84 K10 Lighting problem, this is weird

[MountainGoat1966]

I did the search thing and all I found was advice to check ground connections.
Well, I did that and verified all bulbs and connections.
Here is my 84 K10 lighting issue, turn on parking lights or headlights, and the left turn dash indicator bulb glows bright. Left turn bulbs won't blink if the turn signal switch is connected.
I disconnected both connectors coming out of the steering column, eliminating the turn signal switch from the circuit, and I still get the left turn indicator glowing when the light switch is pulled out.
I was always taught to test, don't guess, and I can't afford to start replacing parts left and right in hopes of curing the problem.
How or what do I do next? Is it possible I have a bad headlight switch causing the issue ?

[willett]

Grounds is the obvious first thing as you know. How's your under dash ground? (Big spider above e brake cable)

How's your flasher? Those can do weird things sometimes when they go.

Headlight switch shouldn't be more than about $15. Try that if all else fails

[MountainGoat1966]

I had two spare headlight switches on hand, no change.
Also had flashers on hand, no change.
Thanks for the suggestions, though.
If I could get a complete OEM wiring harness for the truck, it would still be cheaper than taking it to a shop and pay a hundred bucks an hour for substandard work.

[MountainGoat1966]

Here is another piece of the puzzle I just discovered, if I remove the bulb from the left front parking light fixture, the issue goes away.
Inserting a known good bulb, the issue returns.
I am thinking of placing the blame on the pass through firewall connector where the wires for the front lights go.

[dman1982]

i had this same issue, it was infact a ground, it was the ground that goes on the fender well on the drivers side, it actually did it twice, the first time it was corroded and the second it came undone, not saying this is your problem but worth double checking

[MountainGoat1966]

I looked for a ground on the driver's side fenderwell but found none.
I see a ground on the passenger side, and what seems to be a ground going into the firewall through connector.

[dman1982]

I may have been wrong, it might be on the d/s core support

[ray_mcavoy]

^ I agree ... this sure sounds like a ground issue to me as well.

There should be 2 ground screws on the core support... one on each side. Start at the headlight connector and follow the wires back if you're having trouble locating one of them.

Since the ground wire on each side is shared by the headlight, parking light, and turn signal, there is still a connection between those lights even if the connection to ground (via the core support) is lost. That allows the head/park light on that side to find an alternative ground path back through the front turn signal circuit, causing the signal indicator on the dash to glow. Removing the bulb from the parking / turn signal socket breaks that alternative ground path.

[dman1982]

Originally Posted by ray_mcavoy

^ I agree ... this sure sounds like a ground issue to me as well.

There should be 2 ground screws on the core support... one on each side. Start at the headlight connector and follow the wires back if you're having trouble locating one of them.

Since the ground wire on each side is shared by the headlight, parking light, and turn signal, there is still a connection between those lights even if the connection to ground (via the core support) is lost. That allows the head/park light to find an alternative ground path back through the front turn signal circuit, causing the signal indicator on the dash to glow. Removing the bulb from the parking / turn signal socket breaks that alternative ground path.

Haha...also agreed!!!

[buddy_1]

I would check to make sure that the bulb is an 1157 ( 2 terminal dots on the end ) first. I have seen people put an 1156 bulb ( 1 dot on the end ) in the socket and cause this problem. When an 1156 bulb is used in a 1157 socket, the single dot touches both teminals in the socket causing the feed back to the IPC indicator light. I also had a bad bulb in an old Nova when I was in high school cause the same thing. The park light element had broken loose on one end, bounced over and stuck to the turn signal element. If the bulb is good and correct check the socket for being shorted internally.

[Chevy3+3]

Originally Posted by buddy_1

I would check to make sure that the bulb is an 1157 ( 2 terminal dots on the end ) first. I have seen people put an 1156 bulb ( 1 dot on the end ) in the socket and cause this problem. When an 1156 bulb is used in a 1157 socket, the single dot touches both teminals in the socket causing the feed back to the IPC indicator light. I also had a bad bulb in an old Nova when I was in high school cause the same thing. The park light element had broken loose on one end, bounced over and stuck to the turn signal element. If the bulb is good and correct check the socket for being shorted internally.

This is good advice to check along with what others have said. I had a weird wiring problem with an 87' I had years ago. The turn signals were making my headlights blink on one side and some other crazy stuff. I found out it was a bad ground on the top of the drivers side radiator support. I regrounded the radiator support and jumped from it to another ground location which was the drivers side fender in my case. The crazy thing was......when the truck was having problems the grounds actually appeared to be good but when I ran extra ground wires and had multiple connection points the problems went away and never returned.

[motornut]

I've seen those headlight ground wires fried.
One reason , boosting from body as a ground, not engine/alt/batt.
Or the engine or other grounds gone .
That little wire becomes the path.
Check for brittle, baked too.
In fact my 78 had someone try to wedge it back in the ground plug.
Only found it by testing.

[hatzie]

I had the core support grounds do just that on a 79.
I was too hard headed to listen to an older friend that told me I had a ground problem. I chased it for at least a week.
GUESS WHAT... That old timer was right.
It was the RH ground set on the core support. The wires looked great. But. The wire was corroded almost off. The green powder went way back into the jacket. The only thing keeping the "wire" on the ring terminals was the strain relief crimp on the jacket.

The other thing that could do this is forcing an 1156 bulb into the 1157 socket...

[cadillac_al]

Sometimes I will run a separate ground wire from a signal light housing to a good ground if I can't find the problem right away.

[MountainGoat1966]

Okay, it looks like I am on to something here.
I grabbed my ohmmeter to test the ground connections from the socket to core support ground, and found a detail I had missed, the passenger side socket has the ground tab in it but the driver's side socket is missing that metal tab.
It's amazing such a tiny item can cause so much grief and headaches.
Gonna look in my spare parts box to see if I have a socket, otherwise will get one from the parts store Tuesday.
I will keep the thread advised if this cures the issue.

[MountainGoat1966]

Problem solved !!!!!!!!!!!!!!
I spent 7 bucks and got a new socket, wired it in, and everything is fine now.
I don't remember ever changing the bulb, so how the grounding tab got broken off and went AWOL is anybody's guess.
This is one for my notebook, always inspect the socket closely to verify it has all its connections. And keep a spare socket in my parts box.
A hearty thank you to everybody who replied and offered help and assistance !!!

[motornut]

Originally Posted by MountainGoat1966

Problem solved !!!!!!!!!!!!!!
I spent 7 bucks and got a new socket, wired it in, and everything is fine now.
I don't remember ever changing the bulb, so how the grounding tab got broken off and went AWOL is anybody's guess.
This is one for my notebook, always inspect the socket closely to verify it has all its connections. And keep a spare socket in my parts box.
A hearty thank you to everybody who replied and offered help and assistance !!!

up here those tabs rust off

[MountainGoat1966]

Originally Posted by motornut

up here those tabs rust off

This is Arizona, we don't know what rust is, but at least our paint fades fast from the sun.

[hatzie]

Originally Posted by motornut

up here those tabs rust off

I dip these bayonet & T15 bulbs in Vaseline or Silglyde. It keeps the sockets and bulbs A-OK.