>>>>Building the Conversion Harnesses<<<<
It's possible to use an SAFC unit or an RPM switch to activate the VTEC. I chose not to do this, I wanted to install the entire thing like it was meant to be done, with factory connectors and run the motor on and OBD1 P28. I also tried to make everything easily removable, I plan on getting another CRX soon and I want to be able to put this one back to stock and swap my motor over to the new car. So before you even touch the car, get all the wiring ready, it will reduce downtime. All connections should be soldered, with heat shrink over the joints. When you are done and know everything works (ie running the car) then go ahead and tape it all to make it look pretty.
First off you want to make the dizzy conversion harness. Go to a junkyard and cut off the harness side plug for the dizzy you are using. In my case this was a D16Y7 dizzy from a 98 Civic CX. It would be ideal to cut the dizzy side plug from an OBD0 car, but I couldn't find one. I decided to solder into the main harness because I didn't have another choice, and it's only 9 wires so it's easy to return to stock. Basically you just need to match colours, here are OBD0, OBD1, and OBD2 dizzy wire colours and functions, these are all verified by me after hours of verifying and checking, don't trust every post you read on Honda Tech! This wiring kept me hung up for a week getting no fuel, but I got straightened out by Ryan (the Ry in Rywire).
OBD0 OBD1 OBD2 Function
Orange Orange Yellow CYP P
Small White White Black CYP M
Orange/Blue Orange/Blue Green TDC P
White/Blue White/Blue Red TDC M
Blue/Green Blue/Green Dark Blue CKP P
Blue/Yellow Blue/Yellow White CKP M
Large White Yellow/Green Yellow/Green ICM
Black/Yellow Black/Yellow Black/Yellow IGN
Blue Blue Light Blue RPM
For the ECU conversion (you don't need this if you are already OBD1, or aren't converting) you need to get the ECU and some length of harness to work with. I pulled a P28 from a 92 EX at the yard, and instead of unclipping the harness I just cut a good length of wires to go with it. I got a junk OBD0 ECU from a friend (these should be free, don't ever pay for a PM5!) and removed the plugs by pulling it apart and desoldering them from the board. Now all you need to do is connect the wires.
For OBD0, the big, 18 pin connector is A. The other two are sort of connected, the first 20-pin one is B and the last one, 16-Pin, is C. For OBD1, They read A B D, A is the largest, a 26-pin connector, B has 16 pins, and D has 22.
The numbers are read this way: Looking at the plug on the wire side, as if it were plugged in, the top left is 1, and below it is 2, next to it is 3. So, odd numbers run across the top and evens across the bottom. It gets a little tricky doing this since you are looking at different sides of the two types of plugs, so be very careful and work slowly. If you need to, put a little masking tape to mark the plug numbers.
Here is the conversion, I skipped unused plugs.
OBD0 Function OBD1 Function
A01 INJ1 A01 INJ1
A02 PG1 A23 PG1
A03 INJ2 A03 INJ2
A04 PG2 A24 PG2
A05 INJ3 A05 INJ3
A06 PCSol A20 PCSol
A07 INJ4 A02 INJ4
A11 EACV A09 IACV
A12 FLR1 A07 FLR1 (Main Relay)
A13 IGP1 A25 IGP1 (MR/resistor box)
A14 FLR2 A08 FLR2
A15 IGP2 B01 IGP2
A16 GND B02 LG2
A18 GND A26 LG1
B01 VBP/Hazard D01 VBU/Hazard
B03 ACC A15 AC Clutch
B04 FANC A12 FANC
B05 ALT A16 ALT
B06 MIL A13 MIL (CEL)
B08 ACS B05 AC Sw
B10 CYP P B11 CYP P
B12 CYP M B12 CYP M
B13 Fusebox B09 Starter
B14 ALT D09 ALT
B15 Ignition A21 ICM
B16 VSS B10 VSS
B17 Ignition A22 ICM
B19 ELD D10 ELD
B20 SCS D04 SCS
C01 CKP P B15 CKP P
C02 CKP M B16 CKP M
C03 TDC P B13 TDC P
C04 TDC M B14 TDC M
C05 IAT D15 IAT
C06 ECT D13 ECT
C07 TPS D11 TPS
C10 BKSW D02 (Brake Switch)
C11 Mil GND (MAP) D17 MAP
C12 SG2 D22 SG2
C13 VCC1 D19 VCC1
C14 SG1 D21 SG1
C15 VCC2 D20 VCC2
C16 O2Sensor D14 PHO2sensor
You will have a few wires left on the OBD1 plugs. You need to run 3 of these into the engine bay. I soldered them onto a plug close to the harness so I could pull the harness out of the car without a long wire running to the plugs.
A04 goes to the VTEC solenoid
A06 goes to the O2 sensor
D06 goes to the VTEC pressure switch
Everything else left on the harness is for things like Automatic transmission and EGR. If you got a harness from an EX manual (where the P28 came from) you should be all set here.
Now, you need to take a break and do something else. Before you put this thing in, you need to check it at least once for continuity. DO NOT just follow the wires, you need to make sure all the connections are good. Take a break in between checks, or have someone else do it, it's very easy to make mistakes. Don't tape it all up until you run the car with it!