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2003 – 2005 Civic Hybrid Plug-and-Play Car Harness Installation Instructions

Home / Honda / 2003 – 2005 Civic Hybrid Plug-and-Play Car Harness Installation Instructions

2003 – 2005 Civic Hybrid Plug-and-Play Car Harness Installation 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

Recommended: Volt meter, trim panel removal tool

1) Begin the installation by opening the hood.

2) Disconnect the 12V Aux battery.

3) You will need to remove the rear seat to access the IPU compartment.

4) Locate and remove the 10mm bolt at the center passenger’s left hip.

2004-2005 Civic’s have a second bolt at the right hip.

5) Pull up on the front edge of the lower cushion.

Remove the cushion from the car.

6) Remove the two bolts at the lower corners of the seat back.

7) Slide the seat back straight up to clear the top rear clips.

Remove it from the car.

8) Open the IMA disconnect cover and turn off the switch.

Reinstall the red safety guard.

9) Remove the IPU compartment cover Torx T-30 bolts.

10) Remove the little black interlock clip next to the switch.

11) Remove the IPU compartment cover.

12) Using a trim panel removal tool, remove the four trunk liner pieces in the order listed. There are five clips on the IPU cover trim (#2). The trunk latch cover (#3) is removed by pulling up and foreword (toward the front of the car). There are three clips on the IPU fan cover (#4), two of which are screw clips. Note how the IPU cover trim (#2) interlocks with the IPU fan cover (#4) and left trunk side trim (not removed) at the top corners so that it can be reinstalled properly.

13) Locate the IPU fan on the foreword right corner of the trunk. Unplug the factory IPU cooling fan sub-harness from the car harness at the small gray wire connector.

14) Install the Prolong plug-and-play car harness cooling fan wire assembly into the IPU fan wire harness. Secure the IPU fan controller to the trunk bulkhead using the supplied zip tie as shown. This does not need to be super tight, just enough to hold the IPU fan controller in place so it will not rattle. Trim the excess zip tie material and discard.

Note: Older non plug-and-play harness shown in image at left.

15) Route the charge wires (red & black) forward through the passenger side exterior of the IPU compartment and into the IPU compartment through the existing wire harness grommet as shown.

16) Test the voltage at the cables marked + and -. If you read more than 12V, put the cover back on and contact us.

After verifying low or no voltage is present, disconnect the + and – cables and these three connectors.

17) Unplug this cable and unclip it from the harness bracket

18) Remove the 10mm grounding bolt.

19) Remove the orange plug from the battery bracket. The orange plug cannot be opened until you release it from its’ clip.

Once it is off the metal clip, squeeze the button to release and separate as shown.

20) Remove the four 12mm IMA battery mount bolts.

21) Remove the 10mm IMA battery alignment bolt and clip.

22a) The IMA battery does not need to be fully removed from the IPU compartment in order to make the charge connections. If desired, the connections can be made with the battery partially removed, as shown.

22b) An alternate method to install the Car Harness is to remove the battery and position it on the rear seat sill as show in this photo. This allows for easier loosening and tightening of the small (fragile) screws that are used to attach the charge wires to the battery. We used this alternate method for the instructions to show both options.

23) This detail shows the connection points for the charge positive and charge negative wires. Do NOT route the red wire across the negative bus bar as shown in the next photo.

Be careful not to strip the small Phillips screws while loosening and tightening. Use firm downward pressure on the screws and turn carefully to loosen. Secure the wires to the IMA battery using the supplied zip tie as shown. It is normal for the red wire to have some black heat shrink tubing on the end as this is protecting the diode that protects the car harness in the event of an electrical short.

24) DO NOT route the charge positive wire across the negative bus bar as shown in this photo. This routing has a very high risk of short if something goes wrong. Don’t do it.

25) Route the charge wires as shown and secure using the final two supplied zip ties.

26) Reinstall the IMA battery in the reverse order of removal.

Reconnect all IMA battery wire connections.

Do not close the IPU compartment until after performing the initial function test as described below.

27) IMPORTANT – Test the charger before re-assembling the vehicle. Always connect the Charger to the car 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 IMA battery components. Plug the Charger into the car and turn the multi-meter on to the 200v DC setting. If your multi-meter has a power switch, turn it on. With the IMA battery circuit breaker still turned off, plug the Charger into the wall. After a few seconds, it should read approx 180 volts on the meter and both the charger and IPU fans should be running. Next, move the IMA battery circuit breaker to the on position. You should see the 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. Both fans should still be running. 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 wall, turn the IMA battery circuit breaker off, and disconnect the Charger from the car harness.

28) Cut a 2″ x 2″ ‘X’ shaped slot in the trunk liner and route the charger harness through the trunk panel as shown. Your trunk will not be fully reassembled as in the photo but that is OK as this will be covered in the next step.

29) Reassemble the trunk liners in the reverse order of removal and reinstall all trim fasteners.

Reinstall the rear seat in reverse order of removal. You are Done!

Click here for the Prolong Battery Charger User Guide.


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