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Discussion Starter #1
I'm trying to add an LED to signal when my EX's R18 goes into econ mode. I've got a thread in the sedan forum on the subject if your interested in more details.

I've found the wires going into the solenoid. Unfortunately there is no slack in the connector wiring and it's in the back pass side of the engine and down pretty low so i cant tap them closer to the connnector. I traced the wires into a bundle on top of the motor. They run into a bundle that passes through a plastic cover right behind the valve cover. Problem is that there are two wires in this bundle that match the wire colors I found going into the three wire connector (so there are six wires matching the three wires going into the connector - 2 each).

The connector has one white wire with two black stripes, one green wire with two yellow stripes and one blue wire with two yellow stripes.

My guess is that the white wire is a ground and the two colored wires engage the solenoids.

so my questions- 1. can someone with a fsm be so kind as to look up the vtec solenoid wiring on and tell me what wire does what. 2. can you confirm if both the matching wires in the top bundle are the same or different.

OK, I've finally found the diagram I was looking for, which is less confusing. Unfortunately, it looks like the color can vary by year. What year is your car?

More specifically, it looks like the blue/yellow and green/yellow lines are for the oil pressure sensor. From this I'm guessing you have an 07 or later because my manual (covering 06 and 07) indicates the 06 uses different colors.

As stated before the signal line for the solenoid is black/white, but this other diagram says the ground is just black. Since you don't mention a black line, I'm not sure what to make of this. Maybe there's a line going to the body or block that you're not seeing?

Again I apologize for being scattered on this. It was a long day at work and I'm trying to do a bunch of things right now -- but I'm eager to help if I can because I've thought about doing this to my car many times!
 

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FSM says:

Name: VTS (rocker arm oil control solenoid)
Description: Drives rocker arm oil control solenoid
Terminal 34 on Connector B
Wire color: BLK/WHT
Signal: about 0 volts at idle


Does this match what you're seeing? This came from a diagram of the connector, I assume the wires go all the way through.

I'm very interested in your progress here, FWIW.
 

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A little more detail:

The FSM has a diagram showing two wires leaving the solenoid. Could the third wire you're seeing be going to the oil pressure sensor near the solenoid?
 

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OK sorry, I'm a little scattered tonight. More info:

The FSM also lists a wire going to terminal 33 on connector B called SG2, Signal Ground 2, which is GRN/YEL. I'm guessing this is the ground wire going to the solenoid. Presumably when economy mode is engaged you'll get voltage between the BLK/WHT line and the GRN/YEL one.

Still not positive what the other one is. Will post back if I can find it.
 

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Note there's a wire on the same connector that's WHT/BLK that goes to the IMT system. The FSM says this is the IMT ground, and should be 4.5 volts with the ign in position 2. Sounds like this could be confused with the VTEC solenoid control line. You sure the line you're seeing is going to the solenoid?
 

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OK, I've finally found the diagram I was looking for, which is less confusing. Unfortunately, it looks like the color can vary by year. What year is your car?

More specifically, it looks like the blue/yellow and green/yellow lines are for the oil pressure sensor. From this I'm guessing you have an 07 or later because my manual (covering 06 and 07) indicates the 06 uses different colors.

As stated before the signal line for the solenoid is black/white, but this other diagram says the ground is just black. Since you don't mention a black line, I'm not sure what to make of this. Maybe there's a line going to the body or block that you're not seeing?

Again I apologize for being scattered on this. It was a long day at work and I'm trying to do a bunch of things right now -- but I'm eager to help if I can because I've thought about doing this to my car many times!
 

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Discussion Starter #7 (Edited)
wow- this is great. I really appreciate the help.

From what I've read, there are three solenoids (this could be wrong for all I know). From outside appearances, it appears that there are two. There is one on the top (and much easier to access) that one has two wires going into it. As I recall they are both black - one with a white stripe. The other solenoid looking thing is the one I was asking about. It is down low and has three wires going into it (which I'm guessing means that there are 2 solenoids or sensors in the housing somewhere).

Here's a pic of the solenoids I was able to find: Solenoid picture. The whole assembly is located just behind the valve cover on the pass side. The top solenoid is easily accessible. http://www.hondatuningmagazine.com/tech/0704_ht_r18_engine/photo_18.html

I did some testing on the top one because it was easy to access. I connected my volt meter to the two wires. I assumed one was 12v+ (at least went getting a signal from the ECM) and the other was a ground. I did not have the connector plugged into the solenoid during this test as just pushed the wires pushed into the connector terminals rather than cut into them for the test. I think that may have been the flaw in my test as I suspect the ECM knew this and did not react as I was expecting. From the time that I turned the car on, to the point that I turned is off- regardless of engine speed, gear etc. I got a reading of between 3.2v and 3.8v. This did not change below 1000-1500 rpms (where I expected 0volts) of from 1500-3500 (where I had hoped for 12v when being easy on the gas). I did notice that when I went above 3500rpms, the engine stumbled. This scared the crap out of me and I backed off immediately to make sure I didn't screw anything up.

Based on what you've found, it sounds like the top one is the one I need to tap because it's the one with the two black wires. The bottom one, with the green, white and yellow, wires appears to be a set of pressure sensors.

I think I need to do another test - but this time with the connected plugged in and see what I get.

Btw- my car is a 2008.
 

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OK, I think this is making more sense now. I think I can recall reading an article before that mentioned that the R18 has 3 VTEC solenoids, but I'm pretty sure this is not the case -- it only has 1. The FSM and other docs online that detail its iVTEC operation show that it only has 2 modes (not 3 like the SI, the hybrid, and probably other past models). Moreoever the FSM mentions only one rocker arm oil controll solenoid. So:

- The top one with 2 wires going into it is the VTEC solenoid
- The bottom one with 3 wires going into it is the oil pressure sensor (probably used to override VTEC operation when oil pressure is too low to effective turn it on)

VTEC should be "on" when under light load between 1500 and 3500 RPM -- i.e. when you're in "economy" mode. The pure BLK wire should be the ground and should be close to 0 volts at all times. I believe the voltage between the BLK/WHT and the BLK lines should be around 5 volts when VTEC is "on" and 0 when it's not (e.g. at idle). I don't think it runs off 12 volts, but I could be wrong. EDIT: I will try to remember to check this in the FSM when I get home.

Please note that I have very limited electrical experience, so take this info with a grain of salt and definitely do your own careful tests (sounds like you're already doing that)!

If you need further info let me know and I'll check the manual again when I get home tonight.

I'm looking forward to hearing about the results of a second test. What you were seeing before (high voltage at idle) seems strange.
 

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Discussion Starter #9
OK, I think this is making more sense now. I think I can recall reading an article before that mentioned that the R18 has 3 VTEC solenoids, but I'm pretty sure this is not the case -- it only has 1. The FSM and other docs online that detail its iVTEC operation show that it only has 2 modes (not 3 like the SI, the hybrid, and probably other past models). Moreoever the FSM mentions only one rocker arm oil controll solenoid. So:

- The top one with 2 wires going into it is the VTEC solenoid
- The bottom one with 3 wires going into it is the oil pressure sensor (probably used to override VTEC operation when oil pressure is too low to effective turn it on)

VTEC should be "on" when under light load between 1500 and 3500 RPM -- i.e. when you're in "economy" mode. The pure BLK wire should be the ground and should be close to 0 volts at all times. I believe the voltage between the BLK/WHT and the BLK lines should be around 5 volts when VTEC is "on" and 0 when it's not (e.g. at idle). I don't think it runs off 12 volts, but I could be wrong. EDIT: I will try to remember to check this in the FSM when I get home.

Please note that I have very limited electrical experience, so take this info with a grain of salt and definitely do your own careful tests (sounds like you're already doing that)!

If you need further info let me know and I'll check the manual again when I get home tonight.

I'm looking forward to hearing about the results of a second test. What you were seeing before (high voltage at idle) seems strange.

Great. Let me know what you find in the FSM in terms of voltage. I'm wondering if the 3+/-volts I was getting was some sort of error/limp mode reading because the ECM detected that the solenoid was out of the loop (ie maybe the resistance level was out of spec). I think I'll try to tap the black w/white strip and use another ground and see what I get.
 

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Discussion Starter #10
Success!!

I got it working! Many thanks to Rationull for his help with identifying the solenoid wiring. I've been searching for info on the vtec wiring for some time now and took a chance on this section of the forum.

So the details- based on what Rationull found in the FSM, I was able to connect a standard 12v LED such that it lights up when the motor goes into econ/i-vtec mode.

For the test I wired the positive side of the LED to the black wire w/white stripe that connects to the solenoid located on the top, back side of the motor. See my earlier post in this thread for a picture of what I'm talking about. I connected the neg side of the LED to a ground.

I went for a short drive and exactly as I had hoped, when the motor is between 1000 and 3500 rpms, it will enter i-vtec. This only happens when certain conditions are met. These conditions appear to be at least:
1. the motor is up to operating temp
2. there is some opening of the throttle (ie coasting disengages it)
3. you are very light on the gas peddle
4. in third gear or above
5. no breaking (i tried to test using the breaks while keeping pressure on the gas).

I'm sure there are other criteria but these are what I gathered in my 10 min drive. I also noticed that now that I have the light signaling the cam profile change, I can actually feel a very slight change in the engine power under certain conditions - mostly when in 3rd/4th gear when i-vtec dis-engages.

For the time being I've got the LED zip-tied to the driver side windshield wiper. This weekend I plan to add a relay and resistor to the system and run the signal wire through the firewall so I can install the LED somewhere in the dash. I'm a huge stickler for things looking as though they came from the factory so I will need to spend some time thinking about where exactly I want to put the LED.

I plan to do a mini DIY on this over the weekend. I'll snap some pics in the process.

Thanks again for the help!
 

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It probably doesn't matter anymore but all I can find in the FSM with respect to voltage on the solenoid control line is the "0 volts at idle" I posted above. Do you know whether you were getting 12 volts at the LED vs 5 or something else?

Interesting observations. In particular "3rd gear or above". I assume that means you have an AT?

I'm very interested in your DIY. I've thought about doing this before because I'd love to know when the car's in econ mode. I feel like I can tell when it switches but I'd like confirmation and I haven't been able to figure out how to get that info through the OBD2 port. The major thing blocking me is figuring out a way to mount the light that doesn't look like crap, and as we all know the Civic's engine bay isn't exactly the most accessible.

Looking forward to more updates!
 

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Discussion Starter #13
It probably doesn't matter anymore but all I can find in the FSM with respect to voltage on the solenoid control line is the "0 volts at idle" I posted above. Do you know whether you were getting 12 volts at the LED vs 5 or something else?

Interesting observations. In particular "3rd gear or above". I assume that means you have an AT?

I'm very interested in your DIY. I've thought about doing this before because I'd love to know when the car's in econ mode. I feel like I can tell when it switches but I'd like confirmation and I haven't been able to figure out how to get that info through the OBD2 port. The major thing blocking me is figuring out a way to mount the light that doesn't look like crap, and as we all know the Civic's engine bay isn't exactly the most accessible.

Looking forward to more updates!

I'm not sure what the voltage output is at this point. I did test the LED on a 6volt battery before I started to ensure it would light under lower voltage situations. I did this due to one of your earlier posts where you thought it might only be a 5v signal. Up to that point I had been assuming 12volts - and I didn't want to discount the test because the LED didn't work under low voltage situations- that would have been a waste of time.

I think the really cool thing about this is that you only need to get one wire into the cabin. This makes it very easy to make everything look stock- both in the engine bay and inside the cabin.

To ensure the maximum possible factory appearance, I tapped into the wire inside of the plastic channel that runs behind the valve cover. There are two screws and a bunch of tabs that need to be removed/opened. Once this is done (the tabs are a pain to open btw) you can easily trace the black w/white wire inside the channel and tap it in there. This also protects the joint- so there is no chance of it working loose etc.

I then ran my wire out the driver side of the plastic housing. This places the wire very close to an opening in the firewall that I can route the it through when I do the permanent install.

Another observation I found on my way to work today was that when you get up to about 70-75mph, it becomes increasingly difficult to keep in the econ mode. A very slight incline in the road or small change in pedal pressure causes it to disengage. At lower speeds like 55-65mph- where I'm usually traveling, it's much easier to keep in econ mode - even if you need to add a bit of gas.

I've got a Scangauge attached to my OBDII port. I love the data I can get from it but I was not able to come up with a way to have it report that i-vtec was in or out. Also, I'm not sure I'd want to give up any of the 4 metrics I'm tracking now (as an aside, I've love to have a SG venison that would display 8 metrics at once).

Also, my car is a 5MT so that makes it easier to do the gear tests.
 

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Interesting. I figured maybe you had an AT because of the third gear observation -- I didn't think the ECU had any way of determining what gear the transmission is in on the MT car. I was going to ask you about speeds though, so I'm glad you have an MT because that means the data applies to my car too :)

I was actually going to ask about what speeds on the highway would allow you to stay in econ mode. Getting up to 70 you hit increased wind resistence and with 75 you're getting close to the 3500 RPM boundary so it doesn't surprise me that it's hard to keep it in econ mode at that speed. Good to know that you can keep it in econ mode at 55-65 even with a little gas, though -- I drive 60-65 most of the time.

You only need to get one wire into the cabin, I assume, because you're grounding the LED to an in-cabin ground? And did you have to take the cowl cover off to get at the wires on the backside of the engine or were you able to squeeze in without removing it?

I've got a SG too. Out of curiosity, what do you monitor on it? I tend to monitor trip average fuel economy (added as an XGauge), voltage, load or TPS, and sometimes coolant temperature when I feel like it. I've tried to use it to figure out when I'm in econ mode by monitoring MAP and TPS but I can't get a good read on what numbers to look for because I have no other reliable indicator. That's where the light would come in.

FYI you can daisy chain two SGs together and read 8 parameters, IIRC. Obviously that's twice as expensive as one SG :)
 

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Discussion Starter #15
You are correct on the one wire thing. Since I will be grounding somewhere inside the cabin, I just need to get the positive lead inside- should be very easy.

I went to Radio Shack at lunch and picked up a relay, some resistors and fuses. I expect I'll get everything done this weekend.

If I understand your question right, I had to take the two screws off the black plastic wire cover. This was the only way I could open it. You could avoid this whole step if you're willing to tap the wire after it exits the housing. There is prob 3-4 inches of wire there. I just really wanted to keep it clean looking so I followed the leaded into the housing. I think this also serves to protect the connection as well.

Re: the scangauge- I've settled on tracking RT MPG, RT gallons per hour gas consumption, engine/coolant temp and LOD.

I need to see if mine has the x-gauge add-on. I got it early last year and from what I've read, the x-gauge stuff was added in 2007. If I got an old stock version I may need to send it in. What are some of the other things I can track via the x-gauge codes. Also, do you know how I can determine if I've got the x-gauge controls? Lastly, if I do have it, I'd love to know what the codes are for trip MPG. Is there a list of R18 codes somewhere.

Funny about the two SC's. I take enough crap from people over having just one in my car. I can only imagine what they would say if I added another. :)

Where do you have your's mounted?
 

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I was actually asking whether you had to take off the plastic piece at the bottom of the windshield, between the wipers, in order to get enough space to work on the back of the engine. I get the part about the wiring cover back there.

To check if you have XGauge, go to the home screen and hit "More" 3 times. If you do, the top right menu option should be "XGauge" where you can enter the gauges as described on the SG website. The top left option on that final menu screen is "Version" and I believe XGauge is included in version 3.15 and up.

The top link on ScanGaugeII - Add-A-Gauge gives you some XGauge setups and lower on that page, the "Displaying a Trip Value as an XGAUGE" link shows you how to display any trip computer value on the main gauge screen. I've found for my normal commute I like displaying trip average MPG rather than instantaneous MPG because it's less distracting and less variable to road conditions (lots of slight uphill around here), but still lets me tune my commute for max MPG if I want to.

I'm not aware of any really cool Honda codes -- the SG site has a bunch of codes for Ford, GM, and Toyota vehicles though. The scanguage forum at CleanMPG might have some interesting codes, but I'm not sure.

And yes, I noticed out post counts are pretty close.
 

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Discussion Starter #19
I was actually asking whether you had to take off the plastic piece at the bottom of the windshield, between the wipers, in order to get enough space to work on the back of the engine. I get the part about the wiring cover back there.
Gotcha- nope- I didn't take that off. Once I took the two machine screws that attach the cover to the motor, I was able to rotate it 90 degrees such that I could get the tabs opened. Once opened, I pulled off a bunch of the electrical tape so I could release about a foot or so of the two wire connector. I them made the tap, re-taped everything and put things back together - prob 30 mins total.

Space is definitely a tight (I've got relatively big hands too) but I'm guessing it was still easier than going to the trouble of taking the covers off the wipes etc.

I'll take a look at the SG stuff. Thanks for the info.
 

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Discussion Starter #20
Final install complete

I finished the install over the weekend. I'm still working on a min-DYI. I'm very happy with how it turned out. I think it looks very 'factory'. I bet almost nobody driving the car would ever think otherwise. Based on the last few days, I think it will be a very useful tool when trying to achieve the best possible gas mileage.

Until I get the DIY complete, here is a quick pic of the light in action:


Sorry for the poor pic quality, it's hard to drive at night, snap a picture and not kill yourself all at the same time....
 
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