iomlt Posted December 1, 2009 Share Posted December 1, 2009 Hello all, I have a 1994 3.9i Auto and the brake lights are permantly on. I have tried a new (known to be good as i borrowed it from a simular vehicle) brake switch. and still the fault is happening. usually when you select a gear (auto) you have to press the brake peddle but i dont have to which would normally point me back to the brake peddle switch but like i say i have replaced this. Any thoughts? AL Quote Link to comment Share on other sites More sharing options...
K88 MUD Posted December 1, 2009 Share Posted December 1, 2009 Wrong switch adjustment or a wiring fault Quote Link to comment Share on other sites More sharing options...
mobyone Posted December 1, 2009 Share Posted December 1, 2009 yep, brake switch adjustment. you can test the old brake switch before you fit it properly, and if the brake lights go out when connected but not in place, then you know it is adjustment. failing that, you probably have earth probs such as the wire the switch is connected to could be frayed and the wire is bare in places and touching metal. richard Quote Link to comment Share on other sites More sharing options...
pw8757 Posted December 1, 2009 Share Posted December 1, 2009 I agree - also I've recently learnt (after wasting a lot of my time ) that the only way to guarantee a known earth is to connect the negative on the continuity tester to the battery negative terminal................................this tip was in LRO this month, after the aformentioned time-wasting session.............................. Quote Link to comment Share on other sites More sharing options...
iomlt Posted December 1, 2009 Author Share Posted December 1, 2009 I have tried the switch out out while connected (electrically) and still on. so i guess its wire tracing time...... just wish it would be a known fault..... looks like i aint so lucky thanks for the reply's i'll keep looking Quote Link to comment Share on other sites More sharing options...
mobyone Posted December 1, 2009 Share Posted December 1, 2009 if it was not the switch, i would remove the lamp/lampss and clean them up. also clean the lamp holders and check their wiring is solid and earth is clean. if they are rusty or charred, they will conduct. either will be there or like i said, perhaps the brake switch wires are chafed. it is not likely to be anywhere else. are both lights on at the same time? are they on when the switch is disconnected? i hope this saves you some time. richard Quote Link to comment Share on other sites More sharing options...
iomlt Posted December 1, 2009 Author Share Posted December 1, 2009 thanks for the clues. yep both lights on. i'll have a play tomorrow and see what i can find thank you Quote Link to comment Share on other sites More sharing options...
Peter Posted December 3, 2009 Share Posted December 3, 2009 BTW Did you check the Brake fluid level, at that will make the low fluid sensor switch the lights on. Quote Link to comment Share on other sites More sharing options...
cipx2 Posted December 3, 2009 Share Posted December 3, 2009 BTW Did you check the Brake fluid level, at that will make the low fluid sensor switch the lights on. I don't think so. It will switch on the red warning light in the dash, not the brake lights on the rear of the vehicle. Quote Link to comment Share on other sites More sharing options...
iomlt Posted December 5, 2009 Author Share Posted December 5, 2009 i got the truck plugged in today. there was a fault on one of the switched but that was for the cruse control..... made no odds to the brake lights. when routing around i have found aload of wired rubbed through. i'll sort these out tomorrow and fingers crossed Quote Link to comment Share on other sites More sharing options...
iomlt Posted December 8, 2009 Author Share Posted December 8, 2009 OK, we are sorted.. traced the brake switch wire, goes off to 5 places. it splits off halfway basically side of the tunnel passenger and it had melted alot of wires within the loom. so cut and sorted them out and re wired all the brake light wires to each device. all working! I was thinking of wiring the brake light straight to the rear lights but this disco has abs and the likes so had to do a proper job. lmao Next job now is to replace the auto gearbox cooler, and start burning some fuel! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted December 8, 2009 Share Posted December 8, 2009 If they melted, why? There is a hot spot around the transmission tunnel/passenger rear floor which gets VERY hot if the exhaust heat shield is missing from the centre box -is this in the same sort of area? Quote Link to comment Share on other sites More sharing options...
iomlt Posted December 8, 2009 Author Share Posted December 8, 2009 If they melted, why? There is a hot spot around the transmission tunnel/passenger rear floor which gets VERY hot if the exhaust heat shield is missing from the centre box -is this in the same sort of area? It is around that area but wouldnt say it was caused by that. i think its more or the wires rubbing over the years. i have taped them up and put the whole lot in a conduite so hopefully cured this problem. Time will be a judge of this... Quote Link to comment Share on other sites More sharing options...
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