Barney Eaton

Reatta headlight

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A Reatta owner called today and said her mechanic installed LED headlights because she thought the one in the car were weak.

Now they are having trouble  with the lights..... I think closing.     Reading the service manual, it indicates the headlight module uses the low beam filament for ground in closing the headlights.

I recall at least one post where someone said they had problems after changing the headlight bulbs.

If the LED bulbs are the problem is there a fix/solution (something like adding a diode)  electrical problems are my downfall.

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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 saved it in case I ever needed it.  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.    If I knew for certain it worked correctly I would add it to the ROJ How-to Guides.

 

 

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. 

 

GROUNDED_HDM.jpg.a105d6ba92160fa8fc29d05e01e620d2.jpg

 

Edited by Ronnie (see edit history)

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I don't remember that fix either but I remember having some issues when I added two relays using hi-power conventional bulbs. Daves89 discovered his LED headlights worked fine after installing an aftermarket headlight relay harness. In that case I believe the ground is provided by the coil in the relay. Without a path to ground on shutdown the lights will stay open.

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Here is the Relay harness I ordered thru the Reatta Store

https://www.amazon.com/gp/product/B00BMN30HY/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1

 

I installed this in my car and made huge difference In brightness using the Silver Star Lights. With the harness lights are fed direct battery power and not thru the light switches or the small wires.

I hope this person did some research on the LED. The Truck Lights were the only ones people said had good pattern.

They may end up with poorer performance over all.

The Harness with the Silver Stars is the way to go for performance and cost.

I do drive my car often at night. Last 2 weeks I have at least 5 hours of night driving.

I hope the harness link helps.

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Dashmaster and 2seater are correct, an after market relay harness is the way to go. I used the relay harness in Dashmaster's link. It was an easy install and I use them with both the Truck lite [which is on the Black and Silver stars [which is on the Red]. The Truck lites need the harness so the car can read "off" and close the lights, and the Silver Stars need the relay harness to take some of the additional amperage strain off the headlight switch while delivering direct power from the battery. The headlight switch is then used for it's real intent, telling the car to turn "on" or "off" the headlights.

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I also tried LED lights other then Truck lites and I was very disappointed at the performance.  The "other" LED lights didn't light up the road well and also filled up with water. The Truck Lites are the best. But here is a draw back to LED lights. They throw off almost no heat at all which is great unless you are in a driving wet snow storm. Then the light starts to get covered over and you have to pull over and wipe them clean. Only happened once to me, and at first I didn't know what was happening, but when I pulled over and looked, I saw what happened.

Edited by DAVES89 (see edit history)

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I did not know about the grounding through the bulb when i first bought my car and i was changing the bulbs with power to the car

man did i get a surprise when i connected the plug to the bulb, headlamps up but switch off, and the headlamp slammed shut, as luck had it i was able to pull my hands out in time. but that could have been worse

SO DISCONNECT THE BATTERY WHEN CHANGING BULBS

 

also if running euro headlamps HELLA with standard wattage bulbs H4 55/65 do you think i would have to run the relay 

 

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That's a lot of wattage to run through the switch. I would get a relay harness.

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Doesn't go thru the switch,  there is already a relay in the system.

 

The schematic is just the top half of the page from the service manual....

You will note it is labeled "late production"(1990)  there is the first relay that is controlled by the headlight switch.

The second relay is for HI/LO beam switching

1990 LATE.jpg

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Thanks Barney

appreciate the info

 

Daves89  i agree about running it through the switch

as a point that is a standard wattage for later model headlights 

i even checked a H6054 halogen sealed beam has that wattage

but thankfully with Barneys info i have no worries

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I've tried HID and LED but like the overall pattern/brightness of Sylvania Silverstar Halogens better. NP opening & closing.

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I solved it by running a relay for the low and high beams. Simple fix and on the 89 there was even a spare relay spot In the fuse panel

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On 9/29/2019 at 7:41 AM, Barney Eaton said:

Doesn't go thru the switch,  there is already a relay in the system.

 

So if you have a '90 or '91 you don't need the aftermarket relay?🤔

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I'd need to study it and do not have a 90 anymore but my recollection is that the headlamp module senses current and when the headlamps hit the stop the current increases and it shuts down. Do not know why the headlamp current would make a difference. Do know there is an effect if the headlamp is not on/connected so maybe the current draw for the LEDs is too low. Is each one less than 37W ?

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As Barney mentioned, the addition of a relay to take the load from the headlight switch was a running change in 1990. Early production '90's don't have the relay so all power runs through the switch. I know mine did not and I burned up two expensive switches before I realized what was happening (80/100w headlights). IMHO the other side of that coin is the headlight wiring is too light gauge (16ga equivalent) for any sort of wattage upgrade and marginal for even the stock lighting. Just my opinion, but even stock headlights can benefit from a relay harness upgrade, partially for the load on the switch, but primarily to lessen the voltage drop in the stock harness, even with the late model relay addition which did not improve the wiring. As with Daniel, I too have separate hi and low beam relays, all homemade, but the aftermarket harness discovered later does the job without much sweat.

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I installed the harness from Dashmaster's link and the Lights are not working correctly. I'm hearing a click from popup headlight motors. When I turn on the lights they popup and come on but the bright's don't work and they wont go off. I kind of knew it wouldn't work. I plugged into the passenger side H4 connecter. It was easier/neater being close to the power source.  I'm thinking I'll have better luck with the driver side.  I'm just running Silverstar's at the moment. 

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" but the bright's don't work and they wont go off"   I think I know what you mean,  but this sentence says the Brights don't work and they won't go off......if they don't work, how can they go off?

Did the brights work before you started rewiring the light?

One thing to remember....the headlight harness goes to the drivers side first and then to the passenger side.  Sometimes the wires get broken inside the insulation and the drivers side might work but the passenger side does not...that is usually a bad wire.   Since you are new, the rest of the story is this happens when someone has routed the headlight wires incorrectly.   Each time the headlights open and close, the wires get flexed and they copper eventually breaks and if the ground breaks first neither the low or high beam will work.....  attached is a photo showing the CORRECT headlight wiring.   The cable come up between the fender and headlight casting.

it goes over the casting and plugs into the back of the bulb.

upstop III.jpg

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18 hours ago, PABrady said:

I installed the harness from Dashmaster's link and the Lights are not working correctly. I'm hearing a click from popup headlight motors. When I turn on the lights they popup and come on but the bright's don't work and they wont go off. I kind of knew it wouldn't work. I plugged into the passenger side H4 connecter. It was easier/neater being close to the power source.  I'm thinking I'll have better luck with the driver side.  I'm just running Silverstar's at the moment. 

I had one relay be bad from a harness similar to Dashmasters right out of the box. If I remember right one relay runs the on/off and the other relay is the brights. My relay issue was sometimes it would turn on and sometimes it wouldn't. Bought new relays and all was good. You may have a bad relay like I did. 

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I did not use the relays that come with the kit. I already had some 20A Bosch Relays from when I used to do Car Audio Installs that I used. I also mounted my on the Drivers Side by the fuse box instead of the battery side.

I have not had any issues since the install. Also not sure if they will work properly with only one light connected.

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Barney, everything was working fine before installing harness. My motivation for installing the harness was to eventually add LED lights without cutting wires. I am aware the passenger side feeds off the drivers, the wear and tear drivers H4 connector and how important the routing of the wires is. I probable know this because of all your post I read. Thanks!. Been working on Reatta's since 2009. Many other Buicks since 1983. I guess I don't post much because I'm terrible at putting my thoughts into words.  I currently have the harness removed and everything is working properly again. 

 

The troubleshooting steps I have taken:

Plugged into the driver side connector and replaced the relays. Still not working properly with the harness from Amazon. Other then deciding what connector you plug into, the install seems pretty idiot proof. I used the existing power source and ground terminals on the Passenger side near the battery. For the drivers ground I used the fender bolt to the body near the left headlight. 

 

I have a late 90 convertible that has the extra relays in the center console. I guess my question is the same as Retired w/Reatta. Is this hardness compatible with a late 90/91 Reatta? After reviewing this tread again I'm thinking no. Thanks

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Reconsider your ground. I used the Black ground box just behind the battery. Good time to clean all the connections in that box as well.

 

Edited by DAVES89 (see edit history)

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My 90 doesn't have the Black Ground Box. It does have 2 other ground points near the battery I used one of those. I did however clean every ground point I could find on the car to include the one on the engine. Did that a while back. SoCal car so there is virtually no corrosion. I will redo the ground on the drivers side. It would be nice to know if anyone with a late 90/91 car got this harness to work. 

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Wait sorry I do have that Black electronics ground Box. I will give that a try Thanks

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There are two ground studs in the radiator support in front of the battery and one on the fender side.

If you are having electrical problems make sure all three are tight.

Below is location from Service manual.... G100, G102 and isolated ground.....not sure why isolated ground is identified differently

Ground.jpg

Edited by Barney Eaton (see edit history)

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