Electrical fault, heating up earth wire with no ignition on?

[ollieamb]

Recently used the car, all ok, parked up and left for a few weeks, went to start at the weekend and it came across as though it had a flat battery, engine turned and just died off, tested battery and tried another battery, batteries all good.

Car won't turn, checked all the wiring and found a few suspect earth cables so replaced. When I connect the battery an earth wire from the loom to the positive earth of the battery gets very hot very quickly, obviously I removed the battery quickly, solenoid only makes a click noise and won't start / turn engine.

Any ideas as I've not really touched anything? Earth to starter is good, earth from engine to body is good? All wiring seems ok, what I can see that is??!!

Any suggestions would be helpful as would like a run out over the bank holiday.

Many thanks Oliver

[vee12eman]

Hi Olliver,

Is the main earth lead from the battery to the car chassis/body in good condition, or even connected? It sounds as if the car is trying to earth through the loom rather than this large thick cable which sometimes frays, usually near the terminals. The loom cable will not be heavy enough to earth the starter motor sufficiently to turn the motor and will quickly burn out, probably damaging the rest of the loom and other components in the process. Also check the similar cable which earths the engine/gearbox to the chassis - I'm not a Series one man, so I don't know exactly where they are located.

Sometimes the earth value from battery to engine and body can appear to be good, even though the cable is frayed, as the multimeter used to test it looks only at continuity at a low value of current - dependent on the size of the battery in the meter - normally a small 9V battery. This is much smaller than the current drain when the big 12 Vbattery tries to turn the motor. Current will always take the path of least resistance, which appears to be the loom in this case.

Regards,

Simon

[christopher storey]

If on connecting the battery a wire gets hot without any load being used, then you sound to have a short at some point . If you have a multimeter which has a current setting , or better still an ammeter which will take a significant load , connect it to the earth lead and then touch it to the battery - if it shows any flow then you have a short . The first place I would look is in the let down panel . Loose or disconnected wires here are a real menace, especially if they come near the ammeter connections . Another thought - it sounds as if this can only be on an unfused circuit , so check first your brown wires, and then white wires

[ollieamb]

Thank you for your advice, had the car in bits today and found a few suspect wires, all fixed now however starter motor now packed up! Back to the spammers tomorrow!