intermittant non existant electrics? baffled...

[deafasapost]

just a quick one really, but over the last say few months, my car just loses all power as if their is no battery at all, ie totally removed from the car....

starts, drives absolutely spot on, but very occasionally, whilst driving it seems to hunt, doesnt lose power but it feels like rapidly pressing/coming off the accelerator pedal. whilst its doing this, the volt meter goes from its normal 13.5 volts to about 14-14.5v. as soon as i turn off the engine, all power is gone from the car, like someone has just pulled the leads off the battery. to resore power, i wiggle the leads connected to the actual battery, and then all is well, BUT my problem is that the leads are both very secure to the battery terminals and the earth lead to the contact point from the battery to the body is secure and clean! what can be causing this to happen and is it a problem any of you guys have come across?

thnx, Al.

 

[VanhireBoys]

Try looking around the starter and alternator for a bad connection... And take a look at the heavy guage wire from the + side of the battery to the engine compartment.... It could be a dodgey engine earth as well .. Connections may be ok at startup but once they heat up they would fail

Make no assumptions - anything is possible..!. Check the likely suspects first

 

[deafasapost]

cheers Donal.
imo, everything looks fine, but i'll take a look this weekend to see if i have any loose connections at the alternator/starter motor end and at the earths. anything else to look at? my electrical knowledge is, well, quite frankly next to non existant so all pointers would be greatly recieved.

ta again.

 

[alwigley]

Check all the earths very carefully - some are quite well tucked away and positions vary on some models, but prime culprit could be the join from back of teh engine to the firewall/bulkhead. Otherwise could be dodgy ignition switch ?

 

[deafasapost]

i dont think its the ignition switch, in fact i'm 99% sure it isnt. probably an earth as you guys have said, so looks like i'll be busy. it doesnt happen all the time tho, so something just works loose i think or loses contact somehow.

 

[Hairyarse]

From memory there's a small earth wire attached to the steering rack.If this was loose then I don't know if it would cause all the problems you're having but worth a check

 

[Mike_Pollock]

I'd be looking at the ignition switch - its the moving item that controls almost all of the electrics.

 

[deafasapost]

if it was the ignition switch, then would it cut all power as if the battery was removed from the car? there is nothing when it happens, all power is non existant. wiggling the earth wire from the battery to where it earths in the boot solves this and i have power, but i've looked and there is no breaks or corrosion.

 

[36270k]

Sometimes breaks can be found inside crimped cable ends. I would replace the earth lead between the battery negative and the body and see if the problem still occurs.

 

[Mike_Pollock]

Does the boot light (or any other item become live that you can see) come on when you wiggle the earth lead? (When it has lost power etc)
If so, its either battery earth terminal inside the battery or the lead, and as 36270K says they can go in the terminal clamps also they can corrode.

 

[deafasapost]

yes, all electrics come on when i wiggle the batteries earth, cheers for the advice!!! never thought of the clamps themselves tbh!!!

 

[Mike_Pollock]

If its really ON /OFF I'd look at the battery. Sometimes the post can become detached from the actual plates.
Look really closely around the base of the earth post when wiggling looking for any movement.

 

[deafasapost]

its just like taking either the positive or negative off. doesnt happen all the time but is annoying. the battery is 2 months old so is under warranty. i'll look at the posts to start with then the positive and negative leads and take it from there. thanks for the advice and pointers, much appreciated []

 

[deafasapost]

looked at the possible causes on this yesterday, all looked good. with losing everything, i think its at the battery end so disconnected both pos and neg, cleaned and re-connected. checked the negative coming from the body to the neg terminal on the battery and looks A1.no breaks or corrosion. if it happened before, it was usually under load, no probs yesterday, . took it for a good spirited drive and ran perfect. i can only summise that it was a dirty contact but will keep an open mind just in case, otherwise it can only be the battery itself (i hope!) and thats under warranty so can be swopped.

cheers for the help guys