Low voltage problem in my T/A

Hi I'm having a concern about the charging system on my 98 T/A formula.
When I got it I notice that the voltmeter in the cluster was reading in the yellow area or lower when it was in idle in gear. If I put it in neutral the voltage picks up to around 12 volts. When it was running it will be around 13 volts. I took it to the auto parts and they hook the machine to it and they told me that the alternator was charging too low around 50 amps. I bought a new alternator and I test drive it today. The voltage when its runing is around 13 - 14 volts. When it is idling in gear it drops slowly close to the yelow but it hasn't hit the yellow area in the voltmeter in the cluster. The more stuff that I use like a turn signal the more it drops but not as bad as before( when it was hitting the yellow zone or lower). The car has never cut off. I'm been paranoic or there is something else wrong? I'm trying to get and external voltmeter to compare readings and make sure that the one in the cluster is not bad or out of range. Thanks.

it definately should not be dropping like that. do you have underdrive pulleys installed?

No it doesn't. As far as I know everything on the car is stock. I asked a friend just to confirm and he also told me that I don't have one. Thanks for the quick response.

My 98 T/A is dropping the voltage too low. When the car is at idle and in gear it will slowly drops the voltage to 11.9 volts depending on how much stuff is on (lights, wipers, etc.). When the car is running it stays around 13.2 volts. I check the battery while the car is off and it is 12.6 volts when i start the car is reads around 13 to 13.6 volts at the battery. The haynes book says that it should around 14 to 15 volts while the engine is running. I already put a new alternator on it because tha auto parts store checked it and they told me that it was only charging 50 amps. Even with the new alternator the voltage keeps droping. Could it be a bad connection or corrosion in the wires and/or terminals? Any suggestions will be apreciated.

could be a weak connection or a bad alternator

I've merged your 2 threads that you created about your low voltage problem. Please do not create more than one thread on the same topic, Thank You.

I've also moved this thread into the Problem Diagnosis sub-forum, which you can find listed at the top of the main forum.

Could it be a bad connection or corrosion in the wires and/or terminals? Any suggestions will be apreciated.

Quite so. Also take a look at the belt tensioner for slop. You did replace the belt with the alternator right?

Sorry about the 2nd threat but i didn't got any more responses. Yes I did replace the alternator belt. The alternator is brand new I bought it at the auto parts and installed myself. I checked the volts at the alternator bolt so I can compare and make sure that is maybe a bad wire and it was reading the same volts as the conection at the battery. The problem is when is on gear. If it is in idle with no gear it keeps the charge around 13.5-14.3. Same reading at the alternator bolt. I had a friend hit the brakes and put it in gear and i checked the voltage and it drops to 12.5 and if you wait long enough it drops to 11.9 depending on the stuff i'm runnning like the headlights , etc. I got the same reading at the alterantor bolt.

So it looks like the alternator is producing this voltage not a problem in the wiring. I also check the alternator on the autoparts website to make sure they didn't give me the wrong one and the part number is the same one on the box . This the link and i bought the 1st one on the list. http://www.partsamerica.com/ProductList.aspx?PartType=11&PTSet=A&SearchFor=Alternator

The car has never shut down or gave me any problems with this matter but I know the voltage should not be this low. I don't think the belt is loose and the belt tensioner seems ok but i haven't replace it. I don't know what else to try. It's like is the wrong alternator or something. The only other think that I notice in the car is that the idle is off alittle. When it is in gear and i release the brake pedal it takes off pretty quick. It can hold 25 MPH if I let the accelerator off while moving at slow speed. Thanks for helping guys. I know you guys will help me figure it out.

I'm happy to annouce that my problem is solved. It was a BAD alternator. A brand new one and it was bad!. Just got a different one and its charging 14.2 and maintains around 13.8 with everything on. Thanks for the helps folks.

Ok my problem is back again. I already swap 3 alternators and same result. I did noticed that the voltage drops bad when the radiator fan kicks in high. I check connections, grounds and everything else that I could think. I'm not sure if this is normal since this is my 1st T/A. I took the alternator out and took it to 2 different stores to bench test it and both said that it was good. The only think we noticed was that the radiator fan is consuming more than 30 amps, not sure if thats normal. I did replace the fan motor and no change in the voltage. I haven't check if the new one is consuming more than 30 amps also. Again it hasn't shutdown on me nor the lights are dimm, etc.

The only think i have left will be to change the battery and the wires to the alternator but im still getting the same voltage at the alternator terminal. They tell me at the auto parts store that the battery is good. Someone said that maybe the pulley on the alternator is too big but i didn't noticed any difference in the size.

The other option will be to get a bigger alternator or a new one from AC Delco but I still think it should be plenty with the factory rated one. Any other ideas? thanks.

I could ahve sworn I read that the battery was new and the wiresw were already checked :dunno:

30A doesn't sound out relm, whaat is the rating o ffuse protecting the circuit? Probably 30A.

Hi, Can someone tell me the voltage range for a 98 T/A with load (everything on)? Thanks.

The fuse is 40amps. I'm sure the fan is normal. The battery and wires haven't been changed yet. It basicly the only things left. Everytime I went to the auto parts store they checked the battery and told me it was ok. The reason I haven't change the wires is that I get the same voltage reading at the alternator terminal. But I think i'm going to change these 2 items and see. Changing the fan was good idea because the A/C one needs replacement soon. It making noise when you turn it manually. I'll change the belt tensioners tomorrow. The other thing I was thinking was the small wire that connects to the regulator area in the alternator. But looks good.

See, now here's a problem, multiple threads on the same issue. :disappoin

threads merged

I had this problem kind of, and it turned out that a cylinder in the battery was half way burnt out! Check your battery

Cylnder in a battery?

Well I took the car various times to check the charging system and in all of them they said that the battery is ok.

I also have a 1998 Formula with the identical problem. I hope you read this and have some insite because I am really frusterated at this point. I couldn't describe my problem any better then you did. I have replaced the alternator, battery, upgraded the alternaor and battery wiring and the problem persists. I have owned the car for 2 1/2 years and the problem started just this last Saturday. Can you please keep me posted on what you have tried and I will do the same. I was also goin to replace the fans, but after reading the post, decided not to. Have you had anything at all wierd happed when locking the car with the FOB, acting like it maybe setting of the panic or the security light on the dash staying on for a long period of time after the car has been started before going off. This started pretty much at the same time and I can't tell if they are related or not. Thanks and please if anyone has an idea, let us know.

Niebur3 to this point I haven't followed the problem anymore since nothing bad has happenned. The car has never shutoff or gave any problem as for the FOB problem, i don't have any with my car. We put an ampmeter in the alternator line and it was reading at least 75 amps, so to me the alternator is working. Some people told me also that the voltage is controlled by the car's computer. I'm not sure of what could it be. But like I said the alternator appears to be working and the car is running fine. I will suggest to get a second voltmeter the one that you can put in your cigarrette lighter plug and compare the reading with the cluster. I also cleaned all my cable terminals for corrosion and my grounds also and it didn't make a difference. The only thing I can say is that your FOB problem could be a different problem. I'm been trying to find another trans am drivers in my area to ask them if they had that problem but i have to catch em 1st lol. Keep posting more info if you get it resolved. I'm pretty sure others will suggest other things that you can try. Good luck!

Just put a new battery on it and no difference in the voltage. The situation is still there (not sure if I should call it a problem anymore since the car acts completly normal). I also changed the belt again and the belt tensioner is brand new. The only thing left is the wires that go to the battery. I never seen this kinda of situation before in a car. It stayed (if working properly) above 13.8v at idle in my other vehicles.

you know what, if none of your LIGHTS arent flickering (At low idle, high idle, etc) then i think theres no big problem. just carry a 'battery starter' kinda thing in the back of your trunk, one fo those porta-jumperthings.

if anything id reallythink your lights would flicker if its not gettin 12+V. its really noticeable too..park it up against a wall @ night, let the rpm drop..see if the light gets duller...then rev it a little..to like 3K or so..see if the light gets brighter

Yeah I know I think that there is no problem at all. I haven't notice any flickering or dimming on my ligthts. I'll keep an eye on it. I already have one of those battery packs on my car lol. You never know when a hot chick with a dead battery is going to need it. :grinyes: