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Old 07-12-2004, 02:27 PM   #1
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Default Loss of electrical power

Good afternoon everyone,

I was hoping to get a little guidance on a 1995 pont bonneville - SE that I own. Recently she has stalled often and at the same time I notice many of my power accessories go away also. Actually I can even cause her to stall by trying to roll two windows down at the same time or turning on my defogger. I have cleaned all of the grounds. I have also tried to isolate the problem by pulling fuses and measuring resistance between the pos and negative terminal on the battery(with it disconnected of course). With the ignition key in the run position I am experiencing what I beleive to be a very low resistance between the battery terminals. Does anyone know what that resitance should be??? Also, if I remove the ignition fuses - my low resistance problem goes away. with or without the key turned on. I unfortuantely do not have a good schematic to work from and am a little lost as to all the components that pick up when the key is on. Can anyone reference a good location for a wiring diagram for that vehicle??? One last really stupid question I have - How do the relays pull out of this vehicle - I've fought with one a little - and it was kicking my rear!
Any help would really be appreciated!
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Old 07-12-2004, 03:11 PM   #2
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Did you also clean and scrub the battery terminals and connectors?
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Old 07-12-2004, 03:35 PM   #3
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Yes - I've cleaned everything I could find. I just read about a ground located in the passenger side door. I will look for that tonight. Other than that I have traced and cleaned all the other power connections and grounds I could find. However, I think that my system is shorting to ground and not just suffering from a high resistance ground. I'd like to know what people were getting for resistance between the Pos and neg terminals of the battery.
1. If you disconect the positive terminal. (You can disconnect the neg - but not necessary)
2. turn your ignition key to the run psoition without starting the car
3. Measure the resistance between the pos and neg battery terminals.
- What do you get for a resistance value. - I'm getting 5 ohms or less.

If some component in the run ckt is shorted to ground - or nearly shorted to ground - placing a load in that ckt might be like placing the positive alternator and battery leads directly to ground. This would drop the computer voltage to less than 9vdc and shut the car off.

- Is ther anyone out there who has tried this or who will try it in a normal system and let me know the results?

Thanks for your help!
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Old 07-13-2004, 06:25 PM   #4
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You can't really take a resistance reading across the battery with an ohm meter? Also, battery potential direct to ground = short. You should be blowing fuses somewhere there. Is your electrical system voltage dropping out when placing significant load on system? Monitor with a meter while operating the rear defogger, or some power windows to see what the voltage droop is on the system. How old is the battery? alternator?
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Old 07-13-2004, 10:01 PM   #5
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hey markwb,

Thanks for the post. - I'm not reading across the battery terminals - actually I am reading across the leads that are connected to the terminals - when they aren't plugged into the battery.
- Yes the battery voltage is dropping significantly when a load is placed on the ckt. - Thats what made me want to look at the load impedance the battery was seeing.
- With the ignition switch on - the lead impedance is int he dirt - around 3 to 5 ohms - I have a cheap mulitmeter - so that may not be a real good number - suffice it to say that it is far less than what my Ford truck sees in the same lineup - I know apples to oranges!
- That is why i wanted someone to duplicate my findings. The battery holds a solid charge with just the lights on also - over 12vdc and solid.
- Something in the ignition ckt is breaking down under load. -

Any Ideas??
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Old 07-13-2004, 11:16 PM   #6
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Ok, I understand now. There'* alot of things happening when you first turn the key. There are many parallel resistances (ignition relays picking up, and many other loads etc.) that you're seeing, so the 3-5 ohms might not be a bad number, I don't know for sure. And I'm not sure that is the approach I'd take. Try to isolate things out by removing relays & fuses if neccessary. Those relays are tough to pull out of the sockets. I've used a regular pair of pliers with a gentle touch for relay removal and that has worked. When you turn something like the rear defogger on, initially you'll see voltage drooping especially at idle, but the alternator sholud have full field applied and boost voltage back up to nominal value 13-14 volts after a second or two.
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Old 07-14-2004, 07:23 AM   #7
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Thanks Mark - Thats a good approach - Maybe I should do a load test on battery and get the alt checked at auto zone.
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