Alternator Working Intermittently

[terigt01]

I have a 06 GT and I'm getting the check charging system. Where do I start? Do anyone know a good mobile mechanic in Jacksonville, fl?

 

[DieHarder]

How old is the alternator? Got a VOM (Volt/Ohm Meter)? If not, go get one. You'll need it. If you have one check the DC voltage across the battery terminals. What is it? If lower than 14v alternator has gone south or you have a bad engine ground.

If you don't have a VOM I'd start by removing connections at the battery and alternator; cleaning them and the main grounds. Hook everything back up and check whether the idiot light has gone out.

If not, check if you have a bad engine ground by using a pair of jumper cables (connect the negative lead only to a mounting bolt for the alternator and the other negative lead to the ground on the passenger strut tower). If the idiot light goes out you have a bad engine ground. To fix it add a permanent 4 gauge cable from the alternator mounting bolt to the ground at the passenger strut tower.

If neither has any affect time to remove the alternator and get it tested.

 

[Autokyrios]

I have a 06 GT and I'm getting the check charging system. Where do I start? Do anyone know a good mobile mechanic in Jacksonville, fl?

Take it to an auto-parts store (advance, zone, o'reilly, etc) and they'll test it.

If the battery is original, replace it. Don't burn brain-cells over it.
If it's newer, again have it tested, but if you have doubts/concerns, replace it.

Same sort of deal with the alternator.

A bad ground can cause issues like this, too.

If you're concerned about a parts place and don't have a trusted shop, take it to a dealership for a diagnosis. They have machines for testing batteries and alternators that'll do more than regular testers. Not saying the dealership's aren't scammy, too, but it's a fairly routine issue and at 18-years it's probably time for new bits anyway.

 

[thump_rrr]

I have a Saleen supercharger on mine so the alternator is flipped around backwards and the clutch pulley is removed for obvious reasons. Since it spins in reverse the cooling fan in the alternator isn't doing much.
I've fried several alternators on long trips so I have been carrying a spare alternator and tool kit with me the last 15 years.
the last alternator started giving me the check charging system message so I opened it up and the regulator fasteners were loose. I tightened them up and haven't had a problem since.

 

[ReddComett]

What did it cost to rebuild?

From Memory, Approximately the same as a decent new aftermarket unit.

In my Experience, you can tell if your Aftermarket Alternator is good with the following technique: on various websites, they sell a a 12v socket charger which shows the voltage output of the Alternator. If you have just started the car cold after some time, the voltage should be 14 volts, or more. If it is not, you have received a unit that has been poorly refurbished with an incorrect regulator, which will only bring your system to about 13.8v at max. (I state this as fact, but this is my experience on this, went through 2 alternators before having the original fixed. I didn't get cheap ones, either.)

Later on in the electrical saga I've had with my car, I also found there to be an issue with my custom radio setup, for public information, but with this info, you can save yourself from eating alternators just by having it rebuilt. It's been happy for several months now.

 

[86GT351]

I have a Saleen supercharger on mine so the alternator is flipped around backwards and the clutch pulley is removed for obvious reasons. Since it spins in reverse the cooling fan in the alternator isn't doing much.
I've fried several alternators on long trips so I have been carrying a spare alternator and tool kit with me the last 15 years.
the last alternator started giving me the check charging system message so I opened it up and the regulator fasteners were loose. I tightened them up and haven't had a problem since.

This has been a long running issue. Due to the reverse rotation. department of Boost has a viable option for the S197 cars

 

[86GT351]

From Memory, Approximately the same as a decent new aftermarket unit.

In my Experience, you can tell if your Aftermarket Alternator is good with the following technique: on various websites, they sell a a 12v socket charger which shows the voltage output of the Alternator. If you have just started the car cold after some time, the voltage should be 14 volts, or more. If it is not, you have received a unit that has been poorly refurbished with an incorrect regulator, which will only bring your system to about 13.8v at max. (I state this as fact, but this is my experience on this, went through 2 alternators before having the original fixed. I didn't get cheap ones, either.)

Later on in the electrical saga I've had with my car, I also found there to be an issue with my custom radio setup, for public information, but with this info, you can save yourself from eating alternators just by having it rebuilt. It's been happy for several months now.

There is more testing to be done to verify proper function. What about Amp output? Just as important as Voltage!