How to Modify 00+ P11/B15's to Work With Older ECU's
Getting an older ECU, OBD2 16 bit or OBD1, into 2000+ B15/P11's is not a walk in the park but it's not impossible. There is quite a bit of wiring involved, but as long as you don't go crazy reading the FSM you should be fine.
OBD1 to OBD2 to OBD2 32bit ECU Pinouts
There are two ways to go about it, repining and step down. If your on a B15 Repining is a must because there is no room in the ECU box for a step down harness.
Repining the Harness
About half of the pins should just transfer over to the OBD1 plug, the other half will need to be cut and reattached with a different ECU plug in (there are two types of plugs in the harness).
Once it's done it will look a lot better then a step down.
Step Down Harness
I cut the plug of the ECU, then started soldering onto it.
Took a bit of matching and stretching and shortening of some wires.
Finally filled it with epoxy so that it wouldn't rattle out and come loose. I had much less epoxy before, but the RPM wire came loose. Mainly because the epoxy stuck to the heat shrink tubing not to the wire, thus the wire was still free to move. With the Epoxy being glued to the wires, it wont move at all.
IACV-AAC Valve - Brown VE Plug
This is the main idle control valve, you only need to take two wires out of the RR IACV. The Green/White and Brown, everything else needs to be shielded off.
VE Plug : RR Plug
Brown/Yellow (BR/Y) : Green/White (G/W)
Light Blue (SB) : Brown (BR)
You will need to extend it to reach to the VE IACV
IACV-FICD Valve - Purple VE Plug
This valve is used to give additional air to raise the idle while your AC is on.
VE Plug : RR Plug
Blue/Red (B/R) : Blue/Red (B/R) (Post Relay, run a wire from AC compressor to FICD plug)
Yellow (Y): Ground to intake manifold (ECU ground)
Splice the Yellow wire to the ECU Ground
The Blue/Red wire runs from the AC compressor to the relay.
Splice a new wire into the Blue/Red wire post relay before the compressor. This wire will need to be stretched to the purple VE plug.
MAF Plug
5 Volt Read - Blue
Positive - White
Ground - Green
Red - Isolate and shield off.
TPS Sensor Power - Low Voltage
On P11/B15's the TPS Power wire is used for multiple sensors, while folder older had a pretty much dedicated power source for the TPS (99 Sentra's and 99 G20's share the TPS power with other sensors too). The wire color is P/L, or in English, Pink with Blue stripe.
I kept on having issues with my TPS voltage being too low. After much research I finally was able to pint out the extra sensors that where using up the power. Basically older ecu's are not designed to provide the extra power that newer cars require.
P11/B15 Sensors
Coolant Sensor
I was able to successfully use OBD2 coolant sensor with OBD1 ECU, no change needed here!
OBD1 to OBD2 to OBD2 32bit ECU Pinouts
There are two ways to go about it, repining and step down. If your on a B15 Repining is a must because there is no room in the ECU box for a step down harness.
Repining the Harness
About half of the pins should just transfer over to the OBD1 plug, the other half will need to be cut and reattached with a different ECU plug in (there are two types of plugs in the harness).
Once it's done it will look a lot better then a step down.
Step Down Harness
I cut the plug of the ECU, then started soldering onto it.
Took a bit of matching and stretching and shortening of some wires.
Finally filled it with epoxy so that it wouldn't rattle out and come loose. I had much less epoxy before, but the RPM wire came loose. Mainly because the epoxy stuck to the heat shrink tubing not to the wire, thus the wire was still free to move. With the Epoxy being glued to the wires, it wont move at all.
IACV-AAC Valve - Brown VE Plug
This is the main idle control valve, you only need to take two wires out of the RR IACV. The Green/White and Brown, everything else needs to be shielded off.
VE Plug : RR Plug
Brown/Yellow (BR/Y) : Green/White (G/W)
Light Blue (SB) : Brown (BR)
You will need to extend it to reach to the VE IACV
IACV-FICD Valve - Purple VE Plug
This valve is used to give additional air to raise the idle while your AC is on.
VE Plug : RR Plug
Blue/Red (B/R) : Blue/Red (B/R) (Post Relay, run a wire from AC compressor to FICD plug)
Yellow (Y): Ground to intake manifold (ECU ground)
Splice the Yellow wire to the ECU Ground
The Blue/Red wire runs from the AC compressor to the relay.
Splice a new wire into the Blue/Red wire post relay before the compressor. This wire will need to be stretched to the purple VE plug.
MAF Plug
5 Volt Read - Blue
Positive - White
Ground - Green
Red - Isolate and shield off.
TPS Sensor Power - Low Voltage
On P11/B15's the TPS Power wire is used for multiple sensors, while folder older had a pretty much dedicated power source for the TPS (99 Sentra's and 99 G20's share the TPS power with other sensors too). The wire color is P/L, or in English, Pink with Blue stripe.
I kept on having issues with my TPS voltage being too low. After much research I finally was able to pint out the extra sensors that where using up the power. Basically older ecu's are not designed to provide the extra power that newer cars require.
P11/B15 Sensors
- Refrigerant Pressure Sensor - Keep this one, needed for AC usage
- Absolute Pressure Sensor - Disconnect, located next to the MAF
- Evap Control System Sensor - Disconnect, located in the rear of the car near the vapor canister
- MAF - This is the red wire that you should have shielded earlier
Coolant Sensor
I was able to successfully use OBD2 coolant sensor with OBD1 ECU, no change needed here!
Last edited by Vadim
on 2014-12-10
at 02-52-01.
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Originally Posted by Dema 
No mod's to Harness No intake manifold swapping !!! I just wanted to thank you for posting the wire colors and pin out for the 32bit ECU
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