TOM TOM Lighter SMOKE!

[Deleted]

Bought myself TOMTOM . I took out the lighter switch/knob, inserted TOMTOM lead waited a few moments, then Smoke starts to por from switch/control. Nasty smell, disconnected quickly before another 3 litre went to the promiised land!
Where did I go wrong, nice man said it fits any car! Was he right?
Please don't laugh a comment would be appreciated.
Tony

[harvey]

I would think there's a fault in the socket. Does the lighter work if you try that. TBH if you want to use that type of thing I'd fit a new one anyway. They always end up in a disgusting state inside.
I assume the car is Negative earth as I would think the TOMTOM is polarity sensitive.

[Phil Nottingham]

Only Mk3's were negative earth as standard so unless it is or you have an earlier model that has been converted then you may have real problems now

[johnwp5bcoupe]

For sure if it's not a Mk3 it is +ve earth as Phil says and reverse polarity will have blown the Tom Tom your only comeback would be if the salesman said it "will fit any car" unless he was an old salesman he would not have heard of +ve earth! BUT their comeback will be read the installation manual it seem strange that the device is not RV protected internally simple enough with a diode good luck

[glennr]

Why was positive earth used? any benefits?? why then is negative earth now seemed the norm

[miguel]

... and does not negative earth have also a antirust benefit? (in a small scale)


PS: One of the marvelous thing about the forum is that I cant hear and see you laughing...

[harvey]

Sept 11, 2008 21:47:22 GMT miguel said:

... and does not negative earth have also a antirust benefit? (in a small scale)

Indeed it does, alledgedly. Doesn't seem to have worked very well though.

[Phil Nottingham]

Single pole wiring only became common and necessary in the early 30's as more electrics were used and steel bodies became the norm - even Rover saloons of early 30's were fabric covered wooden framed bodies so chassis earthing was not an issue. Even chassis were part wood before then and electrics were just confined to the magneto ignition as lights were oil/acetylene anyway. Mid to upper range cars all over the world tended to be positive earth for the performance and reliabilty so its not surprising that Lucas who supplied these all. US cars went "steel" far earlier and they too were mainly positive earth

Lucas were by far the standard suppliers of car/commercial electrics and ignition systems and they just plumped for positive earth as sparks jump better in the plugs and caused less erosion with a positive earth from and every one followed in the UK.

Elsewhere it was either or neither until it was put about that negative earth did have a beneficial effect on corrosion on both steel and aluminium bodies. Better plugs ignition systems and engine designs negated the spark plug advantage if there was one The rest of the world gradually moved over to the negative earth system by the mid 50's leaving just UK and some of its ex colonies on the positive earth system.

The introduction of transitors and alternators meade a common system essential and by the late 60's most British cars had changed over and dual polarity transister radios no longer needed to be made.

As to corrosion the difference was found to be so insignificant in the end it no longer mattered anyway P5's corrode no differently than P5B's and Mk3 P5's

[Deleted]

The car is Positive earth. Better a blown TOMTOM than a burning car. I will check tomorrow to see whether TOMTOM still works. It was hot when extracted but no doubt its had it.
Thanks for commenting.
Tony

[Warwick]

Tony, I'd still check the socket as Harvey suggested, even though you've found the cause. I plugged something into mine last year and blew the fuse. On closer inspection the socket was badly rusted internally and one of the contacts broke and shorted out against the case. I had to replace it as it was too far gone to repair or clean.

[Phil Nottingham]

Corrosion of the lighter body may have saved it - the heat from the element encourages rusting but the heat may have fried the TomTom's semi-conductors.

Its easy to convert to negative anyway - SEARCH

[glennr]

Thank you Phil

[johnwp5bcoupe]

The Tom Tom will draw very little current so would not produce heat in the lighter connector rusty or not rust would give a high resistance so less voltage and current, but if RP'd it would draw heavy curent within itself if it has no protection I would have thought the plug as per normal would have a small rated fuse in the centre contact and would have blown!

[PatMcCoy]

Yeah
I have one and i think John your right
Well my model has tomtom 910

[Eric R]

For what it is worth, when i drove my Mk1 6 cyl str8 from Italy through France my purpose built plug-and-go Garmin refused to load so i had to drive back with a wet finger in the air. Found that the car had been converted to negative earth ok but the cigarette (oops sorry, cigar lighter - 4got it was a Rover) had contacts deterioted. Removed and clean up - works fine.