View Full Version : Brake lights constantly on!!
So my bro's phase 1 passed it's mot today, when it came back from the mot garage the brake lights were on constantly?? it was compleatly fine beforehand.
First thing i thought was the switch on the pedal, had a play with it to no avail then removed the wiring from the switch compleatly and the brake lights still stayed on.
Anybody have an idea what i should be looking at as I'm stumped:confused:
UnstableCable
11-04-2012, 19:29
So my bro's phase 1 passed it's mot today, when it came back from the mot garage the brake lights were on constantly?? it was compleatly fine beforehand.
First thing i thought was the switch on the pedal, had a play with it to no avail then removed the wiring from the switch compleatly and the brake lights still stayed on.
Anybody have an idea what i should be looking at as I'm stumped:confused:
Sounds like a bad earth to me!
Check all the earths, think the earths actually under the rear lights so will have to remove them and check they are good!
Ok, checked all the earths, all seems fine, checked all the fuses, all seems fine, can't find anything obviously wrong.
Sounds like a bad earth to me!
Check all the earths, think the earths actually under the rear lights so will have to remove them and check they are good!
Surely a bad earth would make them go off constantly?? We are really stuck and have had to leave it for today. Does anybody know if there is a relay for the rear lights. Which could off broken down and is causing a back feed. In a world of pain! Please help :(
UnstableCable
11-04-2012, 21:41
Surely a bad earth would make them go off constantly?? We are really stuck and have had to leave it for today. Does anybody know if there is a relay for the rear lights. Which could off broken down and is causing a back feed. In a world of pain! Please help :(
You would think so but I got pulled by the old bill once for the brake lights being on constantly and it turned out to be a bad earth.
So you had back lamps off is there a plug for each lamp
check the switch near the pedal is functioning.
We checked the earths on the rear light clusters and they appeared to be ok, are their any other earths that we should check.
The switch appears to have no effect on the lights, even with the switch on the pedals disconnected the lights are still on, when we bridged the connection they still remained on.
footwell earths also clean up the connectors there to,check the actual lights for corrosion as well.
:)
Have you checkd the circuit board the bulbs plug into for any corrosion/oxidation?
We have had the rear light clusters off and given them a good check over they are fine, actually in really good condition, as is the earth behind the passenger side rear light cluster.
We did do a bit of wiring yesterday, we wired the boost guage into the dimmer switch and the afr guage into the cig lighter. Paranoid we did something wrong we put the wiring back how it was to double double check and the lights still just came on with the ignition.
Thing was we drove it probably 40 miles from his house to mine and the brake lights were fine, gave it to the mot garage to drive to their place and mot it and it came back with the lights on constantly. Very strange.
Would it be worth running an extra earth from the afr guage just to rule that out?
Where is the earth in the passenger side footwell?
Alastair
12-04-2012, 11:39
We have had the rear light clusters off and given them a good check over they are fine, actually in really good condition, as is the earth behind the passenger side rear light cluster.
We did do a bit of wiring yesterday, we wired the boost guage into the dimmer switch and the afr guage into the cig lighter. Paranoid we did something wrong we put the wiring back how it was to double double check and the lights still just came on with the ignition.
Thing was we drove it probably 40 miles from his house to mine and the brake lights were fine, gave it to the mot garage to drive to their place and mot it and it came back with the lights on constantly. Very strange.
Would it be worth running an extra earth from the afr guage just to rule that out?
Where is the earth in the passenger side footwell?
Front left hand side of passenger footwell under the plastic bit.
I have the wiring diagram labeled up in the garage, but i think from memory the switch on the pedal is the + line not the earth. That tells me you have a short giving the bulb 12v somewhere, and the earth at the back of the car by the cluster is good.
Check the connecting harnesses in the front footwells - either side behind the square cover - for shorts, disconnect them, then work backwards with a fluke to find where the + 12v is coming from.
Alastair
12-04-2012, 11:40
Have you checkd the circuit board the bulbs plug into for any corrosion/oxidation?
Good point - a green scotchbrite/pan scourer on the tracking is a good idea! Although it is a bit strange for both to come on from this?
Could this short off happened due to us over loading the ciggy lighter??
Just so you all know. Haz took my dash out and we found 1039274829029 live wires all over the show for no reason. Stripped all the crap not needed out and tested. Brake lights back to normal. Also when the previous owner drilled a hole in the dash he snipped a few cables which we sorted aswell. Top effort to my mate Haz he took the dash out, sorted the wiring then back in all in 6 hours. Different gravy.
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