So Why Did My Rav4 Catch Fire?

[Hoovie]

Well, nearly!

Fitted some Auxillary driving lights last year - Original (and very pricey!) Toyota ones bought from Kingo.

All been working ok, but last week I noticed that they had stopped working.  Did some checking and found it was down to the Relay failing (not very well sealed and water got in and corroded and seized the solenoid.

So I sourced from a local Auto Factor a replacement relay yesterday. The only difference between the original was:

a) no integral fuse (made a mental note to fit an on-line fuse)

B) new relay rated at 30A - original was only 15A (assumed this will do no harm, just a beefier relay)

I fitted the new relay - which was a direct plug-in fit with all the codes on the spades the same - 30 switches to 87, and relay between 85 and 86.

At the same time as fitting the relay, I also fitted new high-performance OSRAM bulbs, but the new ones were still rated at 55W same as originals.

Right, so that is what I did and went out last night..... On drive home, had the headlamps on and nice and bright, then got a bit of a flicker and spotlights stopped working  :(

Carried on home, and assumed relay had just prematurely failed 

Went to investigate this evening and checked relay still plugged in securely. Turned lights on. Soon as I put the main beam on, smoke started pouring from engine bay  :o .

Turned beam off - spots went off and then came on by themselves a few seconds laster  :o  Ripped open fuse box and pulled the 30A fuses and the spotlight loom was still burning up and glowing red!!  Had to run inside and get a pair of cutters to cut the power lead from the Battery to the relay to remove the power from the spotlights (and the amount of current drawn in this short time has drained the Battery enough that now won't turn engine!)

Virtually the whole of the spotlight loom has melted and is totally knackered. The relay looks externally like it had fused on going by the plastic melted on one of the spade connectors and the smell from it.

All I can assume at the moment is that the relay failed dramatically causing some catastrophic failure in the spotlight wiring and because there was no fuse in place for this spotlight loom (old relay had the fuse, new one did not and I had not fitted an in-line replacement) there was nothing to stop the current 

I will need to either buy a new set of toyota lights to get a loom (way too pricey!), build a new loom from scratch to replace OR maybe buy a cheap set of lights from Halfords or the like and use the wiring loom from it, but am a bit concerned as I don't really understand why this happened when the lights HAD been fine until the old relay failed (so the loom and wiring would have been ok at that time) and the only thing I then did was to fit a new relay - plug and play - and new bulbs - again, plug and play. 

Any ideas why has this happened??  Is it as simple as a rubbish relay and my stupidity in not fitting a fuse immediately?

[anchorman]

I think it probably is straight forward. If it was wired wrong it wouldn't have worked in the first place and it has somehow manifested itself in a dead short. Use a digital multimeter and have a look to see if there is continuity between each side of the realy. Just to check that we are thinking the same; The lights should have been connected to their feed by 30 and 87 and a feed from the switch to earth via terminals 85 and 86 = right?

Cheers

[local hero]

Wow Hoovie sounds pretty scary to me As you know I am not going to be able to give you any technical advice, (although i now have 3 lights in my boot + a switch) however whilst killing time in Halfrauds the other day I was looking at some spotlamps + it said on the box easy fitting using "RING" complete wiring loom available seperately.. so possibly might be what your after.. Sorry to hear of your near disaster, see its not only black cabs that burst into flames :D We have missed your "pimping" maybe your next pimp should be an underbonnet sprinkler system

http://www.ringautomotive.co.uk/product_li...2=8&cat3=47

[Hoovie]

I think it probably is straight forward. If it was wired wrong it wouldn't have worked in the first place and it has somehow manifested itself in a dead short. Use a digital multimeter and have a look to see if there is continuity between each side of the realy. Just to check that we are thinking the same; The lights should have been connected to their feed by 30 and 87 and a feed from the switch to earth via terminals 85 and 86 = right?

Cheers

I will have to go look at the wiring again to 100% confirm that, but pretty sure that is how it is.

took lenses out of spotlights and the offside light earth is badly melted (and the supply and earth insulation are fused together quite tight but the nearside light earth is unaffected. implies that when replacing the offside bulb it screwed up the wiring, but I never removed the earth plug (no need to) and the bulb supply spade was pushed in tightly into the connector - and I used ty-wraps as strain-relief when I fitted the lights so the wires could not be pulled hard anywhere where they may rub against metal. 

Another issue .....

This problem caused the Battery to pretty well die (clock actually reset the time so was very dead as some time) - could this cause the ECU to reset or similar?

Just back from a drive out to give the Battery a boost and the car was very hesitant accelerating and when I lifted foot off the throttle it was as if I had the handbrake on - definate slowing down using brakes feeling rather then just a normal slowing. Yesterday it was totally normal to drive. 

I recall reading that the ECU has to relearn after a Battery disconnection or something? 

Getting paranoid now!!  :(

[anchorman]

Hmmm

It would be wrong for me to say that it isn't the ECU but I am happy to say it is unlikely. A serious short circuit could have affected some semi-conductor devices but don't forget that engine braking can only be affected by engine compression and not some form of external retardation. Follow the loom back to source for the lights and see if there is any evidance of melting any other wires. If there is you might have to cut them back but if not, fix the bad bits, check for coninuity and earth leaks and then run the car a bit more. The mind is a powerful weapon when it comes to faults especially where apprehension is involved!!! You are probably just looking harder.

BTW, LH has made a little Subutio stadium in his boot and they play under floodlights.

[jedi134]

Yes after a reset/disconnect the ECU does have to relearn. The car can be erratic for a while, a good run on motorway, town, and stuck in traffic should sort it out, other than that its off to the dealer, they can adapt the ecu via their diagnostic computer.

Maybe the wiring loom was not able to handle the extra amps drawn from the new bulbs fitted? and as such gradually heated the wires up to the point they melted through the plastic coating and shorted. This in turn would have drawn huge current through the relay, probably fusing and melting the internals of the relay together, so you where not able to switch it off via the switch, and as not fused had unlimited current draw.

Or you tie wraped the + Positive to tightly into a sharped edged earth.

As it melted down into the lens i would think the problem started in the lens area.

[Hoovie]

thanks for replies, chaps :)

going for an approx 80 mile drive tomorrow to Edinburgh, so will get a nice mix of driving styles in then. I am definately over-analysing I think

The new and old bulbs were both 55W but just to make sure, the RAC chap put them on his little rig to check the current draw and the old light draw 5.3A and the new 6A so not much.

I did have a thought that as the bulbs were meant to be much more effective, they probably ran a lot hotter and thus the reflector bowl got very hot and I allowed the earth lead to rest against it when refitted the lense? - although how that would cause a short I don't know.

One thing I sure have learnt is the importance of having a fuse. I intended to wire one in this weekend, but using the lights even once without the safety of a fused supply was very silly!!