After reading all the posts about VTEC engagement and everybody comparing when and how it activates, I got curious.  So I read my manual and decided to do this mod so I would know exactly when and under what conditions VTEC is activated.  You may be surprised, it doesn't always come on at the same rpm.

What Mod 1 does:

This mod causes the right turn signal indicator to illuminate when VTEC is active.  It does not interfere with the turn signals or hazard lights, but it does have priority over the turn signal indicator ( the right turn signal indicator will be lit steadily when VTEC is engaged, even if the turn signals themselves are blinking).

What Mod 2 does:

Mod 2 adds a VTEC counter to count the number of times VTEC is activated.
See here for details.

Skills and tools required to install:

bulletRemove interior trim panels (driver's side foot well)
bulletSplice wires using crimp connectors (2 wires under the dash)
bulletSoldering Iron. It's easier to solder the diodes together, but you could do it with crimp connectors.

Parts required:

bullet2 general purpose diodes rated 50 volts 1 amp (1N4001 or similar)
bullet18" of 18 to 22 gauge wire
bulletcrimp splice connectors or solder (your preference)
bulletHeat-shrink tubing or electrical tape

If you bought the above stuff from Radio Shack it would maybe cost you $5.

Optional installation:

You only need the diodes if, like me, you use the turn signal indicator to show VTEC activation.  I used it so I wouldn't have to find a place to mount a separate indicator, plus it is right next to the tach and is easy to see.  If you decide to use a separate indicator lamp or LED, you don't need the diodes and installation is even easier.  See Optional Installation Procedure at the bottom of this page.

Installation Procedure:

  1. Connect the diodes together per the photos, and attach wires. Photo A
  2. Insulate with electrical tape or heat-shrink tubing.  Photo B & C
  3. Remove the driver's side door sill trim - 3 clips in the middle, 1 locking tab at each end
  4. Remove the driver's side kick panel - 1 screw, 2 clips.
  5. Locate connector 404 under the driver's dash, and look for the green wire with a yellow stripe.  Be careful, there are two green/yellow wires in this connector.  The one you want is between a red/blue and a green/red wire.  The one you don't want is between a red/blue and an empty wire socket (unless you're in Canada, in which case the empty socket has a blue/white wire in it.  See photos D & E
  6. You will need to cut this green/yellow wire, and splice the diode assembly between the cut ends.  Make sure the wire from the gauges connects to the diode joint (red wire in photo ), and the wire from connector 404 goes to one of the single diode wires (white wire in my photo).
  7. Run the remaining wire (green in my photo) down to the ECU.
  8. Locate the green/yellow wire on the ECU (it's the only one on this connector).  See photos F & G.
  9. Using a wire-tapping connector, splice the wire from the diode assembly into the green/yellow ECU wire.  Do not cut the ECU wire, you just 'tap' into it.
  10. Put everything back together.
(A)  Solder diodes together & connect wires (B)  Add heat-shrink over solder joints
p7.jpg (15072 bytes) p8.jpg (19548 bytes)
 

 

(C)  Add heat-shrink over diodes (D)  Picture of connector 404
p9.jpg (17402 bytes) p2.jpg (49407 bytes)
 

 

(E)  Close-up of the green/yellow wire
p3.jpg (47072 bytes)

The yellow arrow points to the green/yellow wire as it enters my heat-shrink splice.  I decide to solder all the connections, and managed to hide the diodes inside the black wire loom cover.  The wire bundle on the left side of the photo goes to the gauge assembly.  

 

 

(F)  Picture of ECU connection (G)  Close-up of ECU connector
p1.jpg (56054 bytes) p4.jpg (56668 bytes)

Optional Installation Procedure:

  1. Purchase a suitable indicator, such as an LED indicator designed for 12 volts or a low current beeper.  Make sure it is rated for 12 volts DC and a current consumption of less than 0.1 amps (100 milliamps).  The indicator will be powered directly from the ECU, and currents higher than this may damage the ECU.
  2. Mount your indicator in a place you choose, and connect the negative side to ground.
  3. Remove the driver's side door sill trim - 3 clips in the middle, 1 locking tab at each end
  4. Remove the driver's side kick panel - 1 screw, 2 clips.
  5. Run the positive wire from your indicator to the ECU.
  6. Locate the green/yellow wire on the ECU (it's the only one on this connector).  See photos F & G.
  7. Using a 'tap-in' connector, splice the wire from your indicator into the green/yellow ECU wire.  Do not cut the ECU wire, you just 'tap' into it.
  8. Put everything back together.
  9. Test (more VTEC time).

 

Diagram for using a transistor to drive the factory security LED as a VTEC indicator