mustang 94 gt charging question

[Cangri]

Hi.

I have a stock 94 GT with 49,000
I notice that when I disconect the neg battery cable the car shutts down so I said alternator s busted. but I got it checked and they even got me a new one but still after the new alternator was install the car still shutts down when the neg cable is disconected from the battery. what could be causing this?
I also checked the alternator cable and I has power. some body said some thing like fuselink may be the cause?

 

[1TallMF]

First of all, I'll just be the first of possible many to say it, but that test is only suited for carburated cars (no ECU). It quite possible to fry some electrical components by doing this. And even if it were safe to do, I'm pretty sure the old trick was to remove the positive cable. Removing the ground will almost certainly shut the car off.

When you looked for voltage at the alternator, what was the reading? It should have been between 13.5 - 14.4V. If it was 12V or below, thats only battery voltage, indicating no charging from the alternator. Good luck

 

[HISSIN50]

1TMF took the words outta' my mouth.

The above-sentiments about the pulling of negative battery cable while the car is running are correct. There's a nice field that collapses when you do this and the voltage spike can wipe out electronics.

As requested, more info about what diagnostics you've done. Alternator charge cable reading vs battery voltage at a minimum are needed. There are two fusible links on the charge cable between the PS pump and the PDC.

Good luck.

 

[Cangri]

13.7 is the reading

thanks every body

I will check the fuse link the weird thing is that the alternator meter in the dash board is reading like 11.5 volts

 

[1TallMF]

wow, yeah, thats no good. But then again, you can't go by what the gauge says, its not the most accurate thing around. As mentioned, do check the battery voltage when the car is off, and then when the car is on. If they are no different, I wouldn't doubt the fusible link in the alternator charge cable is blown. You could even do a simple continuity test from the + battery terminal to the charge terminal on the alternator to avoid having to take the wire apart.


Edit: nevermind, I was too slow to write

 

[BlownFiveLiter]

Removing the negative battery cable should kill your car. You have no ground, so all the power coming from the alternator or positive on the battery has nowhere to go.

 

[1TallMF]

Thank you for confirming that. It made sense in my head, but I wasn't sure if it was the beer talking, lol

 

[BlownFiveLiter]

Darn Canadians and their powerful beer...