How does the EOT Communicate with ECM ??

[HondaLou]

2014 CB1100 Deluxe:  
I've been chasing a problem with my gauges showing I have no oil pressure (I do 70-80PSI), Neutral light always on and Oil Temp light always on.  
I researched the service manual and also replaced all 3 sensors and wire which connects all three of these sensors.  
My question is how do these sensors really get the information to the ECM and gauges?  There is just one common wire harness that connects these 3 sensors.  
How does the "Magic" connection work if there is no wire connecting these sensors to the ECM directly?   See attached photos.         

[Lord Popgun]

HondaLou,
The answer you seek is on the wiring diagram. See the diagram on page 20-6 labeled CB1100SA (AFTER '13 MODEL)

Look at the bottom of the page and find the EOT sensor. Follow the R/Bu wire and it goes directly to the ECM pin B27 and is labeled TO. The G/O wire goes to a junction block to a group of wires that are connected to chassis ground (the one closed to the Horn High symbol)

From the ECU it gets sent by the serial data line to the meter.

For oil pressure the diagram shows it only going to the meters. There is no mention anywhere of it going to the ECU or having a fault code for it. I think that the meter handles that with the light. Either you have pressure or you don't and the light comes on.

I still think you have a meter problem. Could be corrosion inside or maybe a failed meter. IDK

[peterbaron]

....and the wires, including the serial data line, must have a resistance not exceeding 0.5 ohms... The measurement should be taken with the components disconnected to check the resistance of the wire itself, rather than that of the system elements... The cause may be a poor contact that can be remedied by disconnecting and reconnecting the relevant connectors.

[peterbaron]

Besides, this issue has already been discussed here;

https://cb1100forum.net/forum/showthread.php?tid=14715

So, what is the situation after these five months? Was this motorcycle ever modified by the previous owner, were any accessories or anything of that sort installed, any accidents? Or are you perhaps withholding any important information?

[Cormanus]

Isn't your last question a little harsh, peterbaron? Don't you mean something like, "Is there anything else at all that you can tell us to help us diagnose the problem"?

[HondaLou]

So, I spent a lot of time removing corrosion and new chain, polishing, painting and new brake pads and bleeding lines, etc.
I did inspect the wiring diagram and that is the mystery. The R/BU wire and other sensor wires do not exist in this "closed" sub wire assembly. This wire does not go directly to the ECU. There are 3 sensors connected to each other as I show in the photo and no other wires going to these sensors. It is very strange. I checked the Honda schematics as well and sure enough, it shows this common sub-wire assembly connecting the 3 sensors and that is it. The EOT wire in this phots has a Black and green wire and simply dead ends into the sensor. I see no indication of other wires branching off this sub assembly and going to the ECU.

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HondaLou,
The answer you seek is on the wiring diagram.  See the diagram on page 20-6 labeled CB1100SA (AFTER '13 MODEL)

Look at the bottom of the page and find the EOT sensor.  Follow the R/Bu wire and it goes directly to the ECM pin B27 and is labeled TO.  The G/O wire goes to a junction block to a group of wires that are connected to chassis ground (the one closed to the Horn High symbol)

From the ECU it gets sent by the serial data line to the meter.

For oil pressure the diagram shows it only going to the meters.  There is no mention anywhere of it going to the ECU or having a fault code for it.  I think that the meter handles that with the light.  Either you have pressure or you don't and the light comes on.

I still think you have a meter problem.  Could be corrosion inside or maybe a failed meter. IDK

I did inspect the wiring diagram and that is the mystery. The R/BU wire and other sensor wires do not exist in this "closed" sub wire assembly. This wire does not go directly to the ECU. There are 3 sensors connected to each other as I show in the photo and no other wires going to these sensors. It is very strange. I checked the Honda schematics as well and sure enough, it shows this common sub-wire assembly connecting the 3 sensors and that is it. The EOT wire in this photo has a Black and green wire and simply dead ends into the sensor. I see no indication of other wires branching off this sub assembly and going to the ECU.

[peterbaron]

HondaLou,

As per your photo/post # 1

"How does the "Magic" connection work if there is no wire connecting these (3) sensors to the ECM directly?   See attached photos."  

EOP - one wire /ground circuit & NEUTRAL SW - one wire/ground circuit GO to one common 2 pin connector: WPC 2P (Bl) >p.20-6,< and this WPC 2P (Bl) connector IS NOT connected to EOT sensor as you suggest in your picture/post #1

The EOT is a separate circuit = do not mix with EOP & N-SW

1. Connect your sub-harness WPC 2P (Bl) connector to the main harness/match colors*, not to EOT... and let us know
2. Connect,  hanging somwhere, WPC 2P (Bl) G/O-R/Bu colors to your EOT sensor

There are at least four WPC 2P (Bl), but each has different colors = pay attention to connector's colors!!!, you or the previous owner mixed them up, p.20-6

* As per diagram p.20-6, I see two WPC 2P (Bl) connectors but each one has different wire colors.
The main harness side WPC 2P (Bl) has Bu/R & Lg = should match colors of your sub harness P/N 32101-MGC-000

I have to dig deeper to understand and resolve this issue????
I am also concerned of the cluch diode, which is located in the fuse box , p.20-6

[Lord Popgun]

HondaLou,

I see the confusion. First, the way you have things connected in your first pic will not work. Will do nothing and be like that cable isn’t even there as it would not be doing things.

So, you made me go to a parts fiche (I used partzilla) and verified the cable is correct. So now I had to go look at mine as it is wired the same, even though I have a 2013. I’ll say thanks for that as I found the EOP wire out of the little clip.

Anyway I followed the EOP wire to the junction with the neutral switch and then to the end of the cable to the connector you have on the EOT. It actually goes to a connector in a boot behind the right side cover connecting to the wire harness. And my connector is red in the upper boot. You model might be slightly different.

The weird thing is the colors do not match the wiring diagram.

This is a work in progress. I have been trying to follow the EOT wire, but I’m going to have to remove the seat and lift the tank or remove the air box covers so I can see what is going on. So far it comes off the EOT, moves up to the bottom of the left airbox and I THINK it goes over to the right the the connector boots there. More to follow… tomorrow

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PB posted before I did. Thanks PB, looks like your answer is better

[Lord Popgun]

Well, I can’t follow the EOT wire unless I remove the tank as lifting it doesn’t get me anywhere. I’m not doing that as I am not messing around with the aggravating fuel connector.

[MagnaRider]

That fuel connector is a PITA