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Default 98 si b18c1 swap blowing fuse 31
Here is my situation, I have searched, read and tried to apply fixes in all the articles pertaining to this situation that I can find. I am hoping someone can help me with this!
I have a 98 civic si (Canada) but was made late in the year so it's actually a 99 harness and obd2b. I have swapped in a b18c1 from a 2000 gsr, also obd2b. Now every time I crank the motor fuse 31 on the panel under the driver side cabin panel blows. From reading I understand this fuse powers ECU ICU and main relay. I think I have it narrowed down to ECU ( possible short on the blue/white wire powering or possibly a short down stream from ECU?) the reason I think that I has to do with ECU is fuse 31 does not blow when main relay and ICU are plugged in, only when I plug ECU and turn over does the fuse blow.
I don't think the short is in the ECU (integra) because I also plugged in the original ECU (civic) and both blow fuse 31.
The car ran with the d series motor but will not run since I swapped. There is fuel getting to the rail but no spark. Hope I have given enough info.

 
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Too many variations, too many choices in diagrams.

Fuse 31 feeds the PGMFI main relay, and the ECM. 2 different circuits from the same fuse.

You disconnected the main relay and the fuse did not blow, right?

I'd say to do continuity checks on the wiring from fuse 31 to the ECM terminals, make sure it actually goes where it is supposed to go with no short to ground along the way, according to whatever diagrams are right for your setup.

Different ECMs use don't all use the same terminals for the starter signal input.
A quick browse of 98 year diagrams found at least 2 very different terminals in the ECM for that. Make sure of which terminal your particular ECM needs that input on.

 
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I will look into that further today. I have performed continuity tests and am getting an ohm reading on the blue/white power fed from 31 at the main relay and the ICU but cannot get a reading on the blue/white wire that goes into C clip into the ECU. And yes the fuse only blows when ECU is plugged in. Main relay and ICU do not blow the fuse if they are plugged in or not plugged in, makes no difference. Thanks for the reply!

 
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Does your ECM need that wire moved to the A connector instead of C?

 
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To be honest the more I look at this the more I'm getting confused. I only have a b & c plug. I know that the obd2b has the A plug as part of the cabin harness
https://www.google.ca/search?q=a+con...60pPdCuoFoM%3A
But I cannot find a plug that matches this pin out diagram
https://www.google.ca/search?q=2000+...3_kkb_vI3MM%3A
Every pic I have seen has 3 plugs plugged into the obd2b harness. Also when I got my motor tranny and ECU (all from the same 2000 gsr) there were 3 plugs plugged into the teg ECU

 
Rep Power: 518

You may need a wiring diagram for that exact car, to see which connector and terminal this 'starter signal' wire is supposed to be in.
Or find it in the harness that was in that car if you have it?

One of your links says Connector A24 = STS....STart Signal?

I'm not sure that there is anything on the 'output side' of the ECM from that input, I was under the impression that it is just used for fuel enrichment as part of starting strategy. I could be wrong on that, I've been wrong before.

Did you get a wire pinched during the install?

 
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So I figured out what my issue was. This car is new to me and I was not aware of its history. I checked the vin on the D16Y8 that I removed for the B18 swap against the vin on the car, Sure enough it was not the original motor but was out of a 99 (obd2b) and had the 2b engine harness and ecu. The car & cabin harness being a 98 is obd2a. So previous owner swapped the motor and mated the 2 harnesses. Thia allowed the car to run but certin things (speedo,tach,rad fan,reverse lights etc) would not work. I got an engine harness out of a 98 civic and ecu out of a 98 gsr and now she is purring away. Thanks to ezone for the help!

 
Rep Power: 518

Good to hear it!