Hello, I was wondering if anyone had a schematic for the injector wiring on a 91 Civic Si. One of my wires is shorting, or grounding somewhere and with out a schematic it's proving to be nearly impossible to find. The problem wire is the brown wire (ground wire) on my No.1 injector. I'm getting 12v from the red/black wire, but the ground wire is dead. I was wondering if there was a relay, resistor box, or something in between the injector and the ECM. I need somewhere to start to find the problem with this wire

I want to say thank you ahead of the time, also. I've asked many questions on here and a few people have responded consistently and I appreciate all your help here at Honda-Tech, you're all awesome.

 

there you go


the brown wire for your number 1 injector
goes to A1 on your ecu wiring


and now some info you need to know the red and black wire on that injector plug is supposed to have the volts
but the brown wire is the ground wire
but... it pulses when the engine is running
and primes when you first turn the key
it isnt always grounded

if your not getting your ground with this brown wire
id try testing to see if the wire is just broken somewhere
and if it is then id just run a new wire and call it fixed

let me know how your testing goes
and goodluck

 

I de-pinned the brown wire in A1. Then I re-pinned a new wire into A1, and ran that wire straight to the injector plug on the No. 1 cylinder and still got nothing. All other injectors are reading 12v+ but no matter what I do I cannot get the brown (ground wire) on the No. 1 cylinder to give anything. I even went so far as to changing ECUs to see if that was the problem. I am at a complete loss, and about to lose my mind, because I need this car running!

EDIT: I also checked the plugs, and the wire that I used to manually run from the ECU to the injector. All show good continuity.

 

Could this somehow be a problem with the main relay? I am thinking it might be an ECU grounding issue. I've been scouring over schematics for hours trying to solve this problem, and am not getting anywhere fast. I am wondering if this is a physical ground that could have came lose that is causing this problem.

 

Does anyone have any idea which of these wires (A12, 14, 13, or 15) controls the A1 ground wire for injector No. 1?

 

It's not a problem with the relay, I bought a new one and changed it out, and that didn't fix it.

 

Anyone have any idea of a work around, or a fix?

 

yea try switch the injectors around
so switch out the #1 injector with the #2 and then put everything back together and see if its just the injector thats not firing
that might be whats going on here

you never know

also if your really at the point where to want to cheat to get the car fixed
injector #3 fires at the same time as #1

 

I am pretty close to being at the point to cheat, I don't really want to, but I am close. My cousin figured that out the other day, that #1 and #3 fire at the same time. So if all else fails, I guess I will splice off of the #3 ground.
With that said, right now I am trying to find a diagram of all the ground wires in my car. I suspect one of them might be loose, or disconnected and causing the problem. A while back I removed my dash to replace my brake booster, and I am thinking I might have disconnected a ground somewhere.
What i've been trying to figure out is, if each injector is grounded independently from the ECU. I just can't understand why only one of my injector ground wires fails to work if that isn't the case, especially since I ran a wire straight from the ECU to the injector, and still got nothing.

Thank you for your replys Marcos, always a great help. I appreciate the confirmation on the #3 and #1 injectors a lot. My cousin suspected that was how it worked, but I wasn't entirely sure.