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2004 - 2009 Toyota Prius Plug-and-Play Car Harness Installation Instructions

Note: These instructions are for the new plug-and-play Prolong™ Car Harness.  If you have the older non plug-and-play version, click here for instructions.

(Click on below image
for larger photo)

Time Required: Approx 1-1.5 hours

Tools Required:
8mm, 10mm, 12mm, 14mm sockets
#2 phillips screwdriver, #0 phillips screwdriver
(Recommended:) Volt meter, trim panel removal tool

1) Open the rear cargo area lift gate and remove the cargo cover and trunk mat (if equipped).

Fold rear seats down.

2) Remove the left side storage bin cover and cargo area floor panel

Remove main storage compartment.

Remove left side storage bin 10mm locknut, and remove left side storage bin.

3) Remove the rear cargo area trim by firmly pulling straight up on each end and working toward center

Remove the tail light access covers (not shown).

4) Remove the battery carpet cover. This is held down by two 10mm bolts (circled), three spring clips on top (lettered), two clips on the font corners (square), and some velcro.
5) Remove right side trim that covers 12v accessory battery.
DO NOT SKIP THIS STEP!

6) Disconnect the 12V auxiliary battery by removing the ground cable from the vehicle body. Wrap this in a plastic bag and tuck out of the way such that it cannot accidentally connect with body ground.

7) Remove the 10mm side panel trim bolt as shown.

Remove rear lower cargo tie-down (not shown)

Carefully pry at rear of cargo area light to remove it from left side panel.

Unplug light and set aside.

8) Lift up and forward on the rear door trim pieces.

Remove the 10mm bolt and trim clip as shown.

Remove the cargo area side panel by starting at the rear top and prying inward.

Repeat process to remove right cargo side panel.

9) Remove the two 14mm bolts holding the left side rear seat top.
10) Slide the left side rear seat top forward and store.
11) Remove the five 12mm bolts from the left side battery brace as shown.

12) Remove the two remaining 12mm bolts from the left side battery brace as shown.

Remove the left side battery brace.

DO NOT SKIP THIS STEP!

13) Remove the hybrid traction battery main disconnect by pulling up on the large orange disconnect lock ring, rotating it outward and down 90 degrees, and removing the disconnect.

14) Remove the hybrid battery junction cover by removing the three 10mm bolts and two 10mm nuts shown.
SKS Equipped Cars:

15a) If your Prius is equipped with the Smart Key System (SKS), begin the installation of the car harness by removing the OEM 10mm nut and installing the first anti-tension wire stay on the SKS receiver anchor bolt as shown.

Reinstall the 10mm nut and tighten.

Non-SKS Equipped Cars:

15b) If your Prius is not equipped with the Smart Key System (SKS), the white receiver unit shown in the photo may not be present. Instead, use one of the large zip ties provided and attach the car harness to the factory harness at the location shown in the white shadow box.

Better image coming soon

16) Lay out the car harness as shown.

 Note: The car harness in the photo is a 'Discharge Ready' car harness. If you have a 'Standard" harness it will vary slightly.

17) Route the car harness high voltage charge wires as shown and secure using two of the small zip ties provided as shown in the red circles.

 Note the routing of the harness behind the OEM wires as shown in the red square.

NOTE: Do not connect the car harness wires to the motor side of the battery disconnect relay.

Remove the while plastic covers to access the battery side of the battery disconnect relay.

18) 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. .

Reinstall the white plastic terminal covers (not shown).

19) Reinstall the hybrid battery junction cover by installing the two 10mm nuts and three 10mm bolts and tighten.

 When installing the rear lower 10mm bolt, attach the second anti-tension wire stay as shown.

20) Attach the third and fourth anti-tension wire stay as shown.

(Non plug-and-play harness shown.  Plug-and-play harness will have wire pigtails and fan control cover pre-installed)

21) Begin the installation of the hybrid battery cooling fan control sub-assembly by locating the fan power wire as shown.  Unplug the fan wire harness from the fan by reaching behind the fan and disconnecting.

NOTE: If you are having trouble removing the plug, you can remove the fan intake duct and fan.  See step 23 for how to remove the intake duct.  Remove the three 10mm nuts holding fan assembly in place and rotate fan to gain easy access to the wire plug. 

OPTIONAL BUT RECOMMENDED:

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

Remove the hybrid battery cooling fan intake duct by removing the three retaining clips (one of three shown). Push the center of the clip down to free it, then remove the clip.  Remove the duct from the battery fan inlet.

OPTIONAL BUT RECOMMENDED:

23) 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.

It might be easier to remove the fan completely to facilitate the cleaning process.

Reinstall the fan and/or duct when complete.

24) Install the hybrid battery cooling fan control sub-assembly by locating and connecting to the existing wire harness as shown.

Secure the hybrid battery cooling fan control sub-assembly in place with three of the provided small zip ties.

The hybrid battery cooling fan control sub-assembly should be firmly in place and not move freely.

35) 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 250 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 sub-assembly 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 and no amperage.

36) Next, carefully connect hybrid battery main disconnect.

Once the disconnect is reinstalled, be sure to PUSH THE LARGE ORANGE DISCONNECT RING DOWN TO LOCK IT INTO PLACE!! IT WILL NOT WORK UNLESS LOCKED DOWN. YOU HAVE TO PUSH IT DOWN TO LOCK IT IN PLACE.

37) 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 and amperage.

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.

38) Before reinstalling the rear cargo area upholstery, remove the displayed foam block from the right cargo side panel.

 This allows better airflow and cooling of the hybrid battery cooling fan control sub-assembly.

(Refer to disassembly
sequence for
respective image)
39) Reassemble the rear cargo area upholstery in the reverse order of removal:

Install the left side battery brace.

Install the left rear seat top.

Install the left and right cargo area side panels.

Reposition the rear door trim pieces.

Install the cargo area light.

Reconnect the 12V aux battery ground.

Install the right side trim that covers 12V accessory battery.

Install the battery carpet cover.

Install the tail light access covers.

Install the rear cargo area trim (lift gate latch trim).

40) Install the left side storage bin and route the wire harness as shown. Secure the left side storage bin with the OEM 10mm plastic locknut.

 Install main storage compartment.

Install left side storage bin cover.

Install cargo area floor panel.

41) 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.

(No image)

Click here for the Prolong Battery Charger User Guide.


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