Sparksman

Hello everyone! Its been awhile since I've been on, The lude has slowly been coming along. All thats left are vac lines and wiring. I deleted all my emissions related things. Now I have extra male plugs and Im not sure if I forgot where they go, or if just not needed.

Ive tried looking for and could not find a H series harness diagram of what each plug goes to. Theres 9 Mystery plugs

#1-This plug is right below the fuse box


#2-I believe this one was for my EGR, correct?


#3 This one is right next to my MAP sensor


#4 I believe this one behind the driver headlight is meant to go the the on pump CPS that i dont have.


#'s 5 & 6 These two are between engine and firewall


#7 This one is between engine and firewall but lower down near knock sensor and fan switch sensor area.


#8 This ones obviously down by axel


#9 This one is by the power steering pump tank




Anyhow thanks for any and all help in advance!

v4lu3s

the one by the driveshaft is your o2 sensor.
I know it doesnt help you now, but i always put tape flags with writing on each plug to tell me what it was plugged into so when it goes back in i am not confused ever.

Sparksman

I thought I plugged the O2 in already...lol. Thats why I asked, not sure if im overlooking or dont need. Thanks!

Also my old harness was in real bad shape so I sold it and bought a new one. Then I did write on masking tape for the engine bay plugs, but the sharpie faded over time and was useless... This is a 3 year on going project, it wasnt yesterday I took this apart either lol.

v4lu3s

what year is the car?

spray004

Hard to give answers without wire colors to each plug.
Download the service manual. Look in the Fuel & Emission section. They have all of the wiring diagrams for the fuel & emission sensors. It'll show the shape of the connector and the wire colors.

http://hondatech.info/downloads/Auto...e/Prelude%204/

yohan

My question on this, which I'm sure you already have done - any CEL codes?

I know waaay back when I swap my H23 to H22 I had an extra plug that went by the thermostat housing that controller the pass. side rad fan. That might be one of them below the dizzy.

v4lu3s

i think that plug by the power steering reservoir is likely egr/evap emissions control stuff, if i recall correctly there are two devices that used to mount there that had a plug in them.

Sparksman

Hey thanks for the replies man, Ive just been busy the last few days... Ya true the gas evap was back behind the TB. Now that I think about it I should have one for a AIBs and a resistor box right? Its been so long I forgot half the crap it came with lol.

Its a 94' Vtec model, Here is a link to my build thread---

https://honda-tech.com/honda-prelude...dates-3201446/

Im running a Neptune RTP w/datalogger, I was hoping once I started it I would know. But I need to buy hoses for custom vac and coolant lines before I try to turn her over.

The fan switch on the water-neck off the head is already plugged in.

v4lu3s

then i think the 2 wire by the reservoir is the egr solenoid connector. there used to be a bracket with the solenoid and control valve sitting there is i recall correctly.
the IAB plug will be on the harness under the manifold right near the IAT plug.
the resistor box plug will be right at the driver side end of the engine harness right by the bottom of the windshield..

anyway here goes

#1 is the control solenoid for the air cleaner where the prelude has that secondary flap that opens and closes.

#2 appears to be egr valve

#3 evap purge control solenoid

#4 Your guess is BETTER than mine, im clueless there.

#5 #6 I would guess IAT (double check wire colors) and the other one could be the one that plugs into the high pressure power steering hose.

#7 IAB (check wire colors)

#8 still looks like o2 sensor to me, i do not know of any other 4 wire plug in that area, i would double check the wire colors...

#9 is the egr frequency solenoid

Sparksman

My mani temp is plugged in, as well as the power steering. I feel only 1 of the two in #'s 5 & 6 "bottom one" is unaccounted for. I do believe I have all my important ones, and what ever it is Il find out when I start it. Or its just another emissions thing i deleted and dont have to worry about it.

Thanks again V4lu3s, been a huge help!

v4lu3s

the injector resistor plug i believe has 5 wires going into it, and is square and gray. possibly has spots for 6 wires with one blocked with a rubber plug. none of the plugs appear to have that many wires to me...

Sparksman

Hmm... Well all my important things are plugged in, so Im just goign to see what happens. Im running saturated k series RDX injectors anyhow, on Neptune RTP. Dont need or have a resistor box.

v4lu3s

when I eliminate a resistor box I either clip that plug and solder the 5 wires together, or I cut the plug off the resistor and solder those wires together. I prefer the second way since that means I can go back to stock easier if I need to.

Sparksman

Il be over to see the car on tuesday, il check it out and see what's going on. It sucks trying to figure it out and not having the car in front of me...

Sparksman

lmao... SO looking at my pic I see the resistor box.... I had some saturated A4 injectors in it last, so it was never plugged in. I seen that little silver box in my pic and was like wtf is that lol... I thought I took that off a long time ago. I just plugged it in is all, I was in work mode . Thats why I didnt see it unplugged.

So do I need to solder all 5 wires together? My last harness must have had that done already, those were the injectors it was running on a chipped Po6 when I bought it.

v4lu3s

yes, the power input wire goes into the resistor pack which splits it out to each injector. With my current crx i cut a plug off at the junkyard and soldered those wires together (in case i go back to stock and sell the car), while prior cars that i had no intention of going back to stock i just cut the plug, soldered, heatshrinked, taped and wrapped back into the harness under the accordion tubing.