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Discussion Starter #1
2007 CRV EX manual diesel. 152k on the clock.

Few weird electrical faults really need fixing, may all be linked to a single issue. Any help really appreciated as me and my local garage are lost and don't know where to start.

1. When I turn the lights on, the rear brake lights come on and stay on constantly regardless of pressing the brake pedal. This does not change when I press the pedal.the only way you can turn the brake lights off is to turn the lights off.

2. When I press the brake pedal, the sat nav screen dims. (Goes into night mode, if I'm on the map it goes black)

3. When the lights are on. I can't use the cruise control. (Works fine when the lights are off)

So when I'm driving in the night and have to turn the lights on, I can't use the cruise control and the brakes lights are on constantly. 馃槖

The local garage plugged it in to get diagnostics and it came up with faulty brake switch, I changed that and it didn't make a difference. Same code still comes up.

as for the brake lights I'm going to check brake fluid level tomorrow. The rest of the issues I do not know where to even start. Thanks in advance for any info given.
 

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Welcome to the forum! Was anything done before this happened? It looks like you have a bad, rear brake light bulb or a parking light bulbs. Remove the rear brake bulbs 1 at a time then depress or turn on the lights on see if the brake lights come on. Let me know.
 

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I don't understand how a faulty brake switch can have any relationship with the lighting circuit. It's also a simple SPST NO switch that should be easy enough to test on it's own in the car by pulling the plug. Sounds like a short somewhere, which would explain why the brake switch continues to fault despite being replaced because the circuit it's attached to is bad (uou will probably find the original switch is good).

Shorts can be a PITA to find. You don't have any aftermarket accessories hooked up (fog lights etc) that are hooked into the wiring that might be wrong (or previous installation / modification of wiring) ?

Might be helpful to get a copy of the service manual here as it has all the wiring information including harness locations, pinouts and wire colors (the ch12 file / book chapter 22-148). It really sounds like the brake and light circuits are shorted together at some point. I'd start by pulling fuses and disconnecting harnesses to try and isolate the two circuits.
 

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Discussion Starter #4
Thanks Otto888man!

I've done what you said, took each bulb out individually and checked if any change while out. both brake and sidelight bulbs, no change.
 

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Discussion Starter #6
Hi Tom, all very helpful, I've been thinking a short somewhere it's just finding it. You think both lights and brake lights circuits are shorted together then ok. Do you think this could still effect the sat av screen changing and stop cruise working or is this a separate issue? Cheers
 

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How about the front parking lights have you taken them out too? Yes, they will also be affected the cruise control, the radio / Navigation as they are also powered & has the same circuit as the park lights. How about the 3rd brake lights have you tried to pull the socket or the bulbs out. Tom has nailed the theory & cause of your problem. Its just a matter of finding it. Let us know.
 

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Almost sounds like you lost a ground (-) somewhere (probably in the headlight circuit) and it is now going through the brake lights , etc.
Check your main grounding straps. There is one from the battery neg to the frame and one from the frame (near the top of the radiator) to the engine.
Studying the electrical circuits for the brake lights and following its circuit to see where its grounds all connect may give you the clue you need.
A blown fuse can cause similar symptoms, but it is usually a bad ground.
Could be a shorted out headlight relay. Just guessing.

Buffalo4
PS: Are you sure it is the brake lights (brighter) that are on and not just the tail light portion of it?
Does it make a difference if the headlights are on high beam or low beam or if just the parking lights are on?
 

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Definitely related. Cruise Control fails because it thinks the brakes are on. Nav dims because it thinks the lights are on. The short between the brakes and lights makes them one circuit, so anything related to one of them now affects the other.

Double check the brake bulbs, that's the most common place the two are in close proximity to each other. In fact, I'd take all the bulbs out of the back (just remember which went where) and test.

Flexible harnesses are another failure point due to the abuse they take. Remove the 3rd brake trim and the rubber wiring tube at the top of the hatch for damage (I think an interior light wire runs next to the brake for the hatch lock switch through that tube).

Next up would be to pull the brake light fuse and see if there is any change. Just noticed you said you have a diesel - in the gas version the brakes are fuse 12 located in the under hood box. Then the running lights - under dash fuse 15 in the gas version. These are probably the same in the diesel, but double check. See if anything changes.

edit - going on Buffalo4's thoughts, pull the headlight fuses as well and check again.
 

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Discussion Starter #11
Great thanks a lot guys. Gives me plenty to check over (hopefully tomorrow) I'll action all suggestions and let you know how I get on! 馃榾
 

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I note there are additional fuses for the parking lights (Dash 19), Low Beam (Dash 21) and High Beam (Dash 18) that are controlled by the MICU computer. These are additional power sources that I would try and isolate to see if they effect the problem.

Also, I just re-read your description and note that the brake lights come on when you turn on the lights, but you do not mention if the lights come on by hitting the brakes (though the NAV unit thinks they are because it dims)... Do the lights come on by hitting the brakes? Does it matter parking lights vs headlights? If the lights do not come on that is a clue.
 

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A couple of questions.

With the headlights switched off and brake pedal pushed down, the sat nav screen goes dim?
With the headlights switched off and brake pedal pushed down, no brake lights go on inc the high brake light? Same with ignition off and on?
Does your horn work with the headlights on? With them off? If not, check fuse 12 (15a) in the under the hood fuse/relay box.

Check ALL fuses is a good starting point, and it does take some time and contortions. :eek:
Buffalo4
PS: If you search enough on the Internet, you will find a site that will give you a free Service Manual for the 2007 CRV (at least a gas model one). That includes some good electrical diagrams and good troubleshooting advice.
 

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i Would suggest to also take a closer look on the terminals where the brake & park light goes into. they might have touched. good luck hunting!
 

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Discussion Starter #15
Buffalo4 answers below 馃榾

A couple of questions.

With the headlights switched off and brake pedal pushed down, the sat nav screen goes dim?

Yes

With the headlights switched off and brake pedal pushed down, no brake lights go on inc the high brake light? Same with ignition off and on?

Brake lights still come on fine with lights off. Same with ignition on and off.

Does your horn work with the headlights on? With them off? If not, check fuse 12 (15a) in the under the hood fuse/relay box.

Yes, works fine with lights on and off

Check ALL fuses is a good starting point, and it does take some time and contortions. :eek:
Buffalo4
PS: If you search enough on the Internet, you will find a site that will give you a free Service Manual for the 2007 CRV (at least a gas model one). That includes some good electrical diagrams and good troubleshooting advice.
 

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With the headlights switched off and brake pedal pushed down, no brake lights go on inc the high brake light? Same with ignition off and on?

Brake lights still come on fine with lights off. Same with ignition on and off.
Just to clarify... pushing brake pedal with lights off, brake lights come on BUT tail lights do NOT come on? If that is the case it must be a clue because the two circuits are "shorted" in every other way but this. So that would indicate a potential ground fault or perhaps something with the MICU computer connections.
 

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Discussion Starter #17
Just to clarify... pushing brake pedal with lights off, brake lights come on BUT tail lights do NOT come on? If that is the case it must be a clue because the two circuits are "shorted" in every other way but this. So that would indicate a potential ground fault or perhaps something with the MICU computer connections.
No, with the lights off, I press the brake and tail-lights and brake lights come on, 5 lights in total, unusually the left front side-light also comes on 馃槙
 

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OK, at least that makes sense (though obviously wrong). And your right front side-light is probably burnt out because it should be lit too ;-)

The brake circuit and the light circuit are shorted together somewhere. The brake bulbs are the common culprit, but you said you took them completely out of the car... Next step is trying to isolate different branches one at a time... I would try unplugging both taillight assemblies at the wiring harness plug located behind the lenses, and also the main harness plugs to the hatch located behind the left D pillar trim, because I think those areas have the highest probability and hopefully you can pinpoint the branch with the short (the brake bulb sockets have the two circuits within a fraction of an inch of each other). If that fails to locate the short then you move to the under dash area and continue tracing the brake light circuit (which are the lt green wires going from the pedal switch to the fuse box). I would use an awl or icepick to pull #34 lt green wires out of Plug "E" on the under dash fuse box which feeds the brake power to the rear harnesses you pulled earlier. Last of all is lt green wire #30 in Plug "F" under dash which provides the brake signal to the computer. That pretty much covers the entire brake circuit and one of those should point you to the actual short. The Service Manual link I provided earlier identifies all the locations for these plugs.

edit - don't know why I didn't think of it earlier, but is there or has there ever been wiring for a trailer installed? If so, there's another likely trouble spot.

edit 2 - just to clarify the tests harness test above, I would unplug one at a time and check if things have changed. If not, reconnect the plug and move on to the next one. Or you could unplug all of them and press the brake pedal to see if the front side marker lights come on.
 

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Hopefully your issue ends up being a simple wiring problem or bad bulb socket, but I discovered this thread here with a somewhat similar issue where the short ended up inside the fuse box itself. Unfortunately, I could see how this would cause your problem as well. But let's eliminate the wiring harnesses first.

A few weeks ago my power door locks, and warning noises all stopped working on my CRV. My Brake light is also having a problem where it will no longer turn off. Do any of you know what would cause this problem, or have any of you had this problem yourself? My mechanic says that it is caused by a malfunctioning Multiplex Control Unit... which costs over $400 at Honda.
The location of the underdash fuse box on the '07 and up models allows any fluid spilled on top of the dash to run along the defroster vent channel and drip directly down onto the fuse box.
The way to test for this would be to pull wire #E34 out of the fuse box plug, then test for 12V on the pin the wire was connected to with the plug still connected to the fuse box and the light switch turned on. This would indicate that the brakes are being fed 12V from a short in the fuse box or the Multiplex Control Unit attached to it.
 

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With the headlights off, the brake lights (all 3) plus the taillights (2) plus the front left parking light come on when you press on the brake pedal (rt pk light prbly burnt out, like TomKatt suggests) but the fuse doesn't blow then, is that correct?
I wonder if it couldn't be as simple as faulty turn signal relay? Wild guessing.
Buffalo4
 
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