Enable cargo lights while driving...

[Grimloktt]

I'm going to preface this dicussion by addressing the legal aspect. I read another thread (and have had my own) where admin or members were VERY legal sided. (Not to say that that's wrong...anyway, that's a discussion for another time, another place.) All that that to say, in order to permit this thread, I'm clarifying that I have a cap/topper on my bed. I don't know the lines of the law; however, if SUV lights can turn on while driving (and they can), I'd reason that a capped truck would also be legally allowed to do so.

Now, on to the topic at hand:

I wanted to enable my cargo lights while driving. I've purchased the electrical manual to check out the schematics. Within the light circuit (a lot of circuits as a matter of fact) is what's called a MICU or multiplex integrated control system. This is a "black box" meaning the manual doesn't tell you a lot about the guts of this system. So, looking at the schematic for the cargo lights, there is a relay for the lights (power coming directly from the battery and through the realy to the lights when the relay is powered). To power the relay, power comes through the relay (same pin that supplies it power) and into the MICU. From the MICU goes to the switches to turn on the lights (dash cargo light switch, tailgate switch and trunk switch--all different wires from the MICU).

OK. So, I thought I could bypass the MICU by connecting a wire from the outlet of the relay control (between the outlet control and the MICU) and into the dash switch (all switches lead to ground). I didn't cut the existing circuit; I just added the loop. Here's what happened.
- If I turn on the cargo lights while in park, I can't turn them back off with the switch. I have to shift into gear or open the tailgate/trunk.
- I can turn on the cargo lights while driving; however, you have to hold in the button as it's not a toggle type switch.
- The lights come on for a split second when I open the tailgate or trunk, but don't stay on.
- If I turn on the lights from the dash, I think the lights stay on while I open the gate--either that or the gate was open and I pushed the button and they stayed on.

Anyways, I'd like it to operate like factory; however, I don't think it's possible with the MICU...for some reason. Can anyone think how to do it?

Here's a pic: From the relay area yellow wire w/ blue stripe (installation of hitch provides intructions on how to get to this) to the green wire on the cargo switch.

[Grimloktt]

I think what I might try to do is:

1) Cut the yellow wire w/ blue stripe that goes into the MICU.
2) Have that yellow wire w/ blue strip (ground of relay controller) connect to the tailgate/trunk grounding switches, in addition to the already connected cargo switch. (They are the blu/orn and blu/yel wires that run to the under-dash fuse/relay box.)
3) I may install an on/off toggle switch for the cargo switch.

Thoughts?

I don't want to disconnect the wires from the MICU to the tailgate/trunk switch b/c I think they also send input when the doors are open for the door lock/unlock and alarm...

[shovelhd]

Whatever you do, make sure the power to the lamps goes through a relay with battery source power. I would not trust the dash switch to switch anything beyond 5A.

[Grimloktt]

Before power comes into the circuit (relay), it runs through the 7.5amp fuse.

[ZooDirt]

I think this is good information. All I did was flame everyone...so you've already done way more work on this than I have... I'm scared of cutting any wires because I don't know exactly what I'm doing. Anyway, I still have some input.

It seems like the main issue here is that the MICU (or maybe something else) "knows" that the vehicle is in park. Wouldn't it be simpler to disable/tinker with that functionality? If the cargo lights "thought" the vehicle was in park wouldn't the cargo switch operate normally?

If the MICU (or this specific MICU) exists only for the cargo light switch, then one may only have to track down one wire going to the gear shift (or transmission or other).

You know WAY more about it than I do, Grimloktt, but those are my thoughts...

[ChrisM]

If you don't disconnect the wire to the multiplex unit, you risk smoking it and it ain't cheap. (Honda's list price is about $700 but Majestic sells it for about $500.)

You are essentially backfeeding it current from the wrong side of the circuit. That is why you are having the problems that you are having.

The safe way to do this is to wire a new circuit and install a seperate set of lights. If you cut the multiplex wire, you risk voiding your warranty. Modifications don't void your warranty but Honda will find a reason not to warranty the electrical circuits if they see that you have modified them.

PS. Are the lights being on inside the cap legal? I don't know but I would guess that the answer is no since it would still be a rearward illuminated white light brighter than 10 candela or whatever it was.

[ZooDirt]

Please, let's skip all legal claims or warnings unless you've included a link to back it up...

[Grimloktt]

Originally Posted by ZooDirt

I think this is good information. All I did was flame everyone...so you've already done way more work on this than I have... I'm scared of cutting any wires because I don't know exactly what I'm doing. Anyway, I still have some input.

It seems like the main issue here is that the MICU (or maybe something else) "knows" that the vehicle is in park. Wouldn't it be simpler to disable/tinker with that functionality? If the cargo lights "thought" the vehicle was in park wouldn't the cargo switch operate normally?

If the MICU (or this specific MICU) exists only for the cargo light switch, then one may only have to track down one wire going to the gear shift (or transmission or other).

You know WAY more about it than I do, Grimloktt, but those are my thoughts...

That's a good point; I'll explore that option. Maybe this would be the easiest course of action...

Originally Posted by ChrisM

You are essentially backfeeding it current from the wrong side of the circuit. That is why you are having the problems that you are having....

Another good point. I'll have to think about that.

[smroycro]

Originally Posted by ZooDirt

Please, let's skip all legal claims or warnings unless you've included a link to back it up...

objects in the mirror are closer than they appear....

http://www.flickr.com/photos/60707191@N00/1547055192/

[ChrisM]

Originally Posted by ZooDirt

Please, let's skip all legal claims or warnings unless you've included a link to back it up...

Since you mentioned it....

Section 24003 of the California vehicle code states:

Article 15. Light Restrictions and Mounting
Color of Lamps and Reflectors
25950. This section applies to the color of lamps and to
any reflector exhibiting or reflecting perceptible light of 0.05
candela or more per foot-candle of incident illumination.

Unless provided otherwise, the color of lamps and reflectors
upon a vehicle shall be as follows:
(a) The emitted light from all lamps and the reflected light
from all reflectors, visible from in front of a vehicle, shall be
white or yellow, except as follows:
(1) Rear side marker lamps required by Section 25100
may show red to the front.
(2) The color of foglamps described in Section 24403 may
be in the color spectrum from white to yellow.
(3) An illuminating device, as permitted under Section
24255, shall emit radiation predominantly in the infrared
region of the electromagnetic spectrum. Any incidental
visible light projecting to the front of the vehicle shall be
predominantly yellow to white. Any incidental visible light
projecting to the rear of the vehicle shall be predominantly
red. Any incidental visible light from an illuminating device,
as permitted under Section 24255, shall not resemble any
other required or permitted lighting device or official traffic
control device.
(b) The emitted light from all lamps and the reflected light
from all reflectors, visible from the rear of a vehicle, shall be
red except as follows:
(1) Stoplamps on vehicles manufactured before January
1, 1979, may show yellow to the rear.
(2) Turn signal lamps may show yellow to the rear.
(3) Front side marker lamps required by Section 25100
may show yellow to the rear.
(4) Backup lamps shall show white to the rear.
(5) The rearward facing portion of a front-mounted
double-faced turn signal lamp may show amber to the rear
while the headlamps or parking lamps are lighted, if the
intensity of the light emitted is not greater than the parking
lamps and the turn signal function is not impaired.
(6) A reflector meeting the requirements of, and installed
in accordance with, Section 24611 shall be red or white, or
both.
(c) All lamps and reflectors visible from the front, sides, or
rear of a vehicle, except headlamps, may have any unlighted
color, provided the emitted light from all lamps or reflected
light from all reflectors complies with the required color.
Except for backup lamps, the entire effective projected
luminous area of lamps visible from the rear or mounted on
the sides near the rear of a vehicle shall be covered by an
inner lens of the required color when the unlighted color
differs from the required emitted light color. Taillamps,
stoplamps, and turn signal lamps that are visible to the rear
may be white when unlighted on vehicles manufactured
before January 1, 1974.
Amended Sec. 4, Ch. 198, Stats

This information may also be found under the Code of Federal Regulations, Title 49, Volume 5, Parts 400 - 999 which is also known as the Federal Motor Safety Code