1999 – 2003 Toyota Prius Installation Instructions

(Click on below image for larger photo)

Time Required: Approx 2.5 hours

Tools Required:
8mm, 10mm, 12mm sockets
Wire cutters, wire strippers, wire crimping tool
Zip tie cutters, scissors
#2 phillips screwdriver, #0 phillips screwdriver
(Recommended:) Volt meter, trim panel removal tool

1) Begin by removing the rear seat bottom.

Lift on the front edge of the seat to release the retaining clips.

Push the seat belt buckles through the seat bottom and remove the seat.

2) Remove the rear seat headrests, if equipped.

Remove the three 10mm bolts holding the rear seat back in place.

Pull straight up on the rear seat back to clear the three upper alignment tabs and remove the rear seat back.

3) Remove the four 10mm bolts holding the seat back support bars and remove the seat back support bars.

Remove the five trunk trim panel clips and remove the trunk trim panel.

4) This is what the rear seat area should look like at this point.

5) Remove the trunk carpet and trunk base sub-panel.

Remove the three clips holding the 12v accessory battery cover and remove the 12v accessory battery cover.

6) Disconnect the 12V auxiliary battery ground as shown.

7) Remove the three battery cover carpet clips.

Remove the battery cover carpet.

8) Remove the two left side carpet trim clips indicated in the photo.

9) Fold the left side carpet trim back as shown. It does not need to be fully removed.

10) Remove the hybrid battery main disconnect.

11) Remove the two right side carpet trim clips indicated in the photo.

12) Fold the right side carpet trim back as shown. It does not need to be fully removed.

13) Unclip the white battery vent tube retainer (red square) by lifting it on top and rotating it out and down to the side of the hybrid battery. The next step shows the proper location when removed.

Remove the seven 12mm bolts circled and remove the right side battery brace.

Remove the two 10mm bolts circled in red and set aside.

14) This image shows the correct position of the battery vent tube retainer once removed

15) Removed the six 10mm exhaust duct vent bolts as shown.

16) Position the exhaust vent duct out of the way as shown. If the duct resists movement, you can try unclipping some or all of the wire harnesses that are attached to the underside of the duct to increase flexibility.

17) Begin the removal of the HV battery cables by removing the access cover lock. Do this by rotating the inner part of the access lock (1) with a small screw driver. Every 90 degrees the access lock will release. Rotate the inner lock in either direction while gently pulling on the outer lock ring (2). Once the lock releases, remove the lock assembly.

18) Remove the three 10mm bolts holding the HV cable cover and remove the cover.

19) On rare occasions, the battery might still have some voltage present due to a module electrolyte leak. (This is why Toyota’s service procedure requires the use of insulating gloves when working on the traction battery.)

We strongly recommend you check the battery voltage at the connection points before completing this step. Voltage should be less than 1V. Use only one hand to remove the 10mm bolts. Do one wire at a time. NEVER touch both battery terminals at the same time.

Carefully remove the 10mm HV connection bolts circles in the photo. These are very special bolts and must not be mixed with any of the other bolts. Pay special note of where you place them to be sure to reinstall these same two bolts.

Note the orientation of the HV cable retainer located behind the wires (circled with a oval in the photo), it is common for this to fall off while the battery brace is removed from the car and reorienting it properly is important.

20) Once the HV cables are disconnected, they can be pushed out of the way as shown. This is another few of the HV cable retainer showing the proper orientation.

21) Remove the seven 12mm bolts circled and remove the left side battery brace.

22) Remove the two 10mm bolts circled and set aside.

23) From the rear of the vehicle, remove the five 12mm and two 10mm bolts circled.

24) Return to the rear seat area and remove the five 12mm and one 10mm bolts as shown.

25) The battery cover can now be removed by lifting up on the left side, then sliding the cover to the left approx one inch. This must be done to clear the right side exhaust duct bolt bracket.

26) Remove the white terminal cover by lifting up on the front and once vertical releasing the rear tabs.

27) Position the car harness in the left side of the trunk area roughly as shown.

28) Route the red charge positive and black charge negative wires into the HV battery through the large passage noted with the red arrow.

29) Again a reminder: On rare occasions, the battery might still have some voltage present due to a module electrolyte leak. (This is why Toyota’s service procedure requires the use of insulating gloves when working on the traction battery.)

We strongly recommend you check the battery voltage at the connection points before completing this step. Voltage should be less than 1V. Use only one hand to make the connections. Do one wire at a time. NEVER touch both battery terminals at the same time.

Connect the red charge positive and black charge negative wires to the 8mm high voltage battery posts as shown. Note the black charge negative connection wire may have to be bent upwards slightly to allow the HV battery 8mm bolt to be properly tightened. This is normal and should not be cause for concern.

Reinstall the white plastic terminal cover (not shown).

30) Reinstall the battery cover by sliding the right side under the exhaust duct bolt bracket then settle the cover into place. We will not be reinstalling any of the hardware yet, just set it in place for now.

31) By hand, squeeze the external vent tube spring clip and slide it up the vent tube and away from the hybrid battery cooling fan.

32) Remove the three 10mm bolts holding the hybrid battery cooling fan in place and remove the fan.

Note the depth that the fan penetrates the internal exhaust tube. You want to make sure it is fully reinstalled later.

33) Rotate the fan as shown and unplug the fan wire harness and fan wire harness clip circled in red.

34) Cut the hybrid battery cooling fan wire harness in the location shown.

35) Strip the wires back approx 1/4″ and twist the like colored wires together.

Crimp the provided spade terminal onto the combined wire ends.

Repeat process for vehicle side of fan wires.

The wire harness retaining clip can be removed. It will not be reused.

36) Repeat process for vehicle side of fan wires. Cut the wire insulation back approx four inches on the vehicle side of wire harness and discard.

OPTIONAL BUT RECOMMENDED:
37) We highly recommend taking a few extra minutes to clean the hybrid battery cooling fan. The fan has no filter on the intake duct and often becomes clogged with debris. This contributes heavily to hybrid battery overheat and premature failure.

Carefully clean the fan vanes with a towel, old toothbrush, and any other item needed to complete the task. The image at left is of a fan with very light debris buildup. They can be much worse than this.

38) Refer to the enclosed wire connection card or the diagram at left to determine proper wire connection points.

39) Install the fan side wires on the hybrid battery cooling fan control before the vehicle side wires to make the process easier.

Install the vehicle side wires on the hybrid battery cooling fan control sub-assembly as shown.

40) Carefully align the wires in the hybrid battery cooling fan control sub-assembly enclosure passages and install the enclosure cover using the provided mini-Phillips screws.

Some resistance when tightening is expected, this is an anti-tension mechanism that is designed into the enclosure.

41) Plug the hybrid battery cooling fan wire harness back into the fan itself.

Reinstall the fan with the three 10mm bolts previously removed.

Reinstall the external vent tube and external vent tube spring clip.

42) IMPORTANT – Test the charger before re-assembling the vehicle. We recommend that you connect the charger to the car harness before plugging it into the wall and unplug it from the wall before disconnecting it from the car.

To perform the initial function test: First, make sure all fingers and tools are clear of all wiring and hybrid battery components. Plug the charger into the car harness. With the hybrid battery main disconnect still removed, plug the charger into the wall. After a few seconds, it should read approx 340 volts on the meter and both the charger and hybrid battery cooling fans should be running. You should also feel the hybrid battery cooling fan control enclosure vibrating as its internal cooling fan is also running.

Note in the image at left the hybrid battery main disconnect is not present and the charger is displaying max voltage.

43) Next, carefully connect hybrid battery main disconnect. One the disconnect is reinstalled, be sure to lock the release ring/handle up and in place to make a good connection.

You should see the charger voltage drop as the charger voltage equalizes with the voltage level of the battery pack. This should happen quickly. The voltage level should be stable and not fluctuating. All fans should still be running.

Note in the image at left the hybrid battery main disconnect is present and the charger is displaying battery voltage.

If anything is wrong, stop and contact us. If the fan is ‘pulsing’ (powering on and off) every few seconds, stop and contact us.

This completes the test. Unplug the charger from the AC power source and disconnect the charger from the car harness. If the test was successful, you can leave the hybrid battery main disconnect in place.

44) Secure the wire harness with the provided zip ties as shown.

Note the large zip tie goes around the trunk body support. A second small zip tie behind the body panel (not shown) secures the hybrid battery cooling fan enclosure to the large zip tie. Only tighten this until snug. Do not over tighten. This second attachment point is to prevent rattling of the enclosure against the vehicle frame. If over tightened, this may cause the fan wire harness plug to ‘pull out’ from the fan.

45) Using the remaining large zip tie provided, secure the car harness to the 12V auxiliary battery brace as shown. Trim the excess material from the zip tie.

46) Reassemble the rear upholstery in the reverse order of removal:

Install the ten 14mm bolts that secure the hybrid battery cover in place.

Install the one 10mm bolt removed from the front right corner of the battery cover.

Clip the white battery vent tube retainer back into place

Install the two 10mm bolts on the top right of the hybrid battery cover (near the white clip).

Install the two 10mm bolts on the top left of the battery cover.

Reinstall the exhaust vent duct that runs from the battery to the battery fan and reinstall the six 10mm bolts.

Install the right side battery brace and secure the seven 12mm bolts.

Install the left side battery brace and secure the seven 12mm bolts. Make sure the HV cable retainer is in the proper orientation

Reinstall the HV battery cables using the special 10mm bolts previously removed. Do not over tighten these bolts, only torque to approx 10 in. lb.

Install the HV cable cover and secure the three 10mm bolts.

Install the HV battery cables access cover lock.

Reinstall the left and right side carpet trim pieces.

Install the battery cover carpet

Reconnect the 12V auxiliary battery ground cable to the battery.

Install the trunk carpet base sub-panel and trunk carpet.

Install the 12V accessory battery cover.

47) This is what the vehicle should look like at this point.

48) Continue the reassembly of the vehicle by performing the following:
Install the trunk trim panel and the five trunk trim panel clips

Install the seat back support bars with the four 10mm bolts.

Install the rear seat back by aligning it with the three upper alignment tabs and pressing firmly down.

Install the three 10mm bolts holding the rear seat back in place.

Install the rear seat headrests, if equipped.

Push the seat belt buckles through the seat bottom and install the seat bottom.

49) When not in use, the charger car harness can easily be stored inside the left side storage bin.

During use, the car harness can be routed as shown for easy viewing of charger status.

Click here for the Prolong Battery Charger User Guide.