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-   -   Ecu ground? Main relay probs (https://www.hondaaccordforum.com/forum/general-tech-help-7/ecu-ground-main-relay-probs-60517/)

Dieskyver Dec 8, 2014 09:24 AM

Ecu ground? Main relay probs
 
Hello all. Bought my first honda bout 3 months ago(96 accord DX) with a bad auto trans with plans to swap to manual. I have the car back together now and have ignition problem(s). (No fire).
Currently I have no power to icm. I have key off power to main relay white/green wire and power to black/yellow ONLY when start/cranking. Not key ON/position II as most sources I read say it(b/y wire) should be. I soldered joints but still no dice. Fuel pump kicks on. No related cel just 21(vtec sol, donor car had vtec so what the hey)
I haven't jumped the relay because the instruction to do so rely on wire colors and I'm not confident mine are the same.
Driver side intake and valve cover ground feel/look solid. I plan on checking ecu ground by using MM to check V on battery ground to body ground.???
And check voltage at injectors. Don't know why just to know I guess. Should the blk/yel wire be constant battery voltage with ignition ON?
Im 3 weeks into trying to figure this out and a novice at circuitry so any insight would be appreciated.

TexasHonda Dec 8, 2014 12:16 PM

Blk/yel wire to distributor should always be hot when ignition switch is On. If not, ignition switch is likely fault. Check that fuses #15 & #18 of underhood fuse box are good.

good luck

Dieskyver Dec 8, 2014 05:02 PM

Thx for response. Apologies but I think
A) I've read my electrical diagram wrong. The dizzy blk/ylw isn't the same wire as the main relay blk/ylw is it? That was some of my confusion
B) the relay checks out. The harness on dizzy wasn't connected which means I'm back to my original no fire/icm problem.
I've replace the icm with a junkyard icm and got a single redish yellow spark then nothing. I tried grounding the blue wire to check for hi V coil spark and got nothing. I think I'm blowing icms. I've read about this in other posts.
When I connected my main harness to the POH ecm, I had to cut a sliver/leg of plastic off in order for the A connector to fit. Original ecm is POB and what was in when the 2nd icm "blew" . I guess now I should check continuity from blue wire to ecm to see if its shorting??? Ecm connector looks good. FYI, I've got a quality "Pull a Part" 15 min away but icm are few n far between.
Ps it's a2.2l Will update my profile now.

redbull-1 Dec 8, 2014 05:17 PM

The Blue wire from the distributor's ICM is the engine speed output (rpm) to the tach.

redbull-1 Dec 8, 2014 05:21 PM

The Yel/Grn wire to the distributor's ICM is the ignition input signal wire from the ECM/PCM.

Dieskyver Dec 8, 2014 05:35 PM

I thought it was but didnt know if the ecm used it as a signal. So it's the yello/green sending the signal. I just jumped it and got a spark out of coil.

This means
A) button/ cap are bad
And/or
B) tdc and crank pos sensors are suspect.
Am I missing anything?

Thanks for helping me keep my thoughts straight.

Sorry just read your ylw grn post I think I'm over thinking this.

Dieskyver Dec 8, 2014 06:30 PM

Could it still be a bad ecm ground?


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