tom_vickers

After having a hard time finding a cheap OEM radio to restore keyless entry for my 96-98 Civic, I decided to try wiring up the much more plentiful (in my junk yards at least) 99-00 keyless entry module. I searched and did not find this info already on the forums, so I decided to write up what I did. To complete this mod, you will need to a 99-00 Civic keyless entry module (in the driver's kick panel) with a stub of its connector harness. The module circuit card must be modified as shown below. Standard disclaimers apply: I am not responsible if you damage your car, etc, etc.

Modifying the 99-00 Keyless entry module
The keyless entry module from the 99-00 Civic is designed to be connected directly to the door lock solenoids (like the lock module mounted behind the driver’s door card on a 96-98). This change modifies the keyless entry module to function as a replacement for the 96-98 Civic keyless entry receiver inside the OEM radio. The change modifies the relays that typically drive the door lock solenoids with 12V & ground, to instead only drive a connection to ground when the door lock/unlock signal is received. When modified this way, the module outputs can be connected to the 96-98 Civic door lock controller through the stereo harness to lock/unlock the doors.

99-00 keyless entry module modification steps:

1. Remove the circuit card from the plastic housing.
2. Carefully unsolder the two relays labeled 1 and 2 in picture 1. If you are not familiar with unsoldering, you may want to get someone to help you with this step. You can damage the circuit card if you are not careful.
3. Modify relay 1 by bending the two pins furthest away from the module connector 90 degrees (bent pins can be seen on the right side of relay 1 in picture1.
4. Modify relay 2 by bending the two pins closest to the capacitor 90 degrees (so they will lay flat on top of the circuit board).
5. Solder a wire to the bent pin of relay 1 as shown in picture 1. The other bent pin will have no connection.
6. Solder a wire to the bent pin of relay 2 as shown in picture 2. The other bent pin will have no connection.
7. Place non-conductive (electrical or kapton) tape on the circuit card to prevent the bent pins from contacting traces on the top of the circuit card
8. Install the relays back into the circuit card, re-soldering the non-bent pins in the original holes.
9. Scrape some of the solder mask off a ground trace on the rear of the card and solder the other end of the wires as shown in picture 3. A ground trace runs along the back edge of the card under these relays.
10. Place the modified circuit card back into the plastic housing.

Pic 1 - Relay mods


Pic 2 - Relay mods


Pic 3 - Ground connection

Wiring the module into the 96-98 dash harness
It is a good idea to disconnect the negative battery cable while you are making these connections.

The modified 99-00 keyless entry module will be wired into the dash harness behind the car stereo location. With the stereo removed, pull the harness out the front of the dash to make the connections. Cut the indicated wires from the B harness (green connector) and solder/crimp them to the indicated wires on the 99-00 keyless entry module harness stub. The connections to the A harness (white radio connector) should be spliced to preserve the original connection to the A connector. For the door switch/dome light connection, join the two wires from the dash harness to the one wire from the 99-00 module. There will a number of connections on the 99-00 harness that are not used. I de-pinned these connections to minimize the number of unconnected wires. They may be added back if needed later.

NOTE: DO NOT USE AN UNMODIFIED 99-00 KEYLESS ENTRY MODULE! DOING SO WITH THIS WIRING WILL SHORT 12V TO GROUND AND BLOW FUSES AND/OR MELT WIRES!

Table of connections

The two connections highlighted in yellow should not be direct, they need an inline diode. These two circuits should be connected through a diode (IN4001 or similar). The stripe on the diode should be connected to the 99-00 keyless entry module, with the other side connected to the 96-98 dash harness. The diodes prevent a ground loop through relay 1 which will cause a problem with lock/unlock door switch on the driver’s door. See diode installation in picture 4.

Pic 4 - Inline diodes

When the wiring is complete, reconnect the battery. Program the remotes using the 99-00 programming procedure (look online, not provided here). The keyless entry system functions should work as expected:

• Single push unlocks driver’s door, two press to unlock all doors (see note)
• Single push of lock button locks doors, two pushes confirms with a horn beep
• Parking lights flash when locking

Note: The two-press unlock of all the doors is intermittent in my setup. Typically, the second press only unlocks the driver’s door. Occasionally it unlocks all the doors. After verifying that the relays work as I expected, I have a theory. The 99-00 module is designed to drive the door solenoids. The driver’s door lock is driven by one relay, while the other doors are driven by another. To unlock all the doors, it must activate both relays. My theory is that sending both the “unlock driver’s door” and “unlock all doors” signals to the lock controller is confusing it. I can probably fix this by adding another relay that prevents both signals from being sent out at the same time, but I am not going to add that to my setup right now.

After verifying everything works, the module may be tucked into the area behind the aftermarket radio. It may be possible to get other features working with additional wiring (alarm functions, dome light dim after door close). I have not yet explored those features. I hope this info helps if you want to try this mod.

Pic 5 - 96-98 Civic connectors

Pic 6 - 99-00 Civic connector

k.yepes

I found this thread searching for information on installing my remote start. My car is a 2000 Civic EX (USA edition). It already has power locks, and I want to connect the aftermarket remote start to use one keyfob to remote-start and operate the power locks.

I found this information on 12volt.com:

• Door Lock Green/White (-) Above Fuse Panel or Keyless Module or behind Radio Green Connector
• Door Unlock Green/Orange (-)
• Driver's Lock White/Red Driver's Kick Panel
• river's Unlock Blue/Red Driver's Kick Panel

I assume this is to the left of the drivers feet. Does anyone have a better explanation of the circuit? I assume that the module will provide the wires shown with a ground momentarily to make the doors lock or unlock.

k.yepes

I have completed my remote start install, and I can confirm my assumption was correct.