Headlight retract/shutoff issue re-post

[DS_Porter 89 Burgandy]

I am re-posting my fix for the headlight shutoff issue posted Jan 3 2018. Originally the grounding was run through the low beam filament. If the headlights are changed to LED's the resistance is too high and they will not retract. Here is my previous post explaining the fix.....

 

See page 8A-102-0 in the '89 FSM

On the Headlight Control Module connector C1 terminal C I cut the wire and capped the wire leading away from the HCM connector. I connected a 16ga wire to the severed wire C coming out of the plug and I ran that wire to a good ground.

 

The LED bulbs I chose are much brighter than any incandescent and well worth this modification. Any type bulb can be installed and they will retract just fine.

[DAVES89]

Does that replace having to buy the relay harness and can you post a picture?

Edited March 20, 2020 by DAVES89 (see edit history)

[Ronnie]

38 minutes ago, DAVES89 said:

Does that replace having to buy the relay harness and can you post a picture?

 

I posted this solution here along with the wiring diagram (thanks to DS_Porter) and it was quickly dismissed with everyone jumping on the aftermarket harness bandwagon. This modification to the headlight door module wiring should work to make the doors close when using low resistance lights like the LEDS. However, it won't take the load off the headlight switch if that is the goal.

Edited March 20, 2020 by Ronnie (see edit history)

[DAVES89]

Thanks Ronnie. I have an extra harness now that I no longer have the '89 Black. Will install it on the '88 Black with the Truck lites. and yes I do want to take the load off the headlight switch.

[KDirk]

May I point out that the LED headlights significantly reduce the total load on the switch. Stock Guide brand halogen low beams were 35w each, most modern halogen lowbeams are 50w each, with high beams being higher still obviously. That said, going to LED headlights takes a lot of the heavy load from the headlight switch to begin with, leaving only the taillamps, license plate, and front running lights as conventional lighting load.

 

I've used LED 194's for the license lamps, and have fitted amber LED 194's for front running lights on one of mine so far, and reduced the load that much more. Tail lamps and running/turn lamps up front generally need to stay incandescent due to the blinker load sensing problem and complexities of the dual voltage design of the running/turn signal halogen lamps up front. There are workarounds for using LEDs in the tail lamp, however 

 

I still like the harness idea better as a more comprehensive solution, but the soltuion offered by DS-Porter is a good one as it is. If nothing else it lets one use LED headlamps immediately without the added work and cost of the harness retrofit needing to be done right away, and can always be fitted later as time and funds permit. Getting the immediate improvement in light output is a big plus. 

[DS_Porter 89 Burgandy]

  When I converted to LED headlights I wanted to understand and solve the problem of the lights not retracting because I was looking to benefit from the reduced stress on the

headlight switch. It seemed like adding a relay harness was redundant although it is still the best fix to reduce stress on the switch regardless of which headlight type is selected.

  When I selected the LED headlights to install it was more than two years ago and direct replacement rectangular  lamps were not readily available. I settled for a pair that is not yet DOT certified. They have three rows of four large bright LED's. Six turned on for low beam and all twelve for high beam. Way brighter than the best stock halogen or regular incandescent. The problem however was the low beam pattern was the same as the high. I was getting a lot of drivers flashing me due to the low beam wide pattern.

  So I ended up partially blocking the six low beam LED's with a carefully cut piece of electrical tape. Most all the light above horizontal is blocked. No more drivers flashing me and the pattern is still plenty bright. I think my high beams are the brightest on the road.

  I leave my fog light switch on at all times for general safety and also because it looks sharp with the front and rear parking lights lit up. All are LED;s and it took a lot of trial and error to find the best brightness and color. I would like to share part numbers but they all came from chinamart which is all just a crapshoot. And now I am hoping I never have to buy anything from china regardless of any perceived benefit......I hope they ....  oh I can't say that.

[TommyBatchelor]

Thanks for the tip about the LED lights DS_PORTER. I'm in the process of installing these lumen lights : https://www.carid.com/1988-buick-reatta-headlights/lumen-4x6-rectangular-halo-led-headlights-2650089675.html and I am having an issue with the headlamps lowering. I found the headlight control module but I'm not experienced with wiring diagrams and am not sure which plug is c1. Is it the one with 4 wires with green colors? or the one with 5 wires that are red and yellowish? Any help is greatly appreciated! I don't want to do any unnecessary wiring (already did that once).

[DS_Porter 89 Burgandy]

Looking at my diagram in the manual it is:

    5 wire connector C1

    terminal C

    the yellow wire

Cut the yellow wire two or three inches from the connector to give yourself enough wire to work with.

Cap the wire that goes into the harness bundle.

Connect a wire to the yellow wire C from the terminal plug (about 16 gauge)

Run that wire to a good ground.

   That will ground the "retract" circuit allowing the headlight doors to close with full current just as the old incandescent filaments did.

I believe they were wired that way as a means of notifying the driver that a filament was burned out. As it has been stated before if we can't

tell if a headlight is out we should probably stop driving....

Let me know how it turns out

Dean Porter

[TommyBatchelor]

Headlights are fully functional, thanks Dean!

In case anyone was wondering...if you ground the green wire C on the other terminal plug you will short your battery and have to replace it. Luckily mine was new and in warranty and autozone replaced it without issue. 

Had to undo that wiring and ground the yellow wire C and now everything is working properly. Hopefully the reduced load will prevent the headlight switch from burning out anytime soon. Haven't had to replace it yet and it's been running halogen lights for a while.

Cheers

[DS_Porter 89 Burgandy]

Thanx for the successful report. Always happy to share what I know.

 

Pay it forward

[DAVES89]

Here's another way to do it without a aftermarket harness.

 

[Blue90]

6 hours ago, DAVES89 said:

Here's another way to do it without a aftermarket harness.

 

?

[jonlabree]

It's much safer with the aftermarket harness.

[2seater]

I went through a very long and involved project to be able to get the doors to close after adding relays for the headlights, and then the harness discovery, necessitated by LED's, and that worked with no cutting or splicing. All are valid, but the best thing about the harness is it improves any lighting system, no matter the type, by supplying the full system voltage, bypassing those skinny little ~16ga. wires. 

[sicknickclassics]

On 10/9/2020 at 3:44 PM, DS_Porter 89 Burgandy said:

Looking at my diagram in the manual it is:

    5 wire connector C1

    terminal C

    the yellow wire

Cut the yellow wire two or three inches from the connector to give yourself enough wire to work with.

Cap the wire that goes into the harness bundle.

Connect a wire to the yellow wire C from the terminal plug (about 16 gauge)

Run that wire to a good ground.

   That will ground the "retract" circuit allowing the headlight doors to close with full current just as the old incandescent filaments did.

I believe they were wired that way as a means of notifying the driver that a filament was burned out. As it has been stated before if we can't

tell if a headlight is out we should probably stop driving....

Let me know how it turns out

Dean Porter

 

[sicknickclassics]

90 Reatta here. I used the recommended harness to install LED's, but the lights stay on and will not retract. Tried installing without harness and they won't even light up at all. Prior to replacement, passenger HL was out... but they both opened and shut anyways. I haven run into any prior rigging.

 

Found this older thread about the yellow wire. I think on the 90 its a bit different. 2 of my 5 wires are yellow... 2 are orange and 1 black. Which 1 do I clip and ground? Both yellows? Or, is this option not available for me? 

 

Thanx!

[Ronnie]

All modules are the same with 2 yellow and 2 orange wires in the connector. You need to cut and ground the yellow wire on the end that goes to C1 on the module (see photo). It should be the yellow wire that goes to input C in your '90 FSM. Input C is labeled "Headlights On" in the '89 FSM as shown in the photo below. IF you are unsure of doing this, you should trace that yellow wire. It should go back to the headlight filiiment

 

I have never done this. This was done by another forum member who had the same problem after installing LED lights but I can't remember who it was. I looked at the wiring diagram in the FSM and it looks like it should work. I think it bypasses the headlight filament as a ground to satisfy the HCM so the doors will close.   

 

 

Quote

See page 8A-102-0 in the '89 FSM

 

On the Headlight Control Module connector C1 terminal C I cut the wire and capped the wire leading away from the HCM connector. I connected a 16ga wire to the severed wire C coming out of the plug and I ran that wire to a good ground.

   Up and Down then functioned correctly and the raise/lower switch also works correctly. You can do this fix regardless of what type of headlamp you are using and everything should work OK. 

 

[sicknickclassics]

6 hours ago, Ronnie said:

All modules are the same with 2 yellow and 2 orange wires in the connector. You need to cut and ground the yellow wire on the end that goes to C1 on the module (see photo). It should be the yellow wire that goes to input C in your '90 FSM. Input C is labeled "Headlights On" in the '89 FSM as shown in the photo below. IF you are unsure of doing this, you should trace that yellow wire. It should go back to the headlight filiiment

 

I have never done this. This was done by another forum member who had the same problem after installing LED lights but I can't remember who it was. I looked at the wiring diagram in the FSM and it looks like it should work. I think it bypasses the headlight filament as a ground to satisfy the HCM so the doors will close.   

 

 

 

Appreciate the response. Are you aware if this is a necessary conversion for the new relay harness to work as designed with LEDs?

[Ronnie]

The only harness I've owned had the standard H4 sockets on the end. I don't recognize the other sockets in the photos you posted.

[padgett]

I just use SilverStars which use the conventional socket and go up/down with no issue.

[Barney Eaton]

Just to confuse things it looks like Buick changed the wire colors at some time.  

The 1990 service manual shows  2 yellow and 2 orange coming from the firewall to the module. 

The plug going to the headlight motors has black ground, dark green and light green going to left motor,  dark green and grey going to the right motor

[sicknickclassics]

18 minutes ago, padgett said:

I just use SilverStars which use the conventional socket and go up/down with no issue.

Yah... I might end up doing the same if I can't figure this out. Put a call out to the manufacturer to see if I can't get a few answers. Thanx!

[sicknickclassics]

15 minutes ago, Barney Eaton said:

Just to confuse things it looks like Buick changed the wire colors at some time.  

The 1990 service manual shows  2 yellow and 2 orange coming from the firewall to the module. 

The plug going to the headlight motors has black ground, dark green and light green going to left motor,  dark green and grey going to the right motor

Def isn't standard wiring I'm used to over the years😅 is there an available link for a free service manual? Or am I gonna just have to order one?

[padgett]

Bishko has the '91 FSM on CD but only paper earlier.

[Barney Eaton]

This might help......... there was an early and late wiring version on the headlights.  That is noted at top left

Edited October 25, 2022 by Barney Eaton (see edit history)

[2seater]

I don't know what harness was used so I will just make this comment: I believe there are two general types of harness out there. Ours is a switched hot side, where B+ trips the relays. The other type of headlight uses a switched ground to do the same.  

 

I have installed three harnesses so far and all used the standard H4 socket as illustrated, however, the wire colors did not always match OEM.

Edited October 26, 2022 by 2seater (see edit history)

[sicknickclassics]

Update: for anyone else who runs into this problem, I located an easy solution. No cutting of wires or relay wiring harness required... plug and play!

 

Took a shot on this and it works perfectly. Sends the required current/signal back to the computer/switch. Time will tell if it sends too much current back to burn out the switch, but, it is designed for similar applications.

 

D-Lumina H4 9003 Canbus Decoder Anti Flicker Harness, LED Headlight Bulbs Resistor Decoders Error Free Conversion Kit, Computer Warning Canceller Capacitors (1 Pair) https://a.co/d/b7Tc4kH

[Ronnie]

Glad to hear it worked for you. The following question and answer from the Amazon website makes me wonder how much load it will put on the headlight switch. If it pulls enough current to need an aluminum box to protect the heat sink it might be too much.

 

Question:

Does the main unit easy get hot like many resistor out there?

 

Answer:

Thank you for your inquiry, it will not exist the get hot problem. The Decoder aluminum box is safety protect and heat sinking, high quality made the most advanced led decoder at all time. It is safe, easy installation and long lifetime.
By Blueseatec SELLER  on May 24, 2021