Installing an Alternator

[Jbird06410]

Alternator went last night on my 2000 STS Seville. We bought the new alternator. Our mechanic wanted $500 to install it. We have no $500 Sooooo we ( we meaning husband while I read the manual and browse alldata and this forum with bandaides at the ready.) will be installing it ourselves. Any advice on the installation? Any surprises awaiting us?

[scott y]

I haven't done a 2000+ yet but I had my '94 done in roughly 2hrs. Mostly since I usually clean parts,bolts,etc when re&reing. However,a very straight forward job if properly equipped toolwise...best o luck!!

[BodybyFisher]

The radiator does not need to come out, put a 1/4" piece of plywood in front of the radiator to protect it

There is an inspection cover in the wheel well that you take off to gain access. Take the tire off, use safety jacks and use the parking brake.

Disconnect the negative battery cable for safety

Use ONLY an AC DELCO aftermarket rebuilt alternators do not play well with the PCM, unless its an AC DELCO NEW or ACDELCO REBUILT

[Jan Olsson]

It will be a little bit more work for you to do than when you have to replace an "ordinary" alternator since youre alternator is water cooled.

According to my FSM (factory service manual) you'll have to remove the cooling fans in order to reach the alternator.

The older STS (1992-1997 generation) was easier since you'll only had to remove the inspection cover BodybyFisher mentioned.

[Jbird06410]

We bought a brand new AC Delco Alternator -

Eric just finished installing it however we still are getting the same message - Service Charging system and the voltage is around 12 when it is usually 14. We have a code P0622 Generator F-Terminal Circuit Any idea?

thanks in advance!

[BodybyFisher]

DTC P0622 Generator F-Terminal Circuit

The PCM uses the F-terminal circuit to monitor the duty cycle of the field circuit. The F-terminal connects to the high side of the field winding in the generator. A pulse width modulated (PWM) high side driver in the voltage regulator turns the field winding ON and OFF. The PCM uses the PWM signal input to determine the generator load on the engine. This allows the PCM to adjust the idle speed to compensate for high electrical loads.

The PCM monitors the state of the F-terminal circuit. When the key is in the RUN position and the engine is OFF, the PCM should detect a duty cycle near 0 percent. However, when the engine is running, the duty cycle should be between 5 percent and 100 percent. The PCM monitors the PWM signal using a key ON test and a RUN test. During the tests, if the PCM detects an out of range PWM signal, DTC P0622 will set. When the DTC sets, the PCM will send a class 2 serial data message to illuminate the appropriate telltales.

The PCM uses the L-terminal circuit to apply a voltage to the voltage regulator. This signals the voltage regulator to turn the field circuit ON and OFF. Therefore, if an L-terminal circuit conditions exists that causes the voltage regulator to improperly control the generator field, DTC P0622 will set. DTC P0621 may also set

Check the connections at the PCM and Generator again along with PCM grounds

[Captain Rob]

The radiator does not need to come out, put a 1/4" piece of plywood in front of the radiator to protect it

There is an inspection cover in the wheel well that you take off to gain access. Take the tire off, use safety jacks and use the parking brake.

Disconnect the negative battery cable for safety

Use ONLY an AC DELCO aftermarket rebuilt alternators do not play well with the PCM, unless its an AC DELCO NEW or ACDELCO REBUILT

I have a 99 STS w/108,000 showing all the signs of alternator replacement, is this true, in my 98 service manual, it says to remove the air condition condenser and radiator. Can you be more details? This sounds to good to be true.