anotherD3MISE

I have a 1995 honda civic. Automatic non v tec. About2 weeks ago i drove to a friends house then upon leaving discovered i had no fuel. The pump wasn't making its usual buzzing and the gas i had just put in did no good. I came back a few days later to tow it and it fired right upon. Parked it in front of my house on the way home and it would mot start again. The coil tests fine, there is no spark however. It wont prime with the key either.

The main relay has been switched and all fuses look good although i did not check the square box fuses under the hood up front just the traditional looking fuses.

The power coming from the main relay that goes though the yellow black wire or what i think is the feed wire gets 9.11 volts at alltimes. The ground wires on a23, a24 and a26 all check good.

Ive been told the green yellow wire from behind the computer feeds the coil but that wire is dead.

What needs to be checked to solve this?

ezone

That's a pretty busy area. A lot going on and all has to be right in order for it to all work correctly.

So...the main relay isn't switching power to it, or you've lost power to the hot side of that relay, or you picked the wrong wire (yel/blk instead of blk/yel)???



When the key is turned on, the main relay clicks on and connects fuse 31 (engine compartment box) to the yel/blk wire which supplies power to the ECM (A25, B1) all 4 injectors, IAC, purge, and O2 sensor.

As soon as the ECM powers up it's supposed to be able to ground the pump side of the main relay for the prime then wait for a starter cranking signal to turn the pump on again.
Check "good" how? Loaded circuit test will support how many amps on each ground?
Those all come from G101, so check the clump of ground wires on the thermostat housing (G101) for being clean and tight.



Which one? There's a nice green/yellow in the main relay that is used by the ECM to ground the pump side of the main relay (note: wire color is different in the integra diagram below)

There's also the same color wire for the radiator fan control and MAP REFV



FYI you REALLY have to pay attention to the main color on a wire vs tracer color, and get the order correct.
Yel/grn is very different fron grn/yel !!!

That said......There's a red/grn that turns into a yellow/green that operates the ICM which operates the coil, but if you have no pump prime with key on I seriously doubt chasing the ICM trigger is going to find the problem.


Got a good accurate wiring diagram of the PGMFI main relay and related ECM area?




Those suck, not clear if you blow it up...and not exactly the same as the FSM I checked.
Found a diagram for an Integra that is a lot more legible and it's ALMOST the same but not exactly, there are a few minor differences

anotherD3MISE

Those are the wires im working with and my ground test was with thosw three grounds i listed and the neg batt terminal.

Ill check to see if the main relay is getting signal then from there focus back on the computer after i learn what sensors are relevent for energizing the main relay

ezone

Study the wiring diagram to understand how that works.


The PGMFI main relay is two plain relays in a single box along with a couple diodes and resistors.

Simple "key on" energizes the part of the main relay on the left half of the diagram, this side powers up the ECM and several other items when its contacts close.

The relay in the right half of the diagram is only for the fuel pump and is controlled by a combination of the ECM, the first half of the main relay, and the cranking (starter solenoid power) signal.

ezone

You have bare wires in that bundle? Don't ever scrape insulation to test.

Backprobe to test instead.


Clip a paper clip or T pin into your tester leads alligator clip and insert the new long skinny probe into the connector shell to make contact with the back of the wire terminal.

http://www.enduringautomotive.com/ho...robe-a-sensor/

anotherD3MISE

I can jump the fuel pump on the relay connector between 7 and 8 i believe and turm the pump on. There is no continuity between terminal seven on the relay and the green yellow wire. Fuse 31 has power. Which wires coming from the computer besidea the one that turns into terminal seven do i need to check for continuity on key. On? The essentials and bare minimum wires that the computer uses to communicate with the sensors fuel and ignition systems.

ezone

I was gonna say that post didn't make one lick of sense then Ohhh I remembered...........

Terminal numbers stamped in the bottom of the main relay don't correspond to anything in the wiring diagrams. (and I can't see those numbers on your relay so I can't decipher the post at all)

The numbers in the diagrams refer to the wire harness connector numbering system, NOT the numbers on the relay.

I have to go by what's in the diagrams at all times (numbering and wire colors), never what's printed on the relays.

anotherD3MISE

I know wires and numbers change or dont always correspond so i always back up my observations by making sure the wire originates from the right position on the device or trace it all the way to the item it powers just to make sure.

Im getting the relay numbers from other posts on other threads anout no fuel. I used that to figure out if the fp was getting signal which it wasnt and like i said i have a continuity issue with seven on the relay which is the green yellow wire in my above picture.

I tried to pull codes but when i jumped the tester i got no response. The cel remains solid with key on and remains solid during tests for codes.

The sequence of events is really what i need to know once the key is turned to run so i can focus on each relevant wire.

anotherD3MISE

Im not getting signal from a21 on the ecm that feeds the yellow green wire at the dizzy its signal info.

ezone

Is that the same green yellow shown in the main relay diagrams as 'fuel pump control' from the ECM terminal A7, leading straight up to #1 on the main relay plug?
(remember, I can't see any numbers printed on your main relay)

If so, the ECM grounds that wire to turn on the fuel pump relay.


Coil trigger signal from ECM to ICM (igniter), after ECM makes timing corrections.....so ECM has to be turned on (powered up and grounded), it has to see all of the distributor inputs correctly (TDC/CKP/CYP) in order to generate a signal to be output to the ICM.

If the ECM is ok. See below.


Uh oh. No bueno.

Quick voltage check on the blue SCS plug,
black wire should be ground
and the brown wire should have some sort of voltage on it (probably 5v?)?
Yes?

Unplug ECM connector A: does the check engine light stay on? Or does it go out?

anotherD3MISE

Cel goes off with a terminals unplugged. The signal wire that turns into the green yelloe wire of the seven wires to the dizzy starts at a21 on computer. From there i believe it runs thru no 7 on relay but i have to find the exact place on the relay to confirm it. One does have continuity with the signal wire tho for sure.

The brown test wire had no voltage and idk what you refer to when you say scs blue wire

ezone

So the ECM is still controlling the warning light. Ok.

Your belief is incorrect here. You better study some correct wiring diagrams for your car.....That wire from ECM A21 doesn't go through the main relay at all.....and there is more than one of the same color wires at the ECM and they all do different things

You're only going to cause yourself unnecessary headaches and trouble if you can't obtain and follow correct wire diagrams for your particular car.




SCS is the 2 wire service check connector you jump to get flash codes out of the ECM.
You said you can't get your car to flash fault codes out so measuring on those two wires is a starting point to determine if they are actually connected to anything.
"zero volts" isn't the same as ground either. A wire not connected to anything would show zero volts too. Right?

anotherD3MISE

Thats my schematic and its correct.

anotherD3MISE

I need to know what activates a21 on the computer. Thats it. I dont need or want any information except what needs to be done by the computer and to the computer to energize that pulse wire.

I do not wamt a million answers to a million question i did not ask.

I followed the tutorial on
http://easyautodiagnostics.com/honda...system-tests-1
And from there the only failing test is the one having to do with computer signal to pulse..

ezone

Your diagram shows ECM A21 (white/yellow) goes to the starting/charging system.

Now you need the schematic of the starting/charging system to see where it ends.

anotherD3MISE

All this type of stuff we are talking about needs to be done on a computer and I'm using a dumb phone so i can barely see even magnified what the schematics see. Its a11 that has no signal going out. I have other pin outs that go a1 then a3, a5 etc etc then start on the second a row with the numbers skipped in the first row. So a2 then a4 etc etc on row two. But then all the colors in my autozone.com schematics from their chilton source matches what the wires would be color for color if row one had a a1 , a2, a3,and then a4 then etc etc. They all claim to ne the right wiring and pinout schematic.

The wires goin to the pick up get no juice at any point though.im goin to chase and investigate those wires until i find their origins then make an assessment of the ecu

ezone

To trigger the igniter (ECM to ICM), the ECM has to be powered up, the ECM has to receive the distributor signals (CKP, CYP, TDC).

I think if the system worked correctly and you aren't scared of getting lit up by 30,000 volts of spark, you could remove the distributor and hold it in your hand and spin the shaft and the ecm would try to send the signal to the igniter (ICM) to fire the coil. (distributor housing has to be grounded to the engine first!)

Got a buddy with a running identical car? Swap ECMs and see if yours will run and his doesn't.

anotherD3MISE

Im workin on the ecm swap but i cant find my buddy right now with her 94. I may buy an ecm and just bring it back since i can pull that depending on whos at my autozone. I wanna also try your igniter wire trick. Idc about the shock but i gotta figure out whicj wire does what on my igniter.

I also must add my igniter failed with flying colors on the tester and gave different but still bad results on other rounds with the testing tool including shocking the AutoZone worker smh. I think we got a bad icm bad pick up good coil and im not sure if that's interfering with the fp or if my computer isnt turning it on

ezone

Pump should prime during first key up--- without cranking nor any input from the distributor.



If the first half of the main relay supplies 12v to the ECM but the ECM can't activate the pump section of the main relay, the ECM is bad.

anotherD3MISE

So i should check the wirefor the ignition switch to see thats got power and the wire goin to the ecm from the relay and terminal 3 and 8 should have juice to allow the fp to activate is what i got from your comment.

ezone

I'd test this from the ECM.

I'd take the ECM out of its holder so I can reach all the wires while they are connected.
I'd use a voltmeter and backprobe ---you do know how to backprobe a connector for testing, yes?

http://www.enduringautomotive.com/ho...robe-a-sensor/





-------------------------
Following your posted ECM diagrams in post #13:

Connect your voltmeter black lead to the battery negative post

Use red lead to backprobe ECM terminal A13 or B1.
Turn key ON (do not start engine). Does voltmeter say 12v? (I assume it does)
------------------------
Key OFF.


Now Connect red voltmeter lead to battery positive post.
Use the black lead to backprobe ECM terminal A4 or A17 (whichever applies to your model).
Turn key ON (do not start engine).
Does voltmeter show 12v for about 2 seconds?

-----------------------

anotherD3MISE

I know how to backprobe. I should also note that a new distributer and a new main relay had no effect on the spark situation and there is still no signal going to the ecu from the pick up's two wires to pulse the ig coil or tell the ecu its time to send a pulse signal.

anotherD3MISE

It did start running again. My friend i had look at it claimed it was a fuse on the far right of the fuse box beneath the steering wheel. I dont know about all that but it has pretty much ran ever since except for a few non starts where upon finding spark the engine would crank over after the wire amd test plug grounded to the frame.