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Discussion Starter #1
If you have read my newbies post I have a D16a9 engine in the back of my GTM Coupe. It's running a rechipped PW0 ecu and I'm currently tidying up the wiring.

I have made up a diagram, that I think is correct and now in the process of ditching the un-needed connections.

So far I have common-ed up all the ground wires (A2,A4,A16,and A18)
Common-ed up the supply (A12, A13, A14, A15 and B13), I don't run a main relay.

I'm also ditching a few connections as I have no Aircon, a non Honda alternator, no fan relay, no O2 sensor

However a few connections are confusing me.

B1 - Hazard fuse, is this just a live and can be connected to A12 ?
B19 - electric load sense - Whats this ?
C10 - Brake Switch - Why ?

Can anyone help me out with these ?
 

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A12 is for fuel pump. If not using the main relay or a relay that's triggered by the ecu to turn on the pump. It's not needed

C10 isn't needed.
 

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Discussion Starter #4
B1, yes, but how are you going to reset the ECU?

B19, this should connect to the ELD, which, on an OBD0 car, I would recommend you keep.

C10. I'm actually not sure why. LOL!
The ECU will be reset each time, as I have an FIA kill switch that disconnects the battery.

As far a I can see the ELD just tells the alternator to step up the output, as I'm not running a Honda alternator (At the moment I have no alternator, just running on battery power) I don't need it.

C10 maybe for Automatic cars, some form of interlock ? I'll miss it out and see what happens
 

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94 Integra
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Brake switch is usually used for cruise control and/or air conditioning. Most OBD1 systems can use it as a multipurpose input. The ELD may cause a CEL but you may be able to disable it (I'm not 100% with OBD0).

I still HIGHLY recommend automatic control of the fan. Over-cooling the coolant can cause issues. OBD1 systems can be set to turn the fan relay on at a user-set temp, or you can simply use the original thermoswitch to control it. You can always install an override switch in case you want to cool it while in the pits.

Make sure you ground to the block or trans, then adequately ground the block to the frame.

One more thing, you MUST use shielded wire for the 2 distributor signal wires. The shielding (drain) must be connected to ground. Honda usually has a drain on both the engine side and chassis side of the harness for OBD0 & OBD1 cars. This may be even more important depending on how noisy your non-Honda alternator is.
 

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Discussion Starter #6
I still HIGHLY recommend automatic control of the fan. Over-cooling the coolant can cause issues. OBD1 systems can be set to turn the fan relay on at a user-set temp, or you can simply use the original thermoswitch to control it. You can always install an override switch in case you want to cool it while in the pits.
I have a dual thermoswitch in the radiator, along with twin fans that come on at different temps. It's at the other end of the car from the engine (The D16 engine is behind my seat as it's now mid-engined) so a lot easier to wire.



 

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A12 is for fuel pump. If not using the main relay or a relay that's triggered by the ecu to turn on the pump. It's not needed

Please never do this. Disabling the ecu control over the fuel pump is a safety issue. Suppose you get into a horrible crash and the fuel line breaks open, fuel pressure would drop and the engine would stall. This would be a good thing because without a rpm signal the ecu will automatically turn off the fuel pump. However if you run the fuel pump directly off of the ignition switch the first responders might not be able to get to you because will be inside a blazing inferno.

Something to think about. Either way I don't think saving one wire from your harness is worth the risk to you, or your passengers, bystanders, ect.
 

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Love the Civic
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Please never do this. Disabling the ecu control over the fuel pump is a safety issue........
True in a street car. However, if it is a track car, with fuel shut offs in place as required if by-passing relays.....

I have seen your spiel elsewhere though, I fixed my relay and ecu wiring because of this thought process, so I am coming from a place of agreement.
 

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Discussion Starter #10
Please never do this.

Something to think about. Either way I don't think saving one wire from your harness is worth the risk to you, or your passengers, bystanders, ect.
Totally agree for a road car, this is a track car, with compulsory FIA kill switch within reach, even when strapped in with a 6 point harness, and an external pull cable on the bottom of the A pillar that a track marshal/corner worker can reach. The car is also fitted with a plumbed in fire extinguisher, one pointing at engine, one at me.

But considering that the front subframe carries the fuel tank and battery, I try not to hit anything anyway :shock:
 

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93 Legend L Coupe.
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The ECU will be reset each time, as I have an FIA kill switch that disconnects the battery.

As far a I can see the ELD just tells the alternator to step up the output, as I'm not running a Honda alternator (At the moment I have no alternator, just running on battery power) I don't need it.

C10 maybe for Automatic cars, some form of interlock ? I'll miss it out and see what happens
The ELD does more than just alternator control. If you are only running battery, you really need some form of voltage regulation for the injectors and ECU. Running the battery down will greatly change your tune without any form of compensation for the change in voltage.
 

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2 deep cycle batteries and an ultracapacitor setup should easily keep the battery voltage above 12.0 for over an hour of driving.

BUt I agree with beaver. a PC680 will do just fine for cranking and you could grab an alternator from one of the fuel economy models, they use a smaller alternator by I believe 10-15 amps (at least originally. Honda might have updated and simply started using the common models for part number reduction)
 

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Discussion Starter #13
The ELD does more than just alternator control. If you are only running battery, you really need some form of voltage regulation for the injectors and ECU. Running the battery down will greatly change your tune without any form of compensation for the change in voltage.
The average run time is about 30 sec to 2 minutes depending on track.

This is one of the record runs on the hills
 

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Discussion Starter #14
By the end I have it down to 33 Pins, at the ECU
With 18 wire needed through the bulkhead (one screened with 6 cores).
The IMA Pot and Air Pressure (PA) are mounted next to the ECU, keeping the wires to a min.

 

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ELD feature is a Honda feature to use the alternator as a brake while the car decelerates.

Think VERY VERY early regenerative braking. You can very easily disable and not use this feature. No worries.



Make sure you shield the mag pulse sensors/generators from the distributor. Those fuckers pump out massive voltage at higher engine speeds.
 
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