Your alternator.
I say this because of the secondary effects it can have on the rest of your systems.
1) Cooling, this is critical, why would your alternator make a difference here? Because if its failing or putting out lower voltage guess what, your fans aren't spinning as fast as they should and you're not cooling your car which is very important due to the design of these cars (especially in summer).
2) Air Conditioning, weak A/C at idle is a symptom not only of potentially bad A/C related parts, but also of a weak alternator for the same reason as 1, if your fans aren't drawing enough air, your heat exchanger won't be working as well, leading to poor idle cooling performance.
3) TCC / ABS codes. You are far more likely to get these codes when idling a weak alternator and then hitting the gas. The sudden draw will drop voltages across the board and if it goes too low will set the low voltage code and disable your TCC and ABS, this is annoying in stop and go as it locks out 1st gear
4) Poor WOT performance. Weaker alternators can severely limit how hard you can push your car as the resulting voltage drop from a partially failed alternator can lead to higher rpm stumbles, cutoffs, "Service Charging System" message/codes, or worse, a lean condition due to too little power reaching the injectors.
5) Other PCM, TCC, RSS, etc codes. Looking through the FSMs, there's a boat load of low voltage codes that can be set w/o a DIC message that can actually alter the car's behavior w/o the driver knowing.
Long story short, go into your DIC and modify the checksum value to add battery voltage to the display and keep it up as in indication. The FSM says the voltage range on startup should be 14-16V, while driving 13-15V, and nothing about idle, from my experience a good alternator will put out somewhere close or around that range w/o too much dropoff. If you're seeing it drop to 10-11V at idle, go to AutoZone or the like and get a free alternator test. If it's weak or bad, REPLACE IMMEDIATLEY, you'll be glad you did...
I say this because of the secondary effects it can have on the rest of your systems.
1) Cooling, this is critical, why would your alternator make a difference here? Because if its failing or putting out lower voltage guess what, your fans aren't spinning as fast as they should and you're not cooling your car which is very important due to the design of these cars (especially in summer).
2) Air Conditioning, weak A/C at idle is a symptom not only of potentially bad A/C related parts, but also of a weak alternator for the same reason as 1, if your fans aren't drawing enough air, your heat exchanger won't be working as well, leading to poor idle cooling performance.
3) TCC / ABS codes. You are far more likely to get these codes when idling a weak alternator and then hitting the gas. The sudden draw will drop voltages across the board and if it goes too low will set the low voltage code and disable your TCC and ABS, this is annoying in stop and go as it locks out 1st gear
4) Poor WOT performance. Weaker alternators can severely limit how hard you can push your car as the resulting voltage drop from a partially failed alternator can lead to higher rpm stumbles, cutoffs, "Service Charging System" message/codes, or worse, a lean condition due to too little power reaching the injectors.
5) Other PCM, TCC, RSS, etc codes. Looking through the FSMs, there's a boat load of low voltage codes that can be set w/o a DIC message that can actually alter the car's behavior w/o the driver knowing.
Long story short, go into your DIC and modify the checksum value to add battery voltage to the display and keep it up as in indication. The FSM says the voltage range on startup should be 14-16V, while driving 13-15V, and nothing about idle, from my experience a good alternator will put out somewhere close or around that range w/o too much dropoff. If you're seeing it drop to 10-11V at idle, go to AutoZone or the like and get a free alternator test. If it's weak or bad, REPLACE IMMEDIATLEY, you'll be glad you did...
