1996 Saturn SL2 Alternator

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Last week my wife told me that a ‘Charge Battery’ light on the dashboard of her car (1996 Saturn) came on (and stayed on). When I looked at the user manual, it was clear that the problem was probably with the battery, the alternator, the regulator, or the wiring that connects these parts together. Although the vehicle is 1996 Saturn SL2 sedan, the information provided here may be applicable to most other vehicles. I wanted to document what I learned here so that I can remember it later.

Battery

I drove my son to his school early Saturday morning, and on the way back I noticed that the tachometer showed 0 RPM, which was wrong. Moments later the speedometer also showed 0. It seemed like the indicators were randomly showing bogus values. The engine also started to run rough when I made it to home and parked the car in the garage.

The first thing I did was to check the battery and noticed that the battery was over 5 years old. Whether the battery was still good or not, I thought the battery should be replaced to eliminate that possibility. I bought a new battery and replaced it.

But the car would not even crank now.

Taking the old Alternator out

In Saturn’s, the regulator is built into the alternator. We called up the junk yard parts store and bought an alternator (pulled out from a scrapped Saturn).

If a single word should be chosen to describe replacing the alternator in Saturn, that word would undoubtedly be ‘Hell’. This was partly due to the ‘learning process’. Once you know how to do something, it is of course so much easier the next time. But the difficulty was also due to the location of the alternator and access to it in Saturn’s.

1996 Saturn alternator1996 Saturn alternator

It is hard to see it, but in the picture above the alternator is the lower pulley with the fins in the middle below the big pulley at the top left of the picture.

Tensioner pulleyTensioner pulley.

In this picture the small pulley at the top of the picture is the tensioner pulley.

To replace the alternator, you have to jack up the front right side of the car, and take the right wheel off. Then take the two covers in the wheel well: the middle one and the one to the right of it as you face it. These covers are kept in place by plastic grommets. You can use needle nose pliers to take them off.

Wheel wellWheel Well

Looking into the wheel well. The large pulley in the middle is connected to the engine shaft.

Taking the serpentine belt out

The next step is to take the serpentine belt out. If you (like me) don’t know how to do this, you could spend hours and get nowhere. But it is super easy when it is done the right way.

Googling the procedure was saying that you have to tighten the bolt on the tensioner pulley to release the belt. How could tightening the bolt loosen the belt? This did not make sense to me at all. But when I loosened the bolt to the point that it was completely off, the belt was still as tight as it was before.

Tensioner pulleyTensioner pulley.

In this picture the small pulley at the top of the picture is the tensioner pulley.

Tensioner pulley diagramTensioner pulley diagram.

The picture is worth a thousand words. The diagram above shows how the tensioner pulley works. Once the bolt is as tight as possible by turning the bolt in the clockwise direction (shown as A above), it can not turn any more. If you try to tighten it more, the whole tensioner arm starts to turn clockwise (shown as B above).

This second motion releases the serpentine belt. Without this second motion, the belt is so tight that it really is impossible to take it out, and even harder to put it back on.

The Alternator

Two bolts attach the alternator to the engine block. Once the bolts are taken out, the alternator will be free to move, however there are two other connections to take care of. One of them comes from the battery (thick red cable). Loosen the nut and take the ring connector out. The second one is a connector with a lock on it, you need to press on the tab to take it off.

Now the alternator is completely loose and that was the easy part. There really is not a lot of space around it to take it out. As you move it around, it gets stuck against the other parts. Since you can barely reach this part, it is not possible to put a lot of force on it. After several hour of this silliness, I realized that there was a plastic shroud around the alternator. But I could not see the bolt that attached it. I finally found the bolt by feeling it, and eventually took the bolt out. Here is the pictures of it.

AlternatorAlternator.

Alternator and shroudAlternator and shroud.

Alternator and shroudAlternator and shroud.

After I took the protective plastic shroud, the alternator fit through the small opening by the wheel well.

Putting the new alternator was easier, because I did not keep the plastic shroud that caused so much trouble. Note that there is another smaller plastic protective cover over the alternator windings. Obviously there is a trade-off here: ease of replacing the alternator, versus its lifetime.

How to test the new alternator

How do we know if the new alternator is any good? This is fairly easy to do. First measure the voltage across the battery while the engine is not running. It should be little over 12 volts as seen in the picture below.

VoltageBattery voltage when 1996 Saturn off

Then measure the voltage again while the engine is running. It should be 13 to 15 volts, but not over 15 volts. If it is over 15 volts, perhaps the regulator is bad. If the voltage is less than 12 volts, the battery is going bad, need to replace it.

VoltageBattery voltage when 1996 Saturn engine running

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One Response to 1996 Saturn SL2 Alternator

  1. Nix says:

    Just like to say thanks for the time you put into writing this and taking pictures. It’s saved me a lot of trouble and money.

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