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By LazyPrizm, July 16, 2013

Hello, Corolland! This is my first HOWTO, and I hope it is as helpful to someone as many, many of the discussions and guides on this site have been to me. See the post after the instructions for some information on diagnosing a failing alternator, and an explanation for why there's actually three alternators photographed throughout this guide :-)

CAR: 98-02 Prizm/Corolla, but should apply to any generation with the 1ZZ-FE engine

TIME: 2hrs first time, 1hr the next time

DIFFICULTY: Easy for a shade tree mechanic

PART NUMBERS: 27060-0D010-84 (Toyota, reman.) or 210-0432 (Denso, reman.)

COST: $120-215, more for new alternator, less for other brands

0. Tools

Breaker bar / pipe (optional, makes removal much easier)

8mm, 10mm, 12mm, 14mm, 19mm sockets (6-point may be better than 12-point)

Socket wrench

Torque wrench w/ ft-lbs (optional, but a good idea)

Needle nose pliers (optional)

12V battery trickle charger (optional)

Haynes/Chilton/Factory repair manual (good for diagrams)

1. Recharge the car battery

A dead car battery that has been frequently jumped, and run connected to a failing alternator is likely to be low on charge. You don't want the replacement alternator to be immediately put to the punishing task of recharging the battery -- so charge it first. I used a $20 12V/1.5 battery maintainer, run overnight. If you have a way of getting the battery to an Advance Auto, they offer 30 minute quick charging.

If you have a multimeter, the battery should read 12.4V (or higher if the surface charge is not removed). See post #2 for

a link to all the car battery information you could ever need.

2. Disconnect the battery (if still in car)

Before starting any repairs, disconnect the negative battery terminal with the car in Park and the parking brake set. Wear eye and hand protection while working under the hood! If you have an aftermarket stereo or alarm, make sure you have read the manual and know how to return them to service once the battery is reconnected. Disconnect the positive terminal. I like to put a small towel over the battery to make sure nothing accidentally touches the terminals.

3. Remove the plastic engine cover

Unscrew the two 10mm nuts on the front of the plastic engine cover, and unhook the fasteners at the rear. I snapped mine off long ago and have no regrets about doing so.

4. Caution for Prizm owners, move fuse/relay block

Geo/Chevrolet Prizm owners will find the A/C accumulator unhelpfully located next to the alternator. Be very careful while following these procedures not to dent or puncture and of the A/C hoses or tubes run through this area.

Unscrew the two 10mm bolts holding the front fuse/relay block. This will give you more room to work on the lower bolt. Once the alternator power cables are disconnected, you'll be able to move this box out of the hood compartment.


5. Release tension on the drive belt, remove belt from alternator pulley

Locate the 19mm "fake nut" on the tensioner. This nut will not rotate, but you can use it to release tension on the belt. Using a long wrench or breaker bar, apply gently pressure down on the nut. The tensioner should smoothly (but slowly) release slack in the belt. It may help to use a segment of pipe or another wrench to increase your leverage here.

The nut as viewed from above, standing on the passenger side of the engine compartment looking down. If the tensioner will not move, does not return to the original position, or makes grinding noises, you may want to consider replacing it as well. Try to only remove the belt from around the alternator with as little impact to the rest of the belt winding. This will make re-assembly much easier.

6. Disconnect the electrical connections to the alternator

Depress the plastic clip and release the alternator connector, (1) in the pic above.

Peel back the boot on the alternator wire, and remove the 10mm nut holding it in place.

Pull the alternator wire off the clip on the front of the alternator. You will now be able to move the fuse block from Step 3 out of the way.

7. Unhook alternator connector wires from back of alternator

If you are able, use the needle nose pliers to pinch and remove the fastener holding the connector wires to the rear cover of the alternator. If you can't get it at this point, don't worry yet.


8. Remove the alternator bolts

This is the finger bashing step. My alternator was screwed down *very* tight, and I needed to use the breaker bar and a pipe to loosen the bolts. Be careful if using 12-point sockets, which are more prone to damaging bolt heads. Start with the lower bolt, which takes a 14mm socket. Next, remove the upper bolt with a 12mm socket. Be prepared to hold the alternator if it comes loose after removing both bolts, although odds are it will still be tightly in place. Gently rock it loose if needed.

You can see some damage my 12-point socket did to the lower bolt's head. This made it a real pain to get back in with the torque wrench, so I ordered a new one from Toyota. The part number is 90105-10075, "Alternator mount bolt".

Pull the alternator out as far as the cable will allow you (if Step 7 was unsuccessful). Use an 8mm socket to remove all the bolts from the back cover. One of the bolts may need a Philips head if your socket is unable to fit around it. Remove the body of the alternator from the car.

It should now be easy to release the connector wire's fastener. Re-attach the back cover if you will be returning the alternator core.

9. Examine the new and old alternators

This picture shows the original 11 year/160,000 miles old Toyota Denso alternator (made in Tennessee!) and a Remy (re-branded by Advance Auto) remanufactured unit from Mexico. Note that the Remy includes the 10mm nut for the wire connection, but does not include the clip. If you need to order a new clip because yours is rusty like mine, the part number is 27446-22030, "Clip, cord".

Here we have a Denso remanufactured alternator, ordered through Advance Auto's website. It comes with the clip, but not with the 10mm nut. So check what hardware you will need to save from the old one!


10. Install the new alternator

Slide the new alternator into position. To make lining things up easier, start screwing in the upper bolt by hand. Once it is in enough to support the alternator, you can insert the lower bolt, while adjusting the position of the alternator until both bolts can be threaded. Go slow with the socket wrench, make sure not to damage any threads. Back out and try again if it feels like things aren't catching.

11. Torque down the bolts

Set your torque wrench to 40 ft-lbs, and use the 14mm socket to tighten the lower bolt. This may be slow and tedious work, I only had room in the Prizm to do a few clicks at a time.

With the torque wrench set to 18 ft-lbs, tighten the upper bolt.

12. Loop belt around alternator pulley

Repeating the earlier process with the belt tensioner, use the breaker bar and 19mm socket to release tension on the belt. Hold on to the belt with one hand to make sure it doesn't slip off any other pulleys.

Pull the belt over the alternator pulley, making sure the grooves line up. Check the belt routing diagram in the manual (or google for one, there are many posted including on this site). Make sure the belt is centered on all pulleys and that the smooth side of the belt is in contact with smooth pulleys, and the grooved side of the belt with grooved pulleys. Release the tensioner.


13. Replace fuse/relay block

Using the 10mm socket, re-attach the fuse/relay block.

14. Connect new alternator

Plug the alternator connector in to the socket on the rear of the new alternator. Attach the alternator wire and secure it in place with the 10mm nut. Move the rubber boot completely over the end of the wire and bolt. Re-attach the wire clip. I don't recommend re-attaching the fastener on the connector yet, as it may be hard to remove if your new alternator is a dud.

15. Reconnect battery, start

Reconnect the positive battery terminal, then the negative terminal. Make sure both connections are secure. Start the car! If the alternator/battery service light does not come on, check the voltage if you have a multimeter. It should read 13.5-14.8 volts. The Haynes manual lists upper safe voltage as 15.1V, the Denso manual lists 14.8. Voltage above the desired range can indicate a problem with the relay.

After the engine has been running for a while, you can stress test the new alternator. Turn on the high beams, turns the A/C on high and coldest, and turn on the rear window defroster. You should see the voltage drop, then return the the desired range.

If you car has a throttle cable, you can rev the engine (or have an assistant apply the gas). The voltage may go up, but remain in the correct range. Turn off the defroster when you are done testing to avoid damaging the heating element.

When you're satisfied that everything is working, replace the engine cover, tighten down with the 10mm nuts, and check that you aren't left with any "extra" parts.



0. Briefly, the alternator and the battery

Your car battery's primary task is to hold power in reserve to crank the starter. Its secondary task is to prevent damage to car electronics while the alternator is running (so don't operate a modern car with the battery disconnected!). Starting the car puts a large strain on the battery's power reserves.

The alternator's primary task is to keep the car electrical systems running, by acting as a generator powered by the engine. This includes the headlights, stereo, power steering, fuel injection and ignition. The more power the car needs to run, the harder the alternator must work. Alternators are rated by amperage (our Corolla/Prizms use 80A alternators). Any power not being used to operate the car is used to recharge the battery for the next start.

Obviously, if the alternator is weakening, less power is available. The headlights may dim when the A/C is on; less power is available to recharge the battery. On a short trip, the battery may not even fully recharge. After many short trips, the battery may no longer have enough power to start the car, and you will need a jump start. Eventually the alternator may die, which will leave the car inoperable once the battery is drained.

Keeping this in mind, if you find yourself needing a jump start, consider using an indoors trickle charger, or having a car parts store recharge your battery afterwards. This will extend the life of your battery and your alternator.

1. Diagnosing a failing or dead alternator

It can sometimes be difficult to determine if your alternator, battery or starter are at fault. Roughly, symptoms of a bad

alternator include:

  • Car needs jump-start in the morning or after short trips
  • Car cranks one time without starting, but cannot be cranked a second time
  • Car suddenly loses power while driving
  • Turning on one accessory (high beams, A/C, defroster, window motor) causes interior or headlights to dim
  • -BUT- the car always starts when jumped

If your car cannot be jump started, the problem is likely to be either bad battery connections or the starter. In the worst case, you might have several things go wrong! In my car, the positive battery terminal was badly corroded. This part is easy to replace, and can be ordered from Toyota, part number 90982-05035 (Terminal).

A multimeter is your best friend when doing diagnostics. Cheap ones can be ordered online or found at Radio Shack. Read reviews to make sure you are getting a good one. Make sure it has a usable DC voltage range (ie, 20V). Start with a known charged battery (use a trickle charger or a store that offers a free quick battery charge), and check the voltage between the terminals. A good battery should read above 12.4V with the engine off.

Start the engine and check the voltage. It should read between 13.5-15.1 volts. Rev the engine, and see if the voltage increases. If the voltage exceeds these limits, the alternator's regulator may be faulty. Try turning on high beams, the A/C and the defroster. If the voltage is low, the alternator is weak. If the voltage is in the proper range, peel back the boot of the alternator wire, and run one of the multimeter probes. If the voltage is very different than between the battery terminals, it may just be a bad wire or terminal.

For example, on my car, the voltage was 13.84V on start, but dropped to 12.35 when all accessories were turned on. Revving the engine only increased voltage to 12.89V, still too low for safe operation, much less to recharge the battery.

2. Alternator alternatives

I'm a cheap guy, and lazy to boot. With most repairs, I'm happy to use whatever part saves me the most time and money, and is of a sufficient quality to not need replacement for a reasonable amount of time or cost. So I normally avoid buying Toyota/AC Delco parts if there is a good alternative available.

You'll find much debate online about the quality of various alternator remanufacturers. Many people recommend finding a local alternator shop to do the job. This may be a good option if you can spare the time without your car for the work to be done. The local shop will usually offer a short warranty to ensure the unit at least works.

Your next choice is to buy a remanufactured unit with a core charge. BBB Industries, Remy, Denso and Bosch all sell remanufactured alternators, under their own names as well as other brands. Advance Auto store brand are Remy units, NAPA and CarQuest use BBB (though this may vary from store to store). Warranties vary, from 1 year on the Denso, 3 on some BBBs, to lifetime on certain Remy and BBB units. That said, the quality can vary immensely, and may not correlate to the length of the warranty. BBB and Remy units remanufactured in Mexico can be of debatable quality, with stories traded online of units failing after weeks or operating fine for many tens of thousands of miles. This may be somewhat mitigated by the good warranties you can find on these units, at least if you are confident in doing the replacement, and live near one of the stores where you can obtain replacements.

Bosch and Denso are more highly regarded, but cost accordingly more. Some Advance Autos (and possibly other stores) have the equipment to test an alternator in the store (this is different from the in-car test). This free service is worth considering if you buy a store-brand unit.

In my case, the Remy unit I bought first failed immediately -- no power. I returned it for a full refund at AAP, and ordered a Denso from their site, which so far (knock on wood) is working perfectly. The Denso was remanufactured in a US facility. It's a shame I found out about the alternator bench testing after I installed, removed and replaced the Remy unit! (on the up side, I can replace my alternator in no time flat) ;-)

Here are the costs for the alternators I looked at:

Toyota reman, from Mid-Atlantic Toyota: $214 + s/h & core (1yr warranty) (possibly a Denso?)

Denso reman, from Advance Auto + discount code: $157 + core (1yr warranty)

Advance Auto ToughOne (Remy) reman, + discount: $90 (lifetime warranty)

AC Delco reman, from RockAuto: $147 + s/h & core (1yr warranty)

NAPA Rayloc (BBB) reman: $125 + core (3yr warranty)

You'll have to determine where the balance between cost, reputation/quality, and warranty meet for your needs.

3. Further reading

Car and deep cycle battery FAQ:

Paul's Corolla guides (9th gen, but very easy to adapt for 8th)

Remy charging system troubleshooting guide:

4. Thanks

First, I'd like to thank FishExpo for running Corolland. Forum gurus dshadle1, Dom, (Fish, again), Paul from (whatever your user name is), and everyone I'm forgetting -- thanks! I've been a reader of the site and forums for a long time now, and have learned an immense amount from the discussions here. This HOWTO is an attempt to in some small way give back to the community for all the help I've gotten. I hope it's useful to someone, and as expected, I am not liable for any damage you or your vehicle suffer for following these crude instructions ;-)



Great DIY Guide! Nice clear pics and directions - definitely easy to follow. Should help a number of members and others looking to tackle this job.

Thanks for taking the time to document your experience and sharing with us!

Hey new to the forum. Just wanted to register and ask a question since my knowledge with cars is very poor. I understand the whole process but I cannot find this "fake nut" from my car... Which is used to release the tension. I removed the old dead alternator but I cant find the nut to tighten the belt. My car is Toyota Corolla 1998 with 1.6 benzine engine

Welcome to the forum.

The instructions posted above are specific to the 1.8L 1ZZ-FE engine - this case on an 8th gen Corolla (model years 1998-2002). The fake nut is used to take pressure off the serpentine belt.

Assuming that you have a 1.6L engine - sounds like yours might be the 1.6L 4A-FE/4A-GE - totally different setup.

Since you didn't mention where you are located, I'm assuming it could be a European, Asian, or Oceanian market Corolla - as those markets still used the 1.6L engines (actually run from 1.3L to 2.2L engines). North American market only got the 1.8L engine.

In your case, there is no belt tensioner - just separate v-belts. You take pressure off the belt by loosening the bolts on the alternator bracket. Process is identical to our North American 7th gen models (1993-1997) with the 1.6L 4A-FE and the 1.8L 7A-FE.

Topic List: Go to Toyota Corolla, Chevy Prizm (1998-2008)