car running.disconnect batt and vehicle dies...

[crazydriverz]

i was testing my temperature switch because the gauge dont work. so i was running the engine and had to move the battery out of the way (by disconnecting it totally) to test the temp switch and the vehicle would die within 15 secs of removing the battery. is this a problem i need to fix before we get more snow here in michigan? would it be a alternator problem?

[danielsatur]

That's like pulling the plug on your electric fuel pump, and turning off your computer!

[AzTumbleweed]

I can't say about Escorts but it used to mean that your alternator was bad if a car did this. It should run without the battery and the alternator provides electricity. But I really don't know nowadays. If you haven't been having any trouble then I'd say leave it alone.

Turn on your ignition and disconnect the temperature sending unit. Check the gage. Then ground out the wire that goes to the sending unit and look at gage. On one of these the gage will peg out and the other it won't move (forgot which). If it doesn't then the gage is bad. If it does then the sender may be bad.

[danielsatur]

Older automobiles could get away from a disconnected battery, but newer
Auto's can't!

[crazydriverz]

ok ill give it a try and see what the temp needle does. as for the stalling i can see how newer vehicles would need a battery to stay running. i guess my thoughts were alil old fashion.

[denisond3]

I have three 2nd gen. Escort LX's. I know two of them will run, or idle anyway, with the battery disconnected; and I never tried it with the 3rd one. I suspect its a function of how agreeable the voltage regulation function is. Yes the alternator can produce plenty of electricity, but even a very brief interruption to that output (which is controlled by the regulator) would result in the engine stopping. Something as transient as the a.c. compressor cycling might be enough to cause the engine to stop, or dirty brushes or a worn slip ring on the field coil.
Since there is no service procedure that calls for removal of the battery with the engine running - I wouldnt do it routinely. But neither would I consider there was anything that needed fixing if it DID stop when I disconnected the battery.

[crazydriverz]

I haven't been able to test the wire coming iff the temperature switch. I need a second person. However I did run the vehicle for about 5 mins .turned it off,disconnected the battery and hookked up a multi meter(set at 20k) and was reading the temp switch. It would start at about 10.+ then climb too 16.+ would that mean my temp switch is still good?

[AzTumbleweed]

Originally Posted by crazydriverz

I haven't been able to test the wire coming iff the temperature switch. I need a second person. However I did run the vehicle for about 5 mins .turned it off,disconnected the battery and hookked up a multi meter(set at 20k) and was reading the temp switch. It would start at about 10.+ then climb too 16.+ would that mean my temp switch is still good?

It would sound like it is working.

[Intuit]

From what I've read elsewhere, disconnecting the battery on an electronically controlled vehicle is about THE WORST thing you can do.

As I understood it, the battery behaves like a big capacitor. Yes, it takes care of volt(amp) drops, but more importantly it filters amperage spikes! Minus the battery, you're risking rather expensive damage to your vehicle's electronics.

From my work with electronic devices I can say, electrolytic capacitors don't last forever and it wouldn't surprise me if most of them in nearly every Escort are bad. Even good, they likely do not have enough capacitance to handle a serious spike, but they're being bad means virtually no protection when the battery is disconnected from a running system.