How to find a short

[dan's 95 green SHO]

I just blew another alternator 3rd in 3 months of car running ******* me off. (This with the dead moonroof and all) The shop says I must have a short, but I am starting not to trust these guys because I just got my tranny rebuilt from there and it is slipping in 2nd and 3rd. How can I test for myself if the Car has a short or to see if they just gave me a crappy alternator??? I am electrically ********

 

[SHOZ123]

Get an amp meter. You need a meter that will read under 1 amp. Then disconnect the battery. Then connect the amp meter to the battery and the positive cable.

This will show you the current draw. Normal key off draw is around 50 milliamps. If the amp draw is higher start pulling fuses one at a time until the amp draw drops to the 50 milliamp level.

 

[shotimev6]

you can get a short finder. plug it into the circuit you want to check via the fuse then run the sensor along the wiring harness.it will beep when the short is found. its a couple hundred bucks from snap-on. dont know if theres anywhere else you can get one.

 

[pete c]

If you are getting an intermittent short, the symptom should be a blown fuse, not a dead alternator.

Check your fuse panel. Make sure you have the correct amperage fuses in each position. Someone before you may have got tired of replacing 5 amp fuses and went to a 20 amp slow blow.

When driving at night, do you notice your head lights dim at all? Mine does momentarily from time to time, but, I believe this is the AC clutch kicking in. If you have a short bad enought to **** the alt, I would think that your headlights would be more like strobe lights.

I would bring it to another garage. One that rebuilds trannies (badly) probably doesn't know a **** of a lot about electrical systems.

 

[89 black SHO mtx]

try a voltage drop test across the alt wiring harness. i had one do that and it turned out that the alt wasn't going bad but wasn't getting a connection due to corrosion in one of the connectors. if you have a dvm then set it to dc and put the positive lead to the alt output and if you have motre than a .5 volt drop you have a bad connection or a bad wire there somewhere. good luck it can be very frustrating finding those, Ken

 

[dan's 95 green SHO]

Thanks guys...brought it to the shop after testing everything and yes the 3rd alt is definitly defective...ahhh yes Yamaha whatever later thanks

 

[projectSHO89]

Yamaha didn't make the alternator.

It was made by one of Ford's vendors.

Steve