Touge Tuning

If i have an OBD2a ECU, and an OBD1 harness can i use these to make an OBD2a to OBD1 conversion harness? If so how exactly do u connect the wires from the OBD1 plugs to the obd2a terminals?

VTECVillain

You can make your own, but as cheap as they are nowadays you're better off buying one. If you wanted to make your own, you need to remove the OBD2 ECU connectors from the ECU board then solder the wire leads from the OBD1 ECU plugs to the proper locations.

Touge Tuning

well i need it ASAP and im located up in toronto so even sending a money order it would take too long. Plus since i have the 2 parts i need its basically free to make it.

NikoZai

What about the 3rd part?
THE KNOWLEDGE

LOL I guess you could make an adapter but you would need to masacre a OBD1 ECU to do it... ripping out the ECU side plugs to solder wire to the 2a plugs.. When you could sell the ECU for US$30 on ebay all day long, might even get US$100 for it.
How permanent do you think the swap is going to be? you could just cut and solder all the ECU wires to the new 2a plugs.

0mtber

iTrader: (2)

Go to http://boomslang.us

Touge Tuning

hmmm, never thought about hardwiring it. you think it would be a bad idea to hardwire the obd1 plugs to the OBD2a harness? I got a spare prelude obd1 harness and i dont mind cutting the obd2a harness plugs.

hondaZvic

its not that hard, i hardwired my 99ex to obd1. i have alot less wires jumbled up without that conversion harness. and the conversion harness i had gave me multiple problems with wires coming apart due to bad soldering.

since i made mine, i've had 0 problems

Touge Tuning

yeah i just started doing it and i think it will be much better hardwired. The conversion harnesses that ive seen werent perfect and the heat shrink would slide up or the pins move out.

Did you notice u had alot of left over wires on the obd1 plugs and the obd2a harness?

hondaZvic

what do u mean left over wires?

there are going to be extra wires on ur harness that will not be used in the obd1 plugs. all of the extra wires i had, i pulled them all out of my harness completely. my harness has no dead wires. only whats actually being used.

Touge Tuning

K so i need a little help here, i have a few empty wires on my OBD1 plugs and i have some spots on the OBD2a plugs where i think i should have wires but there arent any.

So here is what i need some help with

OBD2a harness
Plug "A"
-no #7 ESOL/E-EGR - EGR control solenoid valve
-IGP1 power ground (not sure which wire this connects to on the OBD1 plugs (#11)
-no #19 ALTC -alternator control"
-IGP2 power source (not sure same as above) (#24)
-no #25 VREF - Reference voltage
-no #27 FANC- radiator fan control
-#28 2WBS - EVAP bypass solenoid valve (not sure where this wire goes on the OBD1 plugs?)
-#29 VSV - EVAP control Canister vent shut valve (not sure where this wire goes on the OBD1 plugs?)
Plug "C"
-no #16 PSPSW - P/S power switch signal (car has power steering)
Plug "D"
-no#6 KS - knock sensor (shouldnt there be a wire for this?)
-no #9 EGRL - EGR valve lift sensor
-#15 PTAnk - fuel tank pressure sensor (where does this wire go?)
-no #16 EL (ELD) - electric load detector)

OBD1 plugs
Plug "A"
-A11 EGR control solenoid valve (have wire but nothing on the harness to connect it to?)
-A12 FANC engine coolant temp switch (have wire but nothing to connect to)
-A16 ALTC ( have wire)
-A17 IAB (GSR only?)
-A19 White Intake control solenoid (no idea?)

Plug "B"
-B8 PSPSW power steering switch (have wire)

Plug "D"
-D3 KS knock sensor (have wire)
-D10 ELD have wire
-D12 EGR valve lift sensor (have wire?)
-D19 & D20 reference voltage (no idea where these go)
-D21 and D22 sensor ground (no idea where these go)


Modified by scarlemthug at 10:28 AM 6/5/2005

Touge Tuning

like it seems like my car was missing wires but the car ran mint and it has PS, A/C and everything so im confused why im missing things related to this.

LMK if u can help me out man.

Touge Tuning

after checking everything carefully the only wires from the original OBD2a plugs left over are
A28, A29, D15 (this doesnt include the secondary O2 sensor wires and CKF wires)

Does this seem right or am i gonna need to run new wires for a few things?

Touge Tuning

need to figure this out ASAP

hondaZvic

from what u posted:
a28 & a29 are for EVAP.

what ecu are u gonna be using?

u dont need to wire in those EVAP stuff if emissions testing does not effect you.

on my harness i eliminated all the emissions and egr crap... (but then again, i dont have to worry about the testing either) so thats ur call.

heres a couple pix of how i did mine:

i started out with these:



and then it started to look like this before i got finished with it:


and then here is the finished product, sorry i didnt take a pic of the harness before i re-installed it...



as you can see in background of the second picture i made myself a diagram, with obd1 on the top half and obd2b on the bottm half, and on both i put where the wire was supposed to go with its corresponding wire. then i marked out spots that werent gonna be used and i marked where i had to run an extra wire or soo.. you should do the same. it helped so much.

Touge Tuning

im swapping an OBD2 B18b1 into my 98 dx (auto). I am gonna be using an OBD1 LS ecu. So Do I need to run extra wires and if so would there be a point if i dont have a connector to run them too?

I have like 4 pages of stuff printed out and I have a diagram that shows where stuff from the OBD1 plugs should go on the OBD2 harness. The problem is my EK harness doesnt seem to have all of the wires needed.


the ones that worry me are ALTC (A19), EGR (A7), FANC (A27), PSPSW (C16), KS knock (D6, EGRL (D9), PTANK (D15)

For the wires left over (A28, A29 and D15) where would i run the wires to on the OBD1 plugs?

hondaZvic

ok, i didnt think the integra ecu's had egr. if this is right, you can forget about the EGR stuff.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by scarlemthug &raquo;</TD></TR><TR><TD CLASS="quote">
I have like 4 pages of stuff printed out and I have a diagram that shows where stuff from the OBD1 plugs should go on the OBD2 harness. </TD></TR></TABLE>

compare them and you should be able to figure it out.

ALTC is labled the same on obd2 and 1
FANC is labled the same on obd2 and 1
PSPSW is labled the same on obd2 and 1
KS is the same
EGRL is anonther EGR component, you probally wont be using this one.
PTANK may be labled as FTANK


what diagrams did u print out? are they from the internet? if so send me the link so i can see what ur looking at.

Touge Tuning

ok so that would eliminate the EGR stuff on both sides because its an integra motor and ecu.

ALTC is labeled the same but there was no wire on the original OBD2a plug.
FANC is labeled the same but there was no wire on the original OBD2a plug.
PSPSW is labelled the same but there was no wire originally on the OBD2a plug.
Knock sensor is listed the same but there was no wire originally, i believe the knock is for vtec engines only?
EGRL eliminated
PTank is not listed on my OBD1 wiring schematic.

on the OBD1 schematic all i have left is A12 FANC, A16 ALT C, A19 Intake control solenoid???, B8 PSPSW, D3 knock (vtec only?), D10 ELD (no wire on the OBD2a side).

hondaZvic

so u need to know where those wires go on the obd1 clips?

Touge Tuning

nope, all those wires are present on the OBD1 plugs but they are not on the OBD2a harness at all.

The only one that im lacking from the OBD1 side is a place to wire the Ptank wire.

Also on the OBD1 connector there is to "reference voltage" wires, D19 and D20...any idea where these go?

hondaZvic

those referrence voltage wires are power wires. they have corresponding wires on both harnesses.
vcc1 = d19(obd1) --&gt; d4(obd2a)
vcc2 = d20(obd1) --&gt; d10(obd2a)

dunno if u need this or not...
http://tech2.hybridgarage.com/..._obd1

as for the missing wires on teh obd2a harness, they should be there, those wires are necessary for all harnesses. maybe the harness you got was incomplete.

Touge Tuning

woops, i did connect D19 and D20 just forgot to mark em off.

As for incomplete harness, thats impossible because the OBD2a harness is from my car which was running perfect 4 days ago with AC,PS and i passed emissions 2 months ago with flying colors.

hondaZvic

then if u know the harness is complete, than ur just not seeing it.

which helms manuals do u have?

Touge Tuning

yeah i know the harness is complete, i cant be missing anything because I am looking at the actual OBD2a plugs that i cut off the harness and theres nothing in the locations.

hondaZvic

okay,

compare ur ecu pinouts from ur 98 manual to this wiring diagram for obd1:
http://tech2.hybridgarage.com/..._obd1

make sure u have the right wires in these obd1 locations. if a wire is not there, find which one goes there and put it there. if there is a wire in a location that does not match the obd1 diagram, remove it.

as for ur ALTC, FANC etc... if u cant find the wire on the ecu clip, go to the sensor end, (where the clip plugs into ur fan or alternator and trace the wire all the way back and u will find it.)

also on my 99ex, my engine harness only had 2 clips, the 3rd one was inside the car. u didnt forget about ur 3rd clip did u?

Turbogixxer

Good job Zane