Intermittent Turn Blinkers & Hazards

[Scott z]

2003 A1

I’m stumped. Some days they work, some
Days they don’t.

I’ve replaced relays.

Any thoughts?

 

[Ronmar]

When the TS don't work, does the hazard switch turn on flashers?

 

[Scott z]

When the TS don't work, does the hazard switch turn on flashers?

Nope. They are clearly both failing together. If they aren’t working I’ll usually put the hazards on so if they start working I’ll see the hazard flashing on screen.

 

[GeneralDisorder]

How many of the ~100 grounds have you cleaned so far?

There's at least one or two behind each turn/park housing and some are nearby on marker lights, headlights, or inside the driver's side step with the washer bottle.....

Also could be the flasher module or the column switch.

Clean ALL your grounds. Look at ALL he wiring behind and nearby all of the turn/park housings. Make sure PVT Snuffy didn't wire them wrong. Also some of the older LED versions will just fail and do weird stuff like flash once or twice and then fade out..... lots of possibilities actually. Have to just start checking stuff. Grounds first IMO.

 

[Scott z]

How many of the ~100 grounds have you cleaned so far?

There's at least one or two behind each turn/park housing and some are nearby on marker lights, headlights, or inside the driver's side step with the washer bottle.....

Also could be the flasher module or the column switch.

Clean ALL your grounds. Look at ALL he wiring behind and nearby all of the turn/park housings. Make sure PVT Snuffy didn't wire them wrong. Also some of the older LED versions will just fail and do weird stuff like flash once or twice and then fade out..... lots of possibilities actually. Have to just start checking stuff. Grounds first IMO.

Thanks. I have not gone hunting for poor grounds. I’ll gice that a try.

 

[GeneralDisorder]

Thanks. I have not gone hunting for poor grounds. I’ll gice that a try.

Then you have a significant chance of encountering more electrical problems as you continue to own the truck. The first thing every owner of these trucks should do is clean EVERY ground connection on the truck. Some, like the main cab ground strap, should just be replaced with one that is easier to access (leave the stock one alone - it's very, very difficult to access the frame side). And also the battery terminals, alternator terminals, LBCD terminals, starter and aux solenoid terminals, ether solenoid and grid heater terminals...... there is probably several days, and easily 100+ connections that should be addressed on these trucks before you can consider the electrical system reasonably maintained.

 

[MatthewWBailey]

Then you have a significant chance of encountering more electrical problems as you continue to own the truck. The first thing every owner of these trucks should do is clean EVERY ground connection on the truck. Some, like the main cab ground strap, should just be replaced with one that is easier to access (leave the stock one alone - it's very, very difficult to access the frame side). And also the battery terminals, alternator terminals, LBCD terminals, starter and aux solenoid terminals, ether solenoid and grid heater terminals...... there is probably several days, and easily 100+ connections that should be addressed on these trucks before you can consider the electrical system reasonably maintained.

A0 Alternator excite wire question- Get Well grounded

now that it is warm... my alternator occasional works LOL. (200 amp Hummer) Will the excite wire get voltage if the alternator ground is not at all or is poorly connected? Knowing that will help me diagnose if it is that or ground (or regulator)

www.steelsoldiers.com

 

[Ronmar]

Ok, as mentioned, grounding, or light sw, or flasher unit, or TS switch on the column Or hazard sw in the dash as it provides all power to the flasher…

next time it happens note if relay K9 is energized or de-energized. It gets its power from the light switch via CB74 and it provides the power from CB71 to the flasher to energize it. If it has de-energized, the issue is the source power from the light sw.

since the flasher output goes thru many different contacts on the TS switch, i don’t see the problem in the switch itself, especially one that comes and goes. the most likley culprit there would be an issue on the switch connector IMO.

other than a bad ground, it could be a loose connection on the hazard sw, or the flasher itself is randomly failing. You would have to probe the in and out wires on its connector, B is power in, A is flash pulse out and C is connection to ground…

Mmmm Intermittent problem, Mmmm

 

[Scott z]

Ok, as mentioned, grounding, or light sw, or flasher unit, or TS switch on the column Or hazard sw in the dash as it provides all power to the flasher…

next time it happens note if relay K9 is energized or de-energized. It gets its power from the light switch via CB74 and it provides the power from CB71 to the flasher to energize it. If it has de-energized, the issue is the source power from the light sw.

since the flasher output goes thru many different contacts on the TS switch, i don’t see the problem in the switch itself, especially one that comes and goes. the most likley culprit there would be an issue on the switch connector IMO.

other than a bad ground, it could be a loose connection on the hazard sw, or the flasher itself is randomly failing. You would have to probe the in and out wires on its connector, B is power in, A is flash pulse out and C is connection to ground…

Mmmm Intermittent problem, Mmmm

Ypu might hate this reply for it’s noob lack of specificity but during initial trouble shooting “the” relays related to the hazards were blinking green during each attempted hazard flash. So it seemed I was getting power there.
I replaced those relays and the green “relay” lights still blink.

A loose ground would certainly match the intermittent part of this.

 

[Ronmar]

You might think it a noob clue, but there is no such thing. Observation is observation…

Ok, the only relay indicators that would flash with Hazard or turn are the trailer light relays that switch 24v to power commercial 24v trailer lighting, K30 and K31.

You say the green LEDs flash but does the relay click when the led is flashing? Do they click when the TS are not working.

And what should have also been one of my first questions, do the brake lights work when the TS/flashers fail?

What do those relays(K30-31) do when you step on the brakes(must have air in the system to activate the brake light switches)? Which is why it should have been one of my first questions, the brake and TS share >90% of the same circuitry…

Does the brake pedal cause the same K30-31 relay response when the flashers are not working?

if only the LEDs are coming on, but no relay clicking, the flasher could be having trouble delivering current. If brake pedal application while this is happening causes the same result, you have a bad connection somewhere limiting current flow. But if brake pedal application pulls in the relays and activates the brake/TS lights, then the circuitry is mostly OK and the issue lies towards the flasher(bad flasher, bad connection) that cannot deliver enough current to pull in relays and light the bulbs when flashing, but the little green LEDs require almost no current to illuminate…

Your noob observation may have localized your issue…

i did this drawing for an A0, but the A1 is mostly the same. The only real difference is the A1 provides voltage to the brake relay thru the pedal switches, the A0 provides a path to ground thru the oedal sw to energize the brake relay. The TS/flasher circuitry is the same…

 

[Scott z]

You might think it a noob clue, but there is no such thing. Observation is observation…

Ok, the only relay indicators that would flash with Hazard or turn are the trailer light relays that switch 24v to power commercial 24v trailer lighting, K30 and K31.

You say the green LEDs flash but does the relay click when the led is flashing? Do they click when the TS are not working.

And what should have also been one of my first questions, do the brake lights work when the TS/flashers fail?

What do those relays(K30-31) do when you step on the brakes(must have air in the system to activate the brake light switches)? Which is why it should have been one of my first questions, the brake and TS share >90% of the same circuitry…

Does the brake pedal cause the same K30-31 relay response when the flashers are not working?

if only the LEDs are coming on, but no relay clicking, the flasher could be having trouble delivering current. If brake pedal application while this is happening causes the same result, you have a bad connection somewhere limiting current flow. But if brake pedal application pulls in the relays and activates the brake/TS lights, then the circuitry is mostly OK and the issue lies towards the flasher(bad flasher, bad connection) that cannot deliver enough current to pull in relays and light the bulbs when flashing, but the little green LEDs require almost no current to illuminate…

Your noob observation may have localized your issue…

i did this drawing for an A0, but the A1 is mostly the same. The only real difference is the A1 provides voltage to the brake relay thru the pedal switches, the A0 provides a path to ground thru the oedal sw to energize the brake relay. The TS/flasher circuitry is the same…


View attachment 928670

Thanks a million. I’m away from the truck today but can start trouble shooting tomorrow.
First thing will be to confirm brake lights.