D17VTECPOWER

iTrader: (1)

I recently converted my 2005 Honda Civic's hydraulic power steering to an EPS system from a 2005 Hybrid. The conversion was pretty easy, there was really nothing difficult or overly complicated about it.




Here are the OEM parts that you will need if you would like to convert to EPS:

EPS rack (03 to 05 Hybrid or 02-05 SI EP3)

EPS rack mounting brackets (from whatever car the rack was from)

EPS control module (03-05 Hybrid or 02-05 SI EP3. However, I have heard that the EP3 SI's module is programmed for a heavier steering feel than the Hybrid's module, but I can't say for sure since the only module I have is from a 05 Hybrid)

EPS wiring harness (From whatever car the other parts are from)

(Optional) 60 amp EPS main power fuse and connector to plug into fusebox. You don't need these parts, you can easily connect the EPS main power directly to battery positive with a fuse holder.




Here are the parts you will need to provide for the conversion:

Power wire (I used 8 gauge cable and butt connectors because the system can draw over 40 amps with the wheel cranked to one side. 8 gauge seemed to be about the same size as what Honda used)

Wire connectors or soldering supplies


Electrical tape

Zip ties

Signal wire (I cut some wire out of an old engine wiring harness I had laying around) It doesn't need to be thick, it is just to provide RPM, VSS, and switched power to the module to wake it up, so 22-18 gauge wire will work fine



The actual conversion process: The first thing I did is I changed out the rack and brackets. I removed the intake manifold and installed it from the top. It installs just like a hydraulic rack would, the only difference is that you need to remove the electric motor from the top of the rack before you install it and reinstall the motor once the rack is in the car.




Once the rack is in, you will need to install the EPS module and wiring harness. I cut the harness in half, run the wires through the gromet in the firewall under the passenger side carpet where the OEM harness goes through, and connect the harness back together. I added about 2 feet of extra wire to the harness going through the firewall to make the install easier on myself and neater. There were 6 small wires I extended for the sensor on the rack, and 2 large power wires for the motor that I extended.




Once the harness is in, you will need to mount the EPS control module. I didn't figure out where I am going to mount the module yet, I am thinking under the passenger side carpet's insulation, but I am not sure yet.




As for the wiring you will need to do, there are basically 5 wires you need to connect: Main power (Heavy gauge white/blue cable), Main ground (heavy gauge black cable), Key on power to let the module know when the key is on (thin yellow wire in blue plug), VSS signal so the module knows how much to assist (Thin blue/white wire in blue plug), and an RPM signal so the module knows when the motor is running. (Thin blue wire in blue plug).




I connected the main power to the fusebox. I got the fuse and plug from the donor car, installed the fuse, and plugged the connector into the bottom of the fusebox. Then I just extended that wire to the power wire to the harness inside the car. If you choose to power the system this way like I did, you will need to install a 60 amp fuse in the underhood fusebox in the spot labeled "EPS". Only one of the screw holes is actually threaded, so you will have to use a self tapping screw to secure the fuse on one side, but no big deal.





Obviously the ground just connects to any metal piece of the chassis. The VSS wire goes to the ECU's pin A18, however I chose to connect this wire to the car's side of the C101 connector so I don't have to redo any wiring when I K swap in the future. The RPM signal wire goes to the ECU's pin E26, and the switched power goes to the ECU's pin E9 or any other ignition switched power source.




With the wiring done, start the engine and make sure the steering turns easy before you put the interior back together. If the steering turns easy, you are done! Put the interior back together, clean up the wiring, and go get an alignment.

I hope someone found this information helpful. If anyone has questions, comments, or feedback, please let me know!

thornygravy

This is super dope. Thanks for sharing with us!

Roshem2

Disculpa la energia conmutada q cables son o q color? Saludos y excelent aporte, estoy por hacer ese cambio a mi 7ma

D17VTECPOWER

iTrader: (1)

No hablo español, así que necesito usar un traductor, espero haber entendido correctamente y lo que estoy diciendo tiene sentido. El cable blanco grueso con la franja azul es la fuente de alimentación principal, caliente en todo momento. El delgado cable amarillo en el enchufe azul es la energía conmutada, solo caliente con la tecla encendida. Aquí hay un diagrama si esto ayuda. ¿Esto tiene sentido?

CivicHybrid03

I realize this is over a year old, but ...

I'm curious why you did this - is the EPS system superior to the hydraulic system in some way?

I'm new here and new to Honda cars, so I haven't read up on this yet.

Thanks!

BrotatoChip

EPS is more efficient than hydraulic. Running a hydraulic pump all the time induces parasitic loses on the engine. EPS only works when needed reducing the load. Also, EPS has no fluid to leak or maintain. Below is a notice from Honda stating the EPS system in the EP3 improved fuel economy by 2%.

https://hondanews.com/en-US/honda-au...assis?page=111

D17VTECPOWER

iTrader: (1)

Welcome to the forum!
Yes, EPS is superior to hydraulic power steering because it is much more efficient. The hydraulic power steering system uses a belt driven hydraulic pump that is mounted to the engine to send pressurized fluid to the rack. The problem is that the engine is always spinning the power steering pump even when driving in a straight line and assist is not needed, creating drag on the engine for no reason. This results in higher fuel consumption and less power to the wheels. People have reported gains of around 3 horsepower and 1 MPG from getting rid of their hydraulic power steering. Electric power steering take power from the engine as well through the alternator, but only while actually turning the wheel instead of constantly.

There are other benefits as well. The EPS system is a lot less bulky since it doesn't need a pump, reservoir, or hydraulic hoses, making it a few pounds lighter too. The EPS system just has a motor on the rack behind the engine and a control module inside the car with some wiring. It's also nice to have one less fluid to worry about.

CivicHybrid03

Ah - makes perfect sense - thanks, gentlemen.

I'm pretty sure my '03 Hybrid has it, so I'm good.

Thanks for the welcome, D17VTECPOWER.

V8Fettler

Thats awesome, you seem to know your stuff. I don't suppose you have any access to the format which the engine/rpm signal is?
And, do you know if the system works without it?
I'm trying to use this setup in a classic car, so I can replicate the wheel rotation signal easy enough, butthe engine RPM signal I could do with knowing the format.

Ideally, knowing if the system still works with just the speed signal and power supplied would be good!

Thanks

D17VTECPOWER

iTrader: (1)

I do not know what format the engine speed sensor signal is in. I would check it for you it but I don't have a scope. The system needs the signal to turn on though, so you would need to figure something out to simulate the signal. The EPS doesn't activate with the key on until the engine is running, but once it is on if I kill the engine without shutting the key off the EPS still continues to work until the key is turned off.

I don't think the module uses the RPM signal for anything but as a signal to turn on though, so if you create some kind of electronic circuit to simulate an RPM signal it should work fine. Makes me wonder why they didn't just set the module up so it turns on when the key is on.

I hope this helps. If you have any other questions feel free to ask!

BrotatoChip

The engine speed signal is almost certainly a 5V square wave. At what frequency, I'm not sure.

Shamgod

Hey! Beautiful write up. I’m in the middle of doing this conversion and have a question. Did you pull anything out to plug in the power plug right into the fuse box? It seems that I already have something (red/white wire) plugged into the same place you put yours. Did you also have this? And if so do you know what that wire is for? Thank you!

D17VTECPOWER

iTrader: (1)

Welcome to Civicforums! I don't know what the white and red wire powers, my 05 LX sedan doesn't have it but my friend's 01 EX coupe and the plug I got from the Civic Hybrid did. Does yours have ABS by any chance? That's the only thing I can think of that it might power since my LX doesn't have ABS or that wire and my friend's EX and the hybrid does.

If you have the plug from a Civic Hybrid or EP3, I'd try to pop the terminal with the white and blue wire out of it and put it into your plug, it will probably fit fine since the white plug's housing is likely the same. Running an 8 gauge or heavier copper wire directly from the positive battery terminal through an external 60 amp fuse to power the EPS system will also work fine.

Shamgod

Thank you for the welcome and quick reply! I do have the EX, from the shop manual it seems to be part of the engine harness or EDL, nonetheless it has to stay in. I do have the plug from a whole ep3 harness. Are you sure I could just pull it out and reattach it to the one that’s already in the fuse box? I would just put it into the slot next to the red and white one? And if so I still just put the fuse into the eps fuse spot right? Was hoping I could figure it out with what I have instead of having to recut the wire and solder again for an external fuse.

D17VTECPOWER

iTrader: (1)

I haven't tried to do that on this plug specifically since mine didn't have the red wire, but I have repinned many other similar connectors before. There's generally a little plastic lock tab inside the connector you need to push down on with a pick, small screwdriver, etc while pulling the wire out of the connector. Sometimes it's a pain and you have to mess with it for a while before it will come out.

Once you get it out of the EP3 harness, yes, you would push it into your original plug in the slot next to the white and red wire. It should snap in and be secure if you have it in the right direction. If it doesn't go in or lock in place, flip the white and blue wire 180 degrees and try again.

Shamgod

I wasn’t aware that the connectors worked that way, that’s good to know though learn something new every day. I’m just gonna cut the wire below where I soldered the extension and just put the wire into the already existing plug that way. Thank you so much for the guidance man I appreciate it 🙏 By any chance would you happen to have a picture of which exact grommet you cut into as well?

D17VTECPOWER

iTrader: (1)

I'm glad I was able to help. You can run the wires through any of the grommets or even drill a new hole and use your own grommet if you prefer, just make sure the grommet seals reasonably well and the wires can't rub on anything that could damage them. I used the grommet the interior harness runs through at the very bottom of the firewall on the passenger side, the same grommet the rest of the wires from the fusebox go through.

Shamgod

That's the same one I was planning to use, pictured below for reference from the bay and the inside. Did you end up having to cut the grommet to be larger for everything to fit or all the wires fit through tightly? And yeah I could really use an engine bay cleaning lol

D17VTECPOWER

iTrader: (1)

I couldn't say for sure whether you would have to cut the grommet or not. I moved my battery to the trunk years ago and had to cut the grommet to run the positive cable through, so I just ran my wires next to the battery cable that I already ran through. When I was done, I sealed around the wires the best I could with black RTV silicone to keep moisture, wind, heat, and noise from coming into the cabin through the gaps around the wiring.

BrotatoChip

That large white/red wire is for ABS. I did exactly as @D17VTECPOWER is mentioning, removing the white/blue wire/terminal and inserting into the original connector next to white/red. I went a step further and opened up the fuse box to add a nut. This way the 60A fuse is held down with the same screws as the others, no self tapping screw. Makes it look even more OEM.

Shamgod

That’s how I ended up doing it today, thank you for clarifying! Connected all the wires but it doesn’t work. Thinking I may have tapped into the ECU incorrectly. Based on this video there’s two different wiring harnesses, one with green wires and the other with blue. Does anyone know where each harness would come from and what makes the difference? Is it a certain year? I got mine from a 2002 ep3.

https://youtu.be/cdvzTqkObM0

Mine were a lil faded so I think maybe I may have confused the blue and green since it was hard to determine the color. Spent ten minutes trying to determine and decided green it was. Either that or I’m not drawing power. Gonna try to figure it out tomorrow

D17VTECPOWER

iTrader: (1)

Your best bet is to verify that the wiring is correct using the control module pinout in post number 4 since (to the best of my knowledge anyways) the EPS module's pinout is the same on all the EP3's and 03-05 hybrids. Also, verify that you have power at the module on the large blue/black wire at all times, power at pin 10 when the key is on, and a good ground at the large black wire.

If that doesn't work, you can connect a small LED to the wire coming from pin 6 get the blink codes to see what errors the module has stored and clear them if needed. Any error codes will disable the EPS system until you clear them and the codes are stored in non volatile memory, so disconnecting power won't clear them.

Shamgod

You’re the best man thank you for the troubleshooting, was completely lost and you just set me back on path. I appreciate you 🙏 Few questions though since I’m still getting familiar with electrical. How do I check if there’s power at the wire if it’s insulated? Is there a specific tool that would work for these small wires or would I have to cut the rubber? Also how do I go about connecting the LED to pin 6? Do I just plug it into the socket pin and turn the car on? I’m gonna go by the following order, writing out a list so I could refer to it sequentially when I get back to the car:

1) Double check ECU wire taps are correct from the pin out.

2) Make sure black wire is grounded well.

3) Double check power wire source and then check if there’s power at all times at the large blue/black wires at the module.

4) Make sure there’s power at pin 10 when the key is on.

5) Use a small LED to connect to the pin 6 wire and read any error codes.

D17VTECPOWER

iTrader: (1)

I'd check for power using an incandescent test light connected to ground and check for ground using a test light connected to positive. You can use a volt meter too, but this can be misleading sometimes if there's a voltage drop or poor connection.

Don't poke the wires or cut the insulation off for testing, you can check for power and ground at the module by either unplugging the connectors and using a test light or volt meter on the plug's female terminals or by touching it to the exposed metal of the terminals in the back of the plug next to the wire. Just be careful to not shove anything into the female terminals with force because you can spread them out and cause a bad connection. If you are having trouble touching the pins with the probe, you can use something thin like a small paperclip or pin to touch the terminals with.

If needed, you would connect the positive side of the LED to a 12V power source and the negative side of the LED to the wire coming from pin 6. Once the LED is in place, turn on the ignition. The LED should be lit. Then start the engine. Once the engine is running, the light should go out. If it stays on, there's codes stored in the module. To pull the blink codes, you would need to ground out the wire coming from pin 8 to make the light start flashing.

That list looks good to me. How did you connect the EPS wires to the car's harness? Hopefully you crimped or soldered them instead of using those plastic wire taps you put both wires in and squish down?

Shamgod

Sounds good, thank you again for the detailed walkthrough. I think I have one of those test lights somewhere at home. A lil confused on the LED part still and how to connect that to power but I’ll look over the wiring and pin diagrams again to try to figure it out.

I did use the plastic t-taps that you have to squish down. Might have to remove them and strip the insulation and then just twist and solder from there if I hooked it up wrong.

BrotatoChip

I used that style of taps once without any luck, never again.

Shamgod

Hey guys, just an update. Turns out I had the ecu taps switched. Confused the blue with green since the wires were faded and ended up switching the vss and nep by accident. Followed the pins and the wiring diagrams to make sure everything connected correctly and double checked everything on the list from above ^. Wanna thank everyone again for their help. Got it working today and the steering is so light and easy feels like a brand new car. Seems like the road feel is lacking a bit compared to hydraulic but that was expected, loving how empty the engine bay is now. Can’t wait to see what it’s like at high speeds after I get the alignment.

Shamgod

They’ve always worked for me, used it for my back to camera and now the eps and it’s held strong so far.

D17VTECPOWER

iTrader: (1)

Awesome, glad you got it figured out! I know what you mean about the EPS lacking some road feel. I also feel like it's a little sticky at times like it doesn't center itself great after turning the wheel and has to be centered manually, but that might just be my specific rack. It feels great to me around tight turns though, maybe even better than the hydraulic system. But it's hard for me to compare the electric and hydraulic systems directly because my hydraulic system was broken for over a year before I decided to get the EPS system and I was driving it with the pump and lines removed, so I didn't drive them back to back.

BrotatoChip

There is definitely a different feel to the EPS. Mostly when in a parking lot or backing into the garage where the wheel is turned back and forth quickly. While actually driving, I have a hard time feeling much of a difference at all.