Odd voltage readins

[quest49s]

I have been getting odd voltage readings lately and am pretty sure it is the voltage regulator inside the alternator, but wanted to throw this out there to see if there are any other possibe answers.

My car is a U.S. 91' Talon Tsi so it doesn't have the 90amp alt. like the canadian one. I statred my car this morning and my volts are at 16+ volts. If I turn on the headlights, heater and rear defroster, the voltage drops down near 13.5~14.5v. If I turn all three off at the same time the voltage will stay in the area for around 5-10 seconds, then sharply shoot up to 16+ volts again. I imagine it is safe to drive if I have all the accesories on and am keeping the voltage down below 15 or so volts, not permenatly though just til I can get an alternator.

Thanks,
Jon

 

[blackbyrd]

Sounds like a regulator problem to me. Be careful, 16+v to the battery is a lot. Average is 14.5 I believe.
You can take it to autozone/advanced auto to verify if it's bad, but whatever you do please don't buy theres!

 

[DGajre777]

Mine does exactly the opposite, it goes from 11v to 13.9v max. I was told it was a possible bad diode inside my rectifier inside my alternator.

 

[generalu]

I've been having the same problem. There have been occasions where all the electronic components would die for a split second while driving on the freeway. So I replaced both my battery and alternator (135amp) - and from what I recall, the stalling hasn't happened again. When the engine's cold, I get solid 13.5-14v readings, but after warm up, voltage drops down to about ~12v when I brake to idle, then back up to 12.6-13.1v at idle. In the evenings at idle, with my HID's on, brake lights one, and blinker on, the voltage readings sometimes drop down/below ~11v. Either the past and current alternator's have both been bad, or there's another problem. My ignition fuse recently blew out while driving down the freeway (not fun at all) - and now I'm looking all over the place for a possible short/problem. I would get your alternator checked out first - luckily your cars up and running even with such high voltage readings. Please post what you find out. Good luck.

 

[DGajre777]

I wonder if over voltage and under voltage are both related to each other and are caused by the same part. One thing I did was took out a blown fuse out (cig lighter) and took out the fuse and relay for the fog lights (since I had taken them out). I used to get the battery and brake light once in a while when I start my car, but it hasn't come yet. I'll hopefully take my car to get it check sometime this week to find out for sure if the alternator is bad or if I have a short somewhere.

I do know that over voltage is a bad voltage regulator, but I'm not sure why voltage would drop to 11.0v when the car is running (this was audio system on, A/C on, and headlights on). This is what my car does - http://www.dsmtuners.com/forums/showthread.php?t=242491. Don't know if it is related, but try all the things that other members have mentioned in the thread linked above.

 

[quest49s]

Ok i replaced the alternator the other day and everything is running perfectly again

 

[blackbyrd]

Good! Where did you end up getting your alternator at?

 

[quest49s]

I got a remaned one from Napa w/ a 3 year warrenty for $140 something