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Discussion Starter · #1 ·
Hi all, I am new to the forum and hoping for some help. I have an 04 cry and code P2646 popped up. So the first thing I did, from a suggestion on line was pulled off the Vtech selonoid and cleaned the screen filter and changed oil. But I didn’t have correct oil, I used 5w30 synthetic, 4 qts and topped off with reg 5w30, because that is all I had. I also just drained old oil out of filter and put back on because I didn’t have a new one.
that didn’t work, so I bought new vtech selonoid that had new oil pressure switch with it, but after a few miles code came back on and had same symptoms when driving.
so I was going to change oil/filter with correct oil?
could that be issue? Is it that sensitive, that wrong oil could cause?
thanks for any feedback
 

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I think there are a lot of people that will blame the oil weight and will insist that must be done for the vtec solenoid to work correctly.

so now that you have a repeat p2646, I would be frustrated. Is your new solenoid bad? Is it the oil weight? Or do you have another issue such as a wiring break?

I personally would look for other potential causes. I went through the factory service manual a few years ago on the p2646 for an 03 element (should be the identical engine to the 04 crv) which had a pretty decent, straightforward diagnosis algorithm.

Apologies, I don’t have that information anymore.

It certainly went through oil level checks, wiring checks, oil pressure checks, pressure switch check, and solenoid check - to tell you what is the cause of the mil. I replaced with an new aftermarket solenoid which lasted 1month until it flashed a p2647. the pressure switch on the new solenoid went bad. Being pissed at myself for not going with a Honda part, a friend told me he had a known good, “used “ Honda solenoid off of an 02 crv from his niece, that he unnecessarily changed out because he changed the part before testing anything. I installed that, and would up getting an intermittent p2646 on only when it rained (wtf?), plus a very slow oil seep from the gasket area. After swapping out the gasket twice with new Honda gaskets, and searching for months trying to find some intermittent wire issue that might have been caused by rain, no change. I gave up and put in a new Honda original part, and no more mil, no more leak.
 

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Discussion Starter · #3 ·
I think there are a lot of people that will blame the oil weight and will insist that must be done for the vtec solenoid to work correctly.

so now that you have a repeat p2646, I would be frustrated. Is your new solenoid bad? Is it the oil weight? Or do you have another issue such as a wiring break?

I personally would look for other potential causes. I went through the factory service manual a few years ago on the p2646 for an 03 element (should be the identical engine to the 04 crv) which had a pretty decent, straightforward diagnosis algorithm.

Apologies, I don’t have that information anymore.

It certainly went through oil level checks, wiring checks, oil pressure checks, pressure switch check, and solenoid check - to tell you what is the cause of the mil. Mine at the time turned out to be the solenoid. I replaced with an aftermarket part which lasted 1month until it flashed a p2647. This time the pressure switch went bad. Being pissed at myself for not going with a Honda part, a friend told me he had a known good, “used “ Honda solenoid off of an 02 crv from his niece, that he unnecessarily changed out because he changed the part before testing anything. I installed that, and would up getting an intermittent p2646 on only when it rained (wtf?), plus a very slow oil seep from the gasket area. After swapping out the gasket twice with new Honda gaskets, and searching for months trying to find some intermittent wire issue that might have been caused by rain, no change. I gave up and put in a new Honda original part, and no more mil, no more leak.
Thanks, I went out and checked wiring and it doesn’t seem I am not getting power to the oil pressure switch on the vtec selonoid unit. there are 2 connections there, one for the selonoid and one for the rocker arm oil pressure switch. I disconnected it and with ign on engine off, (2 wires to this connector) I had no power to bl/black or maybe it’s just black. So then I hooked up light to positive on battery and tested gr side of connector(yellow/gr) and I do have good ground. I should have power there with ign on/engine omg. no Power with engine on either.?? Pretty sure I should have power there.
so to me, it seems I have a break in wire someplace? Is there a fuse maybe for this? I looked in fuse box under steering column and in engine compartment and couldn’t find one?
thanks for your feedback on Easter!
 

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Discussion Starter · #4 ·
Thanks, I went out and checked wiring and it doesn’t seem I am not getting power to the oil pressure switch on the vtec selonoid unit. there are 2 connections there, one for the selonoid and one for the rocker arm oil pressure switch. I disconnected it and with ign on engine off, (2 wires to this connector) I had no power to bl/black or maybe it’s just black. So then I hooked up light to positive on battery and tested gr side of connector(yellow/gr) and I do have good ground. I should have power there with ign on/engine omg. no Power with engine on either.?? Pretty sure I should have power there.
so to me, it seems I have a break in wire someplace? Is there a fuse maybe for this? I looked in fuse box under steering column and in engine compartment and couldn’t find one?
thanks for your feedback on Easter!
Oh, I didn’t re read my email. The first sentence should say, “ it doesn’t seem I am getting power to the pressure switch”. Sorry
 

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Discussion Starter · #5 ·
Oh, I didn’t re read my email. The first sentence should say, “ it doesn’t seem I am getting power to the pressure switch”. Sorry
I saw on a youtube that a guy used a voltmeter to check power going to pressure switch but a light to check ground side. Can’t I use a light on both sides or is there something I don’t understand about that?
 

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Thanks, I went out and checked wiring and it doesn’t seem I am not getting power to the oil pressure switch on the vtec selonoid unit. there are 2 connections there, one for the selonoid and one for the rocker arm oil pressure switch. I disconnected it and with ign on engine off, (2 wires to this connector) I had no power to bl/black or maybe it’s just black. So then I hooked up light to positive on battery and tested gr side of connector(yellow/gr) and I do have good ground. I should have power there with ign on/engine omg. no Power with engine on either.?? Pretty sure I should have power there.
so to me, it seems I have a break in wire someplace? Is there a fuse maybe for this? I looked in fuse box under steering column and in engine compartment and couldn’t find one?
thanks for your feedback on Easter!
sorry, too long ago for my brain. I don’t remember any wiring details to help you confirm what the wires are. I do not remember doing any fuse testing. if you’re not finding stuff on YouTube or the internet, you might have to get the info off of Mitchell or splurge and find a copy of the service manual off of eBay or something.

heres a thread from the element website. I’m not sure how much it’ll help you, but there’s one guy named “Honda tech” that has contributed a lot to how the system works. You may pay particular attention to his posts.

 

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Discussion Starter · #7 ·
sorry, too long ago for my brain. I don’t remember any wiring details to help you confirm what the wires are. I do not remember doing any fuse testing. if you’re not finding stuff on YouTube or the internet, you might have to get the info off of Mitchell or splurge and find a copy of the service manual off of eBay or something.

heres a thread from the element website. I’m not sure how much it’ll help you, but there’s one guy named “Honda tech” that has contributed a lot to how the system works. You may pay particular attention to his posts.

Thanks
 

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The oil switch on the solenoid assembly is the only one that you can easily test. The solenoid itself the computer engages.

There is also a solenoid on the front (would be passenger side) of the engine. 1 10mm bolt and just look for the wires plugged in just above the drive belt. Thay also has screens and will cause all kinds of havoc with the vtech as its part of the system. Not just the assembly on the back corner of the engine.

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Discussion Starter · #9 ·
The oil switch on the solenoid assembly is the only one that you can easily test. The solenoid itself the computer engages.

There is also a solenoid on the front (would be passenger side) of the engine. 1 10mm bolt and just look for the wires plugged in just above the drive belt. Thay also has screens and will cause all kinds of havoc with the vtech as its part of the system. Not just the assembly on the back corner of the engine.

Sent from my SM-N975U using Tapatalk
the first thing I need to do is find out why I don't have power to the oil pressure switch on the vetch solenoid assembly. it seems as though I should have 12v on one side and gr on other, with connector off, ing on/engine off. I don't have any power there. I think that is the problem, but I don't know how to approach it? there must be an easier way than digging into the wiring harness. If I knew where the power wire came from I could check for continuity from pt A to B. Does it go to the computer and would it be easy to find.
Boy, I would buy someone a few beers if I could get some help with this issue. thanks
 

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Actually I dont believe there is power to the switch, it is a ground based switch if I recall correctly. Even then, you would get 5v if there was power not 12v. Which a cheap test light may not work with.

My brain is slow to remember right now, just had a tooth removed last night and wasnt a fun one.

Give me a bit, I will look up the wiring for that switch when I get a chance (I'm a tech and at work now, just have to get in front of a computer)

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Looking at the diagram right now, what I thought, no power, switch makes ground contact only using supplied ground wire. So ignore that.

Solenoid has a power and ground supplied by the computer

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Discussion Starter · #12 ·
Looking at the diagram right now, what I thought, no power, switch makes ground contact only using supplied ground wire. So ignore that.

Solenoid has a power and ground supplied by the computer

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Well, I’ll change oil and filter with the right stuff and try again. Thanks
 

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I decided to search videos on the subject, this guy rambles a bit, but does the best job of explaining the system I’ve seen. Admittedly I think I had to watch it 4 times before it started to make sense. By the way, there is a part 2 to it.


 

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Discussion Starter · #14 ·
I decided to search videos on the subject, this guy rambles a bit, but does the best job of explaining the system I’ve seen. Admittedly I think I had to watch it 4 times before it started to make sense. By the way, there is a part 2 to it.


I have watched it also a couple of times, and it still does seem that I should have 12 v on the feed side of 2 wire connector at the oil pressure switch. He didn’t clearly say whether the ign is on or not, but I suspect on, and I don’t have power there.
I guess I should find the ECM and see if the blu/bl wire is there and see if I have continuity from beginning to end.
i Don’t have the expensive testing equipment that the guy in the video had, plus to be honest, I am not as knowledgeable as he is either. It seems like he has a degree in electronics of some sort?
but I also am going to change oil/ with correct oil and hoping. That won’t do a thing to bring 12v in though will it 🙂
 

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I work at an auto shop, just got here for my day. I pulled up the wiring diagram which is straight from Honda in our software.

Looming from the front of the vehicle towards the firewall:

On the left of the pack in the back corner is the solenoid which has ground and power. To the right of it is the oil pressure switch, also 2 wires.

If you use a DMM and switch to continuity test, start the engine the oil pressure will close the circuit completing the ground through the switch. Once they ground is completed that supplies the ground for the solenoid.

Oil pressure switch cannot have a power and a ground because the computer has to know the circuit is closed, so it has to complete a circuit just like an on off switch. It could actually function off a one wire design like the oil switch just above the filter does, using the engine block as the ground instead of a second wire.

Did you check the solenoid valve that mounted in the middle of the timing cover just above the drive/serpentine belt?

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He didn’t clearly say whether the ign is on or not, but I suspect on, and I don’t have power there.
....
i Don’t have the expensive testing equipment that the guy in the video had, plus to be honest, I am not as knowledgeable as he is either. It seems like he has a degree in electronics of some sort?
yes, I’m pretty sure his pressure switch measurements are with KeyOn EngineOff (KOEO), using backprobe technique until he disconnects the connector. I think he started there because his scan tool showed that his switch was not activating correctly, therefore he wanted to check wiring before condemning the switch.

backing up, he starts with a scan tool that has vtec solenoid and pressure switch PIDs To show that his pressure switch does not turn off when the solenoid goes on. His Autel MaxiSys (available on amazon, is a pretty popular non Honda aftermarket scan tool), has the bidirectional control, but it seems that you may not need bidirectional control if you have access to the PIDs, you could get the same data just by driving it.

im not sure who the guy in the video is, I just found him randomly. It seems that he is well versed in auto repair and probably does it a lot.

I work at an auto shop, just got here for my day. I pulled up the wiring diagram which is straight from Honda in our software.

Looming from the front of the vehicle towards the firewall:

On the left of the pack in the back corner is the solenoid which has ground and power. To the right of it is the oil pressure switch, also 2 wires.

If you use a DMM and switch to continuity test, start the engine the oil pressure will close the circuit completing the ground through the switch. Once they ground is completed that supplies the ground for the solenoid.

Oil pressure switch cannot have a power and a ground because the computer has to know the circuit is closed, so it has to complete a circuit just like an on off switch. It could actually function off a one wire design like the oil switch just above the filter does, using the engine block as the ground instead of a second wire.

Did you check the solenoid valve that mounted in the middle of the timing cover just above the drive/serpentine belt?
sweet info.


for what it’s worth, I’m curious if Until60 put in an aftermarket or an OE Honda solenoid? the reason I first posted in this thread was to give my example where I really regretted putting in an aftermarket solenoid, leading to months of wasted time chasing out what the heck is going on. It was something like $50aftermarket, $250 Honda. If I just spent more initially, and went with OE Honda equipment on this one, I would have saved much more In the long run.
 

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Discussion Starter · #17 ·
I work at an auto shop, just got here for my day. I pulled up the wiring diagram which is straight from Honda in our software.

Looming from the front of the vehicle towards the firewall:

On the left of the pack in the back corner is the solenoid which has ground and power. To the right of it is the oil pressure switch, also 2 wires.

If you use a DMM and switch to continuity test, start the engine the oil pressure will close the circuit completing the ground through the switch. Once they ground is completed that supplies the ground for the solenoid.

Oil pressure switch cannot have a power and a ground because the computer has to know the circuit is closed, so it has to complete a circuit just like an on off switch. It could actually function off a one wire design like the oil switch just above the filter does, using the engine block as the ground instead of a second wire.

Did you check the solenoid valve that mounted in the middle of the timing cover just above the drive/serpentine belt?

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Hi, code is P2646 and that didn’t lead me to the solenoid valve you mentioned. I will look for it.
i was under the assumption that the Rocker arm oil pressure switch was turned on and off by the computer so that was how it different than the oil pressure switch by the filter, which has power to it all the time when ign when power is on. But I guess your right, why couldn’t it be the same and the power run thru the computer. Must be a reason though?
yes, I’m pretty sure his pressure switch measurements are with KeyOn EngineOff (KOEO), using backprobe technique until he disconnects the connector. I think he started there because his scan tool showed that his switch was not activating correctly, therefore he wanted to check wiring before condemning the switch.

backing up, he starts with a scan tool that has vtec solenoid and pressure switch PIDs To show that his pressure switch does not turn off when the solenoid goes on. His Autel MaxiSys (available on amazon, is a pretty popular non Honda aftermarket scan tool), has the bidirectional control, but it seems that you may not need bidirectional control if you have access to the PIDs, you could get the same data just by driving it.

im not sure who the guy in the video is, I just found him randomly. It seems that he is well versed in auto repair and probably does it a lot.



sweet info.


for what it’s worth, I’m curious if Until60 put in an aftermarket or an OE Honda solenoid? the reason I first posted in this thread was to give my example where I really regretted putting in an aftermarket solenoid, leading to months of wasted time chasing out what the heck is going on. It was something like $50aftermarket, $250 Honda. If I just spent more initially, and went with OE Honda equipment on this one, I would have saved much more In the long run.
I bought solenoid at local parts house, so of course I don’t know if its faulty out of the box, that why I am trying to determine if wiring is good?
so back to the oil pressure switch wiring. I seem to be getting different opinions. What’s the consensus?
so I pulled off the 2 wire connector to the oil pressure switch. should I have 12v on the bl/bl wire of the connector, ign on/ engine off ?
I really appreciate you guys taking time to read this stuff. It’s always a great help to hear opinions! and it’s not bullshit. I get a lot of satisfaction being able to fix stuff and learn along the way.
 

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ok, I’m learning more too. So i own a 03 crv and a 03 element. I thought these two cars were virtually identical. I just got to look at the service manuals. What’s weird is that the 03 crv does not have a p2646 code, it rather a p1259 vtec malfunction code; whereas the 03 element does have a p2646 Code. And the crv manual I looked at lists 02-03 models. So it’s possible your 04 model is different. Let me see if I can figure out how to upload some pictures on the next few posts.
 
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