Hazard switch lights up? Also with horns?

teahead

aka "Rob"
Site Donor $
Messages
6,453
Reaction score
1,887
Location
Tacoma, WA, USA
Is it normal for the hazard switch to light up (not flash) with the headlights on? Dims also with the dimmer
 
Spooky wiring. Just started or reoccurring problem? Any work done on the electrical system recently?
Cant see how the hazard warning would dim as the hazard is on a different (permanently live) circuit. Perhaps a dodgy earth in the indicators system some where. But the horn honking with the lights ???
Its not April 1st by any chance!!!!
 
I replaced the ignition switch recently. I also changed the hazard but didn't notice until now it lights up with the headlights.


So I assume the horn lights is not normal?
 
You may want to recheck everything again and I am sure you'll find the problem
reminds me of a funny story 30 years ago, we replaced a Nissan front clip ( including the A post).
It had to be rewired by a Nissan Mechanic, after he was done when we honked the horn the wipers would work, of course he fixed it by going back and rechecking all the wires again!
 
And fuel gauge moves with turn /hazards

How much does the fuel needle move? And does it do this with the engine running? The needle moving just a bit with the engine off is probably normal - the battery voltage will fluctuate as the turn signal bulbs go on and off.

But if the needle moves with the alternator running, then I would guess that your instrument cluster isn't grounded well. So when the turn signal indicator bulbs receive current, some of it has to flow through the fuel gauge circuit to reach ground. A quick test would be to put a jumper (a foot of wire with two alligator clips) between the instrument cluster ground and a known good ground.

...and my lights light up when honking the horn

I have no idea how that could occur! When you say "lights" do you mean instrument? Parking? Turn signal? Headlights? Or all?
 
Last edited:
How much does the fuel needle move? And does it do this with the engine running? The needle moving just a bit with the engine off is probably normal - the battery voltage will fluctuate as the turn signal bulbs go on and off.

But if the needle moves with the alternator running, then I would guess that your instrument cluster isn't grounded well. So when the turn signal indicator bulbs receive current, some of it has to flow through the fuel gauge circuit to reach ground. A quick test would be to put a jumper (a foot of wire with two alligator clips) between the instrument cluster ground and a known good ground.



I have no idea how that could occur! When you say "lights" do you mean instrument? Parking? Turn signal? Headlights? Or all?

Well..car won't start at the moment (fuel pump).

Headlights come on.

The wires under the dash is pretty clean. Not a spaghetti / rat's nest.

Maybe it's a bad horn relay.

I'll run a ground wire from the battery to the gauge housing to check the ground.
 
Headlights come on....Maybe it's a bad horn relay.

I have to admit that I have no idea how the horn and headlights could interact, so yea, maybe it's a bad horn relay. But somehow, I think your horn relay is innocent.

A test would be to disconnect the signal wire at the horn relay - the wire that is grounded by the horn button in the steering wheel (marked "86" on my Prospero wiring diagram). Then try pressing the horn button; if the headlights still come on, then the horn relay isn't the cause. A second test: while that wire is disconnected, ground the signal terminal on the horn relay - if the horn honks, but the headlights stay dark, that also proves that the relay is OK. That is my guess as to what will happen.
 
Last edited:
IMG-20111231-00174.jpg

Sorry, which one in the engine compartment is the horn relay?
 
Yes, 8-prong with the words "Hazard" on it. Same as old one that was replaced.

Really weird for it to light up like that but if that's correct...


The other issues has to be a bad ground I assume
Did you unplug the wires going to the hazard housing for any reason? ....perhaps for removing the under dash piece?
 
Horn has a green/yellow wire, hi beam is white or white/violet. Since you have a third can relay maybe someone added a low beam relay, it has a yellow wire. Just unplug and examine wires or energize each component and feel which relay clicks when turned on.
 
Back
Top