Electrical short circuit somewhere. Help please???

[notf1ack]

Hi

I've been having problems with my car cutting out for a while and have only just worked out what's causing it. Basically if the car is cold or has been sat in traffic for a while and it has something like the air con or radio on at the same time the engine dies and there is not enough power to drive it. We thought that maybe the alternator had gone so took a volt tester to it but that seems to be okay. The only thing that we could find which drained the power was the brakes. As soon as we applied the brakes the volts dropped massively so we're assuming it's a short somewhere in the wiring.

So my question is, has anyone else had this happen and have any ideas about where we can start looking for the problem area. I get the feeling it's going to be like looking for a needle in a haystack and was hoping somebody could give me some pointers as to where to start looking.

Thanks.

[Tintin]

I take it you were testing volage at the battery ?? if not you should be , you should probably see about 14v when the car is running , that means your alternator is fine , what are you seeing when you apply the brakes ???

The only places I can think of that have power on the braking system are the ABS unit , the warning light and the brake lights , would seem strange to me for this to be the cause of the problem but I'm not an auto electrician just a normal one so I could be wrong

I'm doing some work on the car today so if I get time I'll check the voltages with and without the brakes and have a quick peek at the ABS unit

A possible quick way to cut down on the fault finding would be to remove the switch or better one of the connectors of the brake peddle switch , don't know how easy his is to do on an FD as I've never looked at it , if your problem goes away then you have a problem on the lights circuit which could be a pig to find if not its either not the brakes or its around the ABS which shouldn't be too hard to find

[notf1ack]

Hi

Yes it was tested at the battery. The voltage was at 14 with the engine running and stayed the same with everything on (radio, lights, air con etc). It dropped to about 11.5 when the brake pedal is pressed though.

Thanks for the tips on the fault finding hopefully it's something simple...

[shortcircuit]

if the fault is on the abs system rx7city.com has pdf files with wiring diagrams and tests to carry out which might help .

[Tintin]

Didn't get chance to have a look at what mine reads as it was raining when I finished servicing the car I'll try and remember to do it tomorrow