Turn signals and flashers dead - calling all electricians

Sadlsor

Sadlsor

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Joined
Jan 15, 2020
Messages
1,236
Age
69
Location
Birmingham, Alabama
Bike
2008 ST1300A
2008 ST1300, 35k miles.
All signals and 4-way flashers non-blinky, starting about a year ago.
Installed trailer wiring harness AND isolation harness, 3 years back, and it all worked until last year.
All other instruments, headlight, taillight, brake light working and dash lights too.
Warm 'n Safe power and Garmin (through quartet harness) and Powerlet USB port also working.
Horn, hi-lo-beam, ...everything except the turn signals.
I spent time to troubleshoot fuses and relay a year ago, no problem found.
Before I begin the troubleshooting steps in my Honda Service Manual, thought I would disassemble the left switch pod, for corrosion etc.
I think I've given enough information for y'all to theorize, hypothesize, analyze and scrutinize.
First question... IF one of the four bulbs went out, that shouldn't kill them, should it?
Let the games begin.
I'll be checking in regularly with what I find.
Thanks VERY much, in advance.
 
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From Google / AI (this is what I suspected)
"No, one dead turn signal bulb will not kill or stop the other working turn signals on your vehicle.
If all the turn signals on one side or the entire car stop working completely, the issue is rarely a single burnt-out bulb. It is usually caused by a blown fuse, a bad flasher relay, a corroded socket, or a wiring problem."

No visible issues inside the left switch pod, plenty of grease, and no corrosion.
I'll leave the bulbs alone for now.
It's "possible" all four are blown, just highly unlikely.
Moving on...

EDIT: as the bike, with a 1-week old new battery, cranks, runs, and has no other DC gremlins, I will not bother checking Main
Fuse A or Main FUSE B at this time.
 
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Any chance that huge ground connection block near the front of the bike shows signs of corrosion or overheating?

Can you jumper from any of the non-functional item to a known solid ground and test?
 
First check for power on the wire that feeds power TO the turn signal switch.

If none, check for power at each terminal of the turn signal flasher.
 
So here's some insanity for ya... and its outside my own.
(I'll check the 2 suggestions, in a bit.)
Page 22-31, Turn Signal / Hazard Relay, Srep 1 - Inspection, has check battery condition, burned-out bulb, burned fuse, ignition switch and turn signal switch function (FAIL!), loose connector.
As the turn signals still FAIL, it says Replace or repair the faulty parts.
(That's not real helpful...)
Moving to Step 2, which instructs:
Disconnect the turn signal / hazard relay 3P connector from the relay.
Short the Gray and Red/green terminals of the turn signal/ relay connector with a jumper wire. Start the engine and check the turn signal light by turning the switch "ON".
Does the light come on?
YES - faulty turn signal/ hazards relay.
- Poor connection of the connector.
NO - Broken wire harness.

Really?!
That's all you got for me?
Pfffttt.

OK, here's what happened with the wiring harness side, after jumpering the 2 female pins of the turn signal relay, and the engine running:
1. Both FRONT amber turn signals illuminated, solid. No flashing.
2. No turn signals on at rear, both dark / OFF.
3. Switch to left turn signal.
4. Left bulb goes dark / OFF, Right remains solid ON.
5. Both rear signals still dark / OFF.
6. Cancel signal by pressing switch in towards handlebar (as per usual, to cancel signal.
7. Both front turn signals back ON, but solid.
8. Rear turn signals still OFF.
9. Switch to Right turn signal.
10. Right front goes dark, Left remains ON solid.
11. Both rear signals remain OFF.

At this point, I'll check that ground, although in my mind I would think there would be other problems if it was bad or corroded.
(Admittedly, I'm occasionally, or frequently, wrong, depending on the day.)
I am willing to replace that relay, as the not-so-great Service Manual seems to suggest, in my interpretation.
Other ideas still welcome, with this new information.
 
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Larry Fine said:
First check for power on the wire that feeds power TO the turn signal switch.

If none, check for power at each terminal of the turn signal flasher.
Click to expand...
The fact that both front signals are solid ON (not that you knew that, when you posted), that tells me they have power.
The rear signals staying OFF (while brake and tail lights are on and working) is another mystery.
There may be no power there...?
 
One thing not yet mentioned... Last time I was troubleshooting all this, I swapped the Turn Signal / Hazard relay with another relay nearby - don't recall which one - and it didn't work either.
For some reason (likely just ignorance), I convinced myself that meant it wasn't the actual relay.
That is probably pi$$-poor troubleshooting and diagnostics.
Yeah, ignorance.
Works for me, until it doesn't.
 
Kevin_56 said:
Usually it s the last thing we did that is causing the problem. yes 3 years ago you added a trailer isolation system. Yes it "WAS" working, but now nothing is working. Have you removed this trailer system to see if it is causing the issue?
Click to expand...
Wellll... that has been a consideration, here in the second attempt.
You have a good thought there...
The good news is, it will be easy enough to simply disconnect the entire trailer wiring from the battery... so that is worth a try.
 
I would start check starting at the flasher relay first. They aren’t that expensive. The bulb sockets would be next. If you pull the bulbs and corrosion is on the bulb or socket then you may have your answer. The odds that all four bulbs blowing has to be astronomical! While you are checking out all of this, buy you some led replacements for the standard bulbs and a led friendly flasher relay to go with it. The only other thing you mentioned was the wiring harness for the trailer three years ago. I would go over that again and check out the connections there. I feel for you brother, electrical problems are the most madding to solve !!!!!
 
Completely disconnected any semblance of trailer wiring.
It's was SO hard!
Remove the negative trailer lead at the battery, reconnect the main negative terminal.
Ditto for the positive side.
All buttoned up and secured... without the trailer wiring.
Same results.
Both front turn signals on solid, until I signal left or right... the respective signal goes dark, the other stays ON.
Cancel the signal, both on solid. Nothing at the back but the tail and brake lights (when brake applied).
The trailer wiring seems to have no effect on the turn signal issue.
So I'm back to leaning toward the relay as the culprit.
That's it for now, I'll button up both side covers, replace the panniers, and ride to work in the morning... using the old- fashioned "watch me stick my arm out... do you even know what this means?" signals for making a turn.
Thanks for all the input, y'all.
I'll get about ordering a new relay like this one...
 

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Remember that each front signal has running lights that turn off when each side's signal is turned on (for greater contrast). Those are working correctly, and are what you're seeing.

What's still missing is the turn signal. Look for power at one of the flasher socket terminals. One terminal comes directly from its fuse, the other goes directly to the signal switch.

If you don't have power at the flasher, everything else is wasted effort. Buying parts is a terrible method of troubleshooting. The best electrical troubleshooting tool is a simple test light.

1788129395174.png
 
Will a third pin be anything to worry about, like this one from Amazon?
The original female plug only has two receptacles used, and it looks like the third is empty. So the third pin of this relay would actually send and receive no signal.
Other than that extra pin, it looks the same.
Original relay after the screenshot from Amazon...
 

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Sadlsor said:
Will a third pin be anything to worry about, like this one from Amazon?
Click to expand...
No, Honda brings an unnecessary green ground wire to the signal socket for some reason.

A regular two-wire flasher, with or without a few inches of wire attached, is all you need.

Don't buy one unless you determine yours is the problem. The jumper test is the check.

(Do NOT jumper to the third (ground wire) terminal!)
 
Larry Fine said:
If you don't have power at the flasher, everything else is wasted effort. Buying parts is a terrible troubleshooting method
Click to expand...
Seems another Larry around here, subscribes to that same theory... and you're both right.
Just checked, and there's power at both front signals with the key on.
 

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Sadlsor said:
Seems another Larry around here, subscribes to that same theory... and you're both right.
Just checked, and there's power at both front signals with the key on.
Click to expand...
Yes, those are the running lights, the dimmer of the two filaments in each bulb, the ones that each turn off when you turn the signal switch to that side.

But, you have not determined why the signal is not coming on, front or rear, left or right. When something affects both sides, it's in or before the signal switch.
 
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