Fog lights on with high beams mod

[HenryJ]

I know you probably thought the answer would be here...sorry.

What would it take to do this? Snip a wire at the BCM? Snip a wire at the relay?

There has to be a wire that signals the BCM to shut them off when you switch to highbeam.

I wouldn't mind having them available as filler lighting down low when I have my quadbeams running.

Anybody want to look into this , or have an answer?

Maybe I'll look into it further after I finish the current project.

[AZS10Crew]

You know there's a major issue when the king of S-10 Crewcab wiring asks a wiring question.

[2bunik]

I don't know about your fog lights. but mine seem pretty useless.. I try to use them everyonce in a while but I think a candle provides better light..

[Mat73GNZ]

I don't know about your fog lights. but mine seem pretty useless.. I try to use them everyonce in a while but I think a candle provides better light..

I feel the same way. I think I'll try those 50 watt bulbs and see if their usefullness (the fog lights) will improve at all.

!M!

[F9K9]

There has to be a simple mod to make it work. I would think it has to be similar to performing the quad mod but, will leave it to the wise ones to figure out.

I wanted to do the mod on a '91 Laser but the dealership's only mechanic (very small dealership....lol) couldn't figure it out.

[top_sgt]

is there a way to reroute the wiring to tie the fog lights into the parking lights??? have done this with aftermarkets.....haven't seen a wiring diagram for the factory lights.

[top_sgt]

and i was thinking(i know......it can be dangerous!!) if you do the quad mod.....shouldn't the fogs stay on with the low beams????

[KCustom]

I believe that the fogs are a negitive trigger from the switch....if that is the case then the high beam switch drops ground to the fogs. I believe you would just need to add a relay to the fog ground trigger off of the high beam neg and this would leave them on for high an low beam opperation....I will try to put a meter on it and see

[barch97]

Y'all should check with your local law enforcement authority before doing this. In NJ anyway, vehicles are prohibited from having more than four forward facing white lights on simultaneously. Although, I don't know anyone that's ever been ticketed for such an offense.

39:3-56. Number of driving lamps required or permitted
At the times when lighted lamps are required, at least 2 lighted driving lamps shall be displayed, an equal number on each side of the front of every motor vehicle other than a motor cycle and other than a motor-drawn vehicle except when such vehicle is parked subject to the provisions governing lights on parked vehicles or is flashing vehicular traffic hazard warning signals as provided for in sections 39:3-54 and 39:3-64. Whenever a motor vehicle equipped with headlamps as in this article required is also equipped with auxiliary lamps or a spot lamp or any other lamp on the front thereof projecting a beam of an intensity greater than 300 candlepower, not more than a total of 4 of any such lamps on the front of a vehicle shall be lighted at any one time when upon a highway.

[HenryJ]

and i was thinking(i know......it can be dangerous!!) if you do the quad mod.....shouldn't the fogs stay on with the low beams????

That sounds logical, but doesn't work.

You are not turning the lowbeams on , but rather keeping them lit when the highbeams are on. At least the BCM perceives them to be off

[adrenalnjunky]

I figured this out for my Z24 - if it helps there was a bank of 3 relays in the lower radiator support and the one furtherst to the driverside of the vehicle had a pink wire. that was the trigger - I snipped it, and the fogs worked independently of the headlights (other than the fogs only powered on when the parkinglights were on at a minimum.)

I'm betting it's something very similar for the s-10 platform. Unfortunately, I don't have a foglight equipped truck, so I can't test on mine.

[Walt]

Sorry to drag up a dead thread, but has anyone ever made any progress with this?

[F9K9]

Not that I know of but since it is BTT and the driver's side radiator support and relay was brought up............What is that thing that looks like a plugged vacuum line and plugged harness doing there under where the stock air box would be?

[crew cab sonoma]

i dont know for certain, but supect that the fog lamp relay coil grounds through the high beam filaments. when the high beams are turned on, the relay loses it ground path.

a quick check for this could be to unplug the high beam bulbs to see if the fog lights will turn on at all.

if this is the case, it would seem that all you would have to do is cut the ground wire to the relay, and connect it to a chassis ground.

[crew cab sonoma]

i doubt the BCM controls this fuction, when a simple grounding trick will do the job.

i`ve never noticed, do the fog lights cut off when using the "flash to pass" feature as well?

[crew cab sonoma]

checked over the weekend. the fog lights do indeed cut off using the flash to pass.

i will check into this more later this week.

[crew cab sonoma]

ok. i did a little more checking into this. it looks like the fog light relay coil might be grounded by the BCM.
leave it to GM to turn something simple into something complex....

the fog light switch is a momentary type, grounding an orange wire only while being pressed.
but it still functions even when the ign. is off.

i guess the next step is to disconnect the BCM, and see if they still function.

[2kwik4u]

I've been adding foglights to an otherwise non-equiped truck (on my Xtreme)......YOu need to gound a white wire from the BCM when you want the fog lights on. It's a fairly simple relay wiring job. I've got it setup on the Xtreme that when the parking lights are on, the foglights are on.

I'll try to get some time this weekend to look at the truck, and get pin numbers and post up which wire to ground to get the foglights on.

[crew cab sonoma]

yeah, i suppose the addition of DRL`s necessitates the need for BCM control of the fog lamp circuit. didnt think about that before...

does grounding this white wire enable the fog lights with the high beams?

BTW, where is the DRL module located at on our trucks?

[2kwik4u]

The DRL are also controlled by the BCM I believe.

If you want to disable teh DRL's you can usually just break two prongs off a relay in the relay box, and the DRL's go away......at my Xtreme worked that way.

Grounding the white wire will enable the fog lights anytime the parking lights are on.

[crew cab sonoma]

i figured the DRL`s and AHL`s were controlled by the BCM. and i have already disabled both. bent up one pin on the DRL relay, and the resistor mod for the AHL`s...

what does this white wire normally do, or go to?
does it have to be cut, and grounded on the BCM side?

and i think the BCM is under the center on the dash, correct?

i just didnt know where the DRL module was located at...

[2kwik4u]

Not sure that there is a DRL module......although I'm not 100% sure of that.

The white wire runs from the fuse block to the BCM....You can cut it, and ground it to enable the foglights, or you can splice into it and ground it.....doesn't matter I don't think.

[crew cab sonoma]

did the BCM absorb the "dimming" functions of the DRL module? and how is the dimming effect done? resistance, or voltage regulation?

exactly what all is controlled by the BCM?
AHL, DRL, interior lighting? instrment cluser, i think. or does the cluster just process its own serial data? how about the heat mixing door on the climate control?

anything else?
thanks.

[2kwik4u]

BCM controls LOTS of stuff.....I'm thinking the DRL module is included in that....No idea how it's done though.

I know the gauge cluster processes it's own serial data. As does the stock radio (thats how speed sensitive sound works). I think there are some other "consumers" of the serial data from the PCM as well, but I'm not 100% sure.

[crew cab sonoma]

thanks for the info.

so, is this white wire the one that grounds the fog light relay? sounds like it is.

but if you ground this wire, the fog light will be on anytime the parking lights are on, right???
meaning you cant turn them off, separate from the parking lights?

[2kwik4u]

thanks for the info.

so, is this white wire the one that grounds the fog light relay? sounds like it is.

but if you ground this wire, the fog light will be on anytime the parking lights are on, right???
meaning you cant turn them off, separate from the parking lights?

100% correct......I would put it on a switch, or relay that either you control, or something else controls.....

[crew cab sonoma]

ok. next question. instead of grounding the white wire, with the DRL function disabled, does the BCM no longer need a signal feed from the high beam circuit, or does the BCM actually control the high beam circuit?

it would seem that if the BCM doesnt control the high beams, and only gets a signal from them, that this wire could be cut, and the fog lights would remain on with high beams, and you could still turn them on/off when the parking lights are on?

[HenryJ]

The BCM contains the bipolar latching relay for the fog lights.
The high beams each have a positive and negative feed when functioning normally. When they are in DRL mode they run in series. One light is the positive and the other is the negative, for a reduced intensity DRL. Throw the AHL into the mix and I would say that there may quite a few of their functions that are controlled by the BCM.

I don't want to confuse your train of thought here. Just adding a little , very little information, that may or may not even be relevant.

[crew cab sonoma]

no, very good info HJ. thanks. i didnt realize thats how the DRL`s functioned.

so, is there still a separate DRL module?

[2kwik4u]

I forgot all about snagging these schematics awhile back from GM's site (had a buddy with higher level access that let me in ).....It might help alot with the problems at hand

http://s91879901.onlinehome.us/gallery/schematics

[crew cab sonoma]

thanks! after some study, it looks like schematics 3 and 5 show the fog lamp circuits to be as we discussed, except the "white" wire we talked about, is dk. green/white in the shematic (ckt. #1317) and shematic 6 shows a "high beam input" to the BCM. purple wire, circuit #524, pin B5, on conn. A11 on the BCM?

it doesnt seem to indicate that its switched by the BCM, but rather just a sensory input???

could disconnecting this wire from the BCM be the key to keeping the fog lights on with the high beams???

not sure what other functions, other than MAYBE the DRL`s, disconnecting this wire could impact?

[2kwik4u]

I hadn't thought of it that way, but I suppose it could be.....If I had better access to the BCM I'd try since pulling a pin from the connector is not all that hard.

[crew cab sonoma]

i think "A11" is a circuit #, not a connector#. although it shows 2 of them.
the legend shows C1, C2, and C3, as connector #`s... not sure if thats all of them to the BCM...

so im not sure which connector pin B5 is on...
perhaps C2???

also, to anybody looking at these schematics, bear in mind they are for 2000 models, i think. so there may be differences for other model years, or crew cabs....

[crew cab sonoma]

ok. i tried this over the weekend.... does not work.
disconnecting the purple wire (B5) on the lt. blue connector (C2), would not allow the fog lights to turn on with the headlights at all, low or high beam...
and the high beam indicator stayed on with both low and high beams.

perhaps the only solution to this is to install a conventional on/off switch in place of the momentary type fog light switch, and remove the the BCM from the process by disconnecting the green/white wire (pin A7,lt. blue connector), and the orange wire (pin B5, purple connector), at the BCM, and spicing them together.

then the fog lights would work as desired.

[rockinjranch]

Has anyone made any progress on this? I sure hope so as I would like mine to stay on with the high beams.

[HenryJ]

It has been a very long time. I have done this mod on my Avalanche: FTDRL and All-On-High or download the file here: FTDRL Install for a Chevy Avalanche.PDF
Could you use a diode to make this work on the crew cab?

[rockinjranch]

this as is will not work for the S10, different set up in the fuse center, but a very interesting way to achieve my goal. I will study it further ,perhaps it can be adapted to the s 10's.

[HenryJ]

All you need is to add a diode from the high beams to the fogs relay. The fogs already stay active with the lowbeams.
Keep in mind that if you are running the ALL on High mod and add the fogs , that is six headlamps illuminated and may not be legal in some states. Oregon permits only four lamps illuminated for highway use.

[rockinjranch]

you may be correct, however remember our (my) trucks under hood fuse center doesn't have separate relays for low and high beam but instead has one relay for "HDLP PWR" and then two fuses "LT HDLP" & "RTHDLP". determining where to come from with the diode to the fog relay is in question.

[HenryJ]

Could you run a wire from the highbeam headlamp wire, use a diode in that wire and connect it to the foglamp relay activation? Keep in mind that the Highbeam DRL operation has them running in a series for DRL operation and parallel during normal operation. This presents a new level of complication in that you don't want the fogs coming on with the DRL. In that case disabling the DRL may be a necessity to successfully make this modification? I do not recall which side headlamp had the rotating polarity for DRL operation. I think it was the left side. If that is the case it may be possible to tap the right side and make this work with the DRL.
Lots to wrap one's head around. Harder yet without one in you driveway here

[rockinjranch]

DRL's are disabled so they are a non issue,your idea of taping from the highbeam lamp sounds feasible ,but if the BCM drops ground to the fog relay on highbeam then that signal wire will need to be cut to keep the fogs on. ill study on this over the weekend!