10 replies to this topic

[AussieJohn]

The brake light on my 2002 TDM900 stopped working. I have had the whole tail/brake light stop before because of the insecure way the earth lead is held in place. This time the tail light was working just no brake light, so "must be the bulb" I thought and I pulled it out to replace it when I got home.

 

Checked the bulb and it is OK, tried reseating it and another bulb no luck. Got out the multimeter I have 12V on the connector in the bulb socket when the brake is applied. Didn't make sense, if there is 12V when the brake is applied then why not light up the bulb, In frustration I cut the bulb socket off and bared the wires. Again I had 12V between the yellow brake wire and the black earth when the brake is applied, but when I put these wires on the bulb it doesn't light up. When I used the blue tail light wire and the earth I can light up both filaments of the bulb.

 

Tell me, am I going crazy or is there some explanation?

Edited by AussieJohn, 03 August 2014 - 05:42 am.

[Rallyist]

corroded brake switch not supplying enough current to the bulb is my opinion.

[Wildbill]

Put the bared off cut wires directly to the bulb to confirm Rallyist's diagnosis.

[AussieJohn]

I have put the bared wires on the bulb, no effect. Brake switch it must be but I can't see why I am getting 12V at the wires end. Thought it would be a reduced voltage.

[Wildbill]

Voltage will show correct until load (bulb) is placed on it.

[Matt101]

It will read 12v but the amps/current is reduced so not enough to light the bulb. Give the contacts in the switch a good clean and all should be well.

[Daveb]

Had a similar problem with my old 850, no brake light, in the end I changed the rear brake light switch

Problem solved

Edited by Daveb, 03 August 2014 - 12:20 pm.

[TKH]

Aren't the bulbs both brake and rear light? Have you checked both as working?

[AussieJohn]

Yes TKH, both filaments will light when they are in contact with the tail light wire.

[Geordie Guy]

This is a bit fididly but I have soldered wires on to a bulb and connected to live and the earth in the bulb socket, this checks that the socket works and if it lights up. its the contact of the bulb in the socket that's wrong. If it dose not ........ Do the same in the dark and see if the bulb filament shows any a faint glow, that shows that the amps are low and its has to be a resistance issue with something in the wires leading to the bulb ( brake switch?)

 

Good luck.

[JBX]

This looks like a ground wire fault.