming out the other wire, (that goes to turn signal sw). The turn sw must not be grounded, I have a strong suspicion that it has to do with the ignition sw.

The PO, (a real greased donkey when it comes to wielding tools), said something about the turn sigs stopped working when he replaced the ignition lock cylinder. I assumed, (incorrectly), that he simply man handled the electrical sw behind the steering wheel and broke a wire/connection or something. It appears to be something more sinister. He broke some ground(?) between ignition sw and turn sigs, I think.

When it comes to auto electrics, a famous quote from Steven Seagal always comes to mind:

"Assumption is the mother of all fk-ups."

[diverdan]

Additionally, I believe that there are two fuses. One is on the side of the dash and the other is under the hood. In addition, the taillight assemblies have a tendency to malfunction and may need replacing.. Another area of contention may be in the trailer wiring. I've had the similar problems with my K3500 1996. However, its got less than 300k miles. Good luck.