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volt problem HELP

jarredsoon

jarredsoon

Gold Member
PLease help.....

My cars batery gauge and the scan master show about 9 volts!!!!

I place a volt meter to the battery and it has 12.5

I check the alternator with car running and it is 14, battery with car running is 14 too.

I probed the harness to the ecm and it is 12.5 with motor off, key on.

Car wont start unless I put a battery charger on it, and then even when it does start the scanmaster tells me the bat is at 9 volts???? But I know the bat has 14 when car running????????

I checked the grounds by the battery and they seem good, grounds to the engine seem good, all tight and clean.????

Please help????

Thanks, Jarred.
 
Go to General chat/Pearl of wisdom for folks with no start problem (fast400) it might help? :detective:
 
You may want to relook at your battery. If the alternator is putting out 14v while running it's maybe a bad cell in your battery.
bob
 
I am using a new battery and I put in another known good battery from another car in and still same problem.

I know bat and alt are good, but somewhere in between that and the dash must be bad, why would the car not want to start if there is good battery volts???

I dont' get it.
 
ECM is the next thing I would think of...
Provided you already checked starter, solenoid, vats, etc,etc.
 
Fast, those prongs on the seleniod, are they inside the seleniod, meaning I have to take the starter and seleniod off the car and open it up?? I am unclear as to the desrciption of what to do on the Pearls of wisdom thread.

As for the ecm I did put it in a friend's grand national and it started that car just fine, so I am assumming the ecm to be good. and I did probe C 16 hole in the ecm wiring harness and found it to have 12.5 volts with the key on and engine off.
 
Fast, those prongs on the seleniod, are they inside the seleniod, meaning I have to take the starter and seleniod off the car and open it up?? I am unclear as to the desrciption of what to do on the Pearls of wisdom thread.

As for the ecm I did put it in a friend's grand national and it started that car just fine, so I am assumming the ecm to be good. and I did probe C 16 hole in the ecm wiring harness and found it to have 12.5 volts with the key on and engine off.

Jarred.
 
You do have to take the starter off. The prong on the solenoid is the larger threaded one that has constant bat+ coming to it. To access it you have to take off the two screws holding the plastic cap around the solenoid. Once you loosen the cap you'll be able to lookback side. You should have two raised prongs on the back side of the bat + terminal of the solenoid. If one is worn down, you can turn the entire threaded part 180 degrees so the other prong makes contact with the metal plate in the solenoid
 
Well the car starts when ever I put the bat charger on for about 5 min before I try, so could it still be the seleniod prong?? I am gonna check the prong after work tonight and see if it helps.
 
my car has a volt booster on it too, I am thinking that may have something to do with this??? Has anyone else had issues with their volt booster?? I am going to check the seleniod and volt booster hook up on the back of the altenator tonight.
Jarred.
 
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