Just finishing up my brother's B16A -> 1988 Civic DX swap. The horn works, the lights work, the brake lights work, but the ECU's not getting any power. We turn the key to the On position and there's no LED flash.

I've checked the leads and all the fuses in the car - they're all good - and I tested the main fuse block on the shock tower, and that all has power.

I'm not sure which plug - A, B or C - carries power to the ECU, so I haven't really tested B or C yet, but the A plug into the ECU has no power to any of the pins with the key in the 'on' position.

Any ideas? How can I troubleshoot this?

 

bump


[Modified by Mr. S, 6:21 PM 3/10/2003]

 

Ahh. I believe it's A plug. But will definitely check at my house since to verify for sure.

 

Thanks - let me know please

 

How are your grounds ? Alot of people forget to put the ground by the thermostat back on. Check that.

 

That one's on

 

are you getting any power to anything related to your ignition being on? such as your radio? Does your starter kick on if you try to start the car?

 

also check fuses, under hood fuses, underdash fuses and most importantly main relay

 

Yep, the starter turns the engine over, and we can turn the lights, blinkers, headlights, dash lights on, but we get no warning lights like oil pressure, seatbelt, check engine, etc.

We haven't done the main relay yet, we'll be pulling the dash tomorrow and for that we'll verify that all the connectors are plugged in. I have another main relay I can throw in and try, thanks for the suggestion sparkz

 

dude, i've got the same EXACT problem in my 89 dx with a b18a. all my grounds are good. i wired a switch to put power to my ecu and fuel pump, and now they turn on, but i just get a constant blink from my ecu and the car just backfires and sputters. good luck.

 

This sounds like a main relay to me (On driver's side of underdash, on outer panel.)

THe main relay throws a couple seconds of power to the fuel pump to rebuild the pressure and gives power to the ECU. If you can hear it, it gives off a quiet buzz for a second or two then clicks when you turn the key to acc. Take a screw driver and tap the relay with the handle after turning the key. THis might "unstick" it. Otherwise you might have to replace it - dealer part, around $ 65.

This failure is not uncommon.

 

Thanks for the replies, everyone; buzz kill

Oddly enough, I had no problems with it back when I bought the car in November. Do you think the main relay could just suddenly go kaput like that?

 

so what, that fixed the problem? i've tried 3 different main relays!!! could all 3 of them have been bad? wtf?

 

Did you check your 15amp fuse that is in your engine fuese panel that supplies 12v constant to the main relay and ECU? Its the second ATO type fuse up from the engine, above the three big main power wires that goes into your wiring harness.

Pull your A and B connectors from the ECU. A is the white one, B is the bigger black one.
B1 = 12V constant power, shoudl have ~12v all the time
A15 & A13 should be switch IGN1, should have ~12v when the ignition is switched on.

Check that out.

ALso can check the main relay pins make sure they are getting the right voltage. I don't remember the colors, etc. , but if the other stuff doesn't work, post again.

 

FYI: Usually the problem with the Main Relays is dry solder joints. Can usually fix it by taking it apart and resoldering all the joints.

 

Well, we did what you suggested rotten. Plugs A15, A13 have no power when the ignition is switched on Now what should we do?

EDIT: B1 has constant power.
Checked some of the continuity ones to ground (A2, A4, A16, A18 had continuity) they checked out.



[Modified by Mr. S, 5:04 PM 3/12/2003]

 

I used to be a volvo tech and the fuel pump relay would always need resoldering on the older cars. We just replaced em though...dealers, go figure

 

sounds like your northern hemispherical spatulaor duphalator modulator solenoid valve went bad...check that, there should be battery voltage going to it with ignition in the run position at 74 degrees ambient temperature. Hope that helped...later


[Modified by HonaTek1, 1:57 AM 3/13/2003]

 

Great thanks for the help.

 

Hrm... I would make sure that the main relay is getting power.

Does it click when you turn on the ignition?

I don't have the diagram in front of me but make sure that the main relay is getting the ~12v always where it is supposed to, and make sure when you switch the ignition that it is also getting that signal.

-k

 

rotten

I checked the main relay power today, and one of the connectors is getting a constant 11.6 volts (low battery), but the other ones have no switched power!

 

bump... anyone know what to check for here?

 

(Basso profundo voice) "Nobody knows... the trouble I've seen"

Seriously though... aaaaanybody know which wires provide power to the main relay or ECU on an ED/EF Civic DX? How can I check these wires?

 

just for you check out the diagram:

http://www.we-todd-did-racing.com/we...MxeTU0MQ%3D%3D

http://www.we-todd-did-racing.com/we...MxeTU0MQ%3D%3D

 

Thank you for the diagrams

But I don't know what kind of DX that 2nd diagram with the troubleshooting flowchart is for... I've never seen or heard of an inertia switch in my life and there's no matching wires on the harness right now either (there's no battery voltage to the main relay when ignition is turned on so that's where the flowchart leads) Stuck again.. d'oh... gotta keep looking I guess


[Modified by raene, 8:16 PM 3/15/2003]