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Like the title says, my flasher/hazard light system doesn't work when the car body gets hot. More precisely, whether the car is heated up by the engine or the weather outside, after around 80F (26C), the flasher system stops working. No light on dash, no clicking sound and even the hazard button don't work.
I tried replacing the Flasher control module/relay, but that didn't solve the issue. I then tried to hard-wire the pins used by the relay/module to send the current to the bulbs (since it's easy to access) and the lights worked fine. This means that the bulbs circuit are working fine. But there is "something" that causes the current to not pass threw the flashers relay/module.
Any idea what could be the cause of this?
Here's a diagram of how I hard wired. The blue lines is the normal current flow and the purple line is where the system was hard-wired. [Please i
gnore the highlighted part and the arrows]
Yes. The wiring was tested when the car was both hot and cold. More precisely, when the flasher system stopped working, I checked the wiring system and hard-wired the module pin, which turned the flasher on. After that I reinstalled the mode/relay and it still didn't work.
I've tried heating up the relay and trying it when the car is cold and it worked.
That's why I concluded that there's "something" that causes the current to not pass threw the relay when the car itself is hot.
My guess is that the raise of temperature on the car increases the resistance of the circuit, causing the amps to drop. But, it drops so low that it dosent have enough current to magnatise the relay.
If my guess is right, then putting on LED lights should fix the issues since LED light consumes less electricity, therefore decreasing the resistance of the system.
I know this sounds confusing, but if somebody wants more explanation on my guess, I'll explain it.
Otherwise, if you guys have any guesses or any information that might be useful, I'm all ears!
There's not THAT much difference in resistance in the range of temperatures between whatever ambient temp you have and 26C. We're not pushing high amperage here. I'm thinking that the problem might be physical? What if you jostle the module while it's on, do you get any intermittent flashes?
Possible there's water somewhere in there that freezes in the cold, then melts and melts and shorts a connection when warm?
I tried to jostle with my 4 relays/modules, but it didn't make any difference. Also, since the circuit did work when hardwired, I doubt there's water freezing and stopping the current flow
If the circuit works when you bypass the relay there must be something up with the relay
The problem with the LED idea is that there needs to be enough current draw to get the flasher to work... and often thats why LED's cause problems in turn signal applications without having ballast resistors included in the circuit
Don't LED light require less current to use? If so, then wouldn't it help power up the relays in the module
Most flasher modules require a certain amount of draw to work properly... so they often don't work with LED without ballast resistors.
if the relay and flasher are OK then you have a wiring issue. Did you check the fuses and the grounds in that circuit?
Nope, I never replaced the fuse for the hazards. Why do you think that could be the issue?
Also, I found some info regarding the inspection of the connectors of the flasher relay/module. Once the problem re-occurs, I'll inspect the connectors according to the inspection information.
My guess is that either the power supply or the ground of the connector is bad since I didn't use them when I hard-wired
Quick update on what's going on: I managed to re-create the issue and I started troubleshooting the issue according to the diagram I sent in my previous message.
After running around with my multimeter, I noticed the power supply of my module isn't getting any current (Terminal A on the diagram). I then proceeded to remove the fuse and check if there's current passing there and... surprise... I'm reading battery voltage (12V) on BOTH ENDS!!! Keep in mind, once the fuse is removed, I shouldn't be getting any voltages on one side of the wire (at least that's what I think).
Since it was late, I decided to continue the troubleshooting task another day, but hey... I'm getting somewhere!
If you guys have any ideas what could be happening, feel free to type them here! I doubt it's gonna be easy to fix this.
Here's a picture of what's going on to understand better (once again, keep in mind, the fuse is removed, so I shouldn't be reading 12V that's red):
Last edited by airman3221; 01-08-2023 at 10:41 PM.
Quick update on what's going on: I managed to re-create the issue and I started troubleshooting the issue according to the diagram I sent in my previous message.
After running around with my multimeter, I noticed the power supply of my module isn't getting any current (Terminal A on the diagram). I then proceeded to remove the fuse and check if there's current passing there and... surprise... I'm reading battery voltage (12V) on BOTH ENDS!!! Keep in mind, once the fuse is removed, I shouldn't be getting any voltages on one side of the wire (at least that's what I think).
Since it was late, I decided to continue the troubleshooting task another day, but hey... I'm getting somewhere!
If you guys have any ideas what could be happening, feel free to type them here! I doubt it's gonna be easy to fix this.
Here's a picture of what's going on to understand better (once again, keep in mind, the fuse is removed, so I shouldn't be reading 12V that's red):
To be clear, you checked each fuse terminal end with one probe from your multimeter to the gnd of your battery (not a body ground), and the other on one of the fuse terminals? Or did you do it as pictured? One probe on each terminal?
I asked earlier if you replaced the fuse because fuses can fracture and cause intermittent issues like the ones listed, but not be noticeably "broken" to the eye. Ask me how I know. Don't use cheap ebay fuses either.
If you measured voltage according to your picture, your multimeter "replaced" your fuse and completed the circuit. You should still see 12V.
Terminal A will not show any current draw (how ever you measured current) unless your hazards are running.
Also has anyone mentioned to check your radio faceplate connections? thats where all of the connections for the hazard switch are.
For the first test (black 12V), I removed the fuse, set the multimeter to read DC voltage, put the positive prob (red) on the first terminal of the fuse terminal and the negative prob (black) directly on the battery ground.
For the second test (red 12V), I removed the fuse, set the multimeter to read DC voltage, put the positive prob (red) on the second terminal of the fuse terminal and the negative prob (black) directly on the battery ground. Something I'd like to add is that the voltage reading I get whenever I test this terminal is decreasing faster than the battery voltage and the voltage goes back up once I reconnect the fuse.
For the third test (red 0V), I set the multimeter to read DC voltage, put the positive prob (red) on the pin A of the connector and the negative prob (black) on pin F (since it's a ground).
One thing I'd like to add is that I did check if the pin F is grounding correctly by putting the positive prob (red) on pin J and putting the negative prob (black) in pin F when the LH turn signal switch is on and it showed me 12V (normal reading according to the voltage reference table.
Another test that I've done is to check for voltage when the fuse is connected by measuring the pin of the fuse with the positive prob and the negative prob (black) directly on the battery ground. I was reading 0V while the other fuses were giving me 12V. The fuse let's pass continuity btw.
According to the FLASHER UNIT INSPECTION>TERMINAL VOLTAGE (REFERENCE), Terminal A (power supply) is supposed to give B+ (battery positive = 12V) under any condition. That's why, when I measured Terminal A when the flasher were working, I was getting a constant stream of 12V even when the car was turned off. Another thing to add is that, to check if terminal A is related to the flasher system by being the power supply of the module, I tested if the flasher system works when I remove the hazard fuse related to terminal A and it didn't work. Once I put the fuse back, the flasher started to work again automatically.
I hope this answers your suspicion with the test I've done!
Good way to quick check grounds and circuits is using the continuity function of the multimeter
You can also use it to check across connectors as well. It can be a bit flakey sometimes and then you would want to check resistance....this works when there is corrosion and will show a higher resistance than expected
Nice tip to detect corrosion on ground, I never realized that checking the resistance can show the condition of the ground even tho it's working.
For the connectors, that's kinda how I'm planning to figure out what's really going on. For now, I know that there is a foreign system that's giving current on my flasher system wire. I'll try to figure that out then check for the continuity of the wires and see if there's other stuff that's messing up.
If everything goes nice, I might be able to fix this issue later today.
It took me a few weeks since I didn't have much time to work on my car, but I managed to fix the flasher/hazard system issue!!!
Like I said in my previous reply, the issue was the wire between the fuse and the module itself. It took me awhile to figure it out, but I fixed it!
There's not much else to say, so thank you very much for the guys that tried to help me with this. And, if ever some people have issues with their flasher/hazard system, I'll be more then happy to help them (since I pretty much know it like the back of my hand).
With this, my flasher/hazard system troubleshooting is now concluded.
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Last edited by JohnLennon; 03-27-2023 at 08:23 AM.
01-04-2023, 12:46 PM
