The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > Info Center > FAQ Truck Tech > 67-72

Web 67-72chevytrucks.com


Closed Thread
 
Thread Tools Display Modes
Old 02-06-2006, 07:36 AM   #1
Tx Firefighter
Watch out for your cornhole !
 
Tx Firefighter's Avatar
 
Join Date: Jun 2003
Location: Texas
Posts: 14,059
Headlight relay mod revisited...my way to do it and save some money

I was wandering around looking under the hood of junk cars, scavenging hose clamps and other usefull trinkets when I spotted the perfect thing.

On a FWD Mopar puke car, late 80's, early 90's there is a perfect little bracket with two Bosch style relays on the fenderwell.

These are the exact relays you need to do the headlight relay mod and not have to order them or buy them new. A Bosch relay is a Bosch relay. These were priced perfectly, free.

Here's some pics of what I'm talking about...

If you do this mod, please do it right, so it's reliable.

I posted a picture of good quality crimping tools. Those 4 dollar do-it-all electrical tools suck. Spend 25 bucks and enjoy the good life.

I also posted a picture of a neat tool I use. It's a miniature butane torch. I originally saw the Boyd's guys using them on TV. My wife picked one up for me at Home Depot. It's a godsend for heat shrink tubing in tight areas.

Finally, there is a picture of a finished connection. Notice there are no connectors with colored plastic sleeves. Remove the sleeve and expose the bare connector. Then crimp with a good tool. Next, solder the connection to the terminal. Finally, cover with heatshrink.

Matt covered the basics of this mod in his post, I'm just elaborating on a good way to do it even cheaper.
Attached Images
     
__________________
Kevin -

My Instagram

Last edited by Tx Firefighter; 02-06-2006 at 07:38 AM.
Tx Firefighter is offline  
Old 02-06-2006, 10:59 AM   #2
70c10
67-72 Addict!
 
70c10's Avatar
 
Join Date: Feb 2002
Location: The TAX State!
Posts: 7,857
Re: Headlight relay mod revisited...my way to do it and save some money

Nice write up!. How did you know which terminals to hook up the headlight wires???. They look slick.
__________________
Jim

1970 C/10 Fleetside w/Ghost Flames
Lowered 4.5" front and 4" rear (Raked)
355/350 Turbo w/shift kit
10" Redneck Performance Verter w/2500 stall
Hooker Super Comps part#2808-1
Performer RPM Air-Gap
12 Bolt w/3:73 gears- Eaton Posi
Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads
70c10 is offline  
Old 02-06-2006, 11:08 AM   #3
Tx Firefighter
Watch out for your cornhole !
 
Tx Firefighter's Avatar
 
Join Date: Jun 2003
Location: Texas
Posts: 14,059
Re: Headlight relay mod revisited...my way to do it and save some money

Go here, and look at page 5. I just printed the page off for my tech notebook that I keep on my workbench.

http://sonolithics.com/files/bosch.pdf

Warning, not for the dial up guys, that's a big PDF file.
__________________
Kevin -

My Instagram
Tx Firefighter is offline  
Old 02-06-2006, 11:57 AM   #4
Tx Firefighter
Watch out for your cornhole !
 
Tx Firefighter's Avatar
 
Join Date: Jun 2003
Location: Texas
Posts: 14,059
Re: Headlight relay mod revisited...my way to do it and save some money

The sonolithics lists the terminal numbers on the relays, and if you look closely at the bottom of the relay themselves, the same numbers are on them.

Also, I swapped the driver's side headlight plug for a spare passenger side plug I had laying around. Once you cut the original wiring apart, you will be left with two extra unused wires on the left headlight plug. The right headlight plug is exactly the same, but doesn't have the two unused wires hanging off of it. I did this strictly for a neater appearance. I didn't want two little short stubs of cut off wires sticking out and looking shoddy.
__________________
Kevin -

My Instagram
Tx Firefighter is offline  
Old 02-06-2006, 12:25 PM   #5
shifty
Registered User
 
shifty's Avatar
 
Join Date: Mar 2005
Location: Atlanta
Posts: 12,853
Re: Headlight relay mod revisited...my way to do it and save some money

Great stuff. Might want to include a link back to the original wiring explanation thread just for the purpose of archival. Curious - what car exactly did it come out of? (rough estimate?)
i went to the junkyard today and just wanted to let everyone know - you can find the relay setup that Tex is talking about on 92-94 Dodge/Plymouth's : Sundance/Duster/Shadow models and I think also on the Summit as well. The relay setup is bolted to the driver's side shock/strut tower with what looked like a 1/2" or 13mm bolt. I seriously found at least 10 of them in good shape - and I didn't even make it all the way through the Mopar section of my local Pull-A-Part, so they are definitely out there to be had."
__________________
I'm probably still around lurking. Drop me a PM.

Last edited by krue; 05-30-2007 at 11:26 PM.
shifty is offline  
Old 02-06-2006, 12:42 PM   #6
Tx Firefighter
Watch out for your cornhole !
 
Tx Firefighter's Avatar
 
Join Date: Jun 2003
Location: Texas
Posts: 14,059
Re: Headlight relay mod revisited...my way to do it and save some money

Late 80's or early 90's FWD Mopar with 2.2 or 2.5 engine. I think it was a Sundance or similar.
__________________
Kevin -

My Instagram
Tx Firefighter is offline  
Old 02-06-2006, 12:47 PM   #7
jhow66
Registered User
 
jhow66's Avatar
 
Join Date: Jun 2002
Location: Knoxville Tenn.
Posts: 3,058
Re: Headlight relay mod revisited...my way to do it and save some money

Here's how I set up my son's Blazer (orangeuavol).
Attached Images
 
__________________
56 Chevy Bel-Air 2dr. HT (purchased new)
71 Chevy Cheyenne SWB PU (502HO)
65 GMC short bed step--work in progress and my gofer
jhow66 is offline  
Old 02-06-2006, 05:27 PM   #8
69TowRig
Senior Member
 
Join Date: Jan 2005
Location: Raleigh, NC
Posts: 882
Re: Headlight relay mod revisited...my way to do it and save some money

Quote:
Originally Posted by 67chevemall
Man I have been lookn for a pair of those crimpers for toooo long now.
Home Depot has started carrying more "REAL" electrical tools. I know they have those there.

Personally I use a GreenLee ratcheting cyclical crimper. I have the dies for insulated and uninsulated terminals. Works like a champ and you don't get a hand cramp from using them.

Also, I have noticed that LMC is now selling a supposedly "plug-in" upgraded headlight relay harness. I believe it was $29.99
__________________
-Chris
Building a stripper, one part at a time: 1969 K5, 307, 3spd, 3 seats, hard top. Added Pwr Discs, Pwr Steering, Aux Battery, T-case Skid, Lighted Sidemarkers, HEI, Lock-Right Diff, ECE Class IV Hitch, 32" MT/Rs. Parts to Install: Hand Throttle, Console, Tow Hooks, Dual Horns, AM-FM, Dealer Swing-Away Tire Carrier, Gas Tank Skid.
Click HERE for Blazer pics. Click HERE for Nissan Frontier stuff.

Last edited by 69TowRig; 02-06-2006 at 05:57 PM.
69TowRig is offline  
Old 02-06-2006, 05:54 PM   #9
Tx Firefighter
Watch out for your cornhole !
 
Tx Firefighter's Avatar
 
Join Date: Jun 2003
Location: Texas
Posts: 14,059
Re: Headlight relay mod revisited...my way to do it and save some money

Mine are Klein brand. They cost 22 dollars a few years back. Worth every cent too.

You can get them online for 20 bucks.

http://www.mytoolstore.com/klein/1005.html
__________________
Kevin -

My Instagram
Tx Firefighter is offline  
Old 02-06-2006, 06:52 PM   #10
72MARIO
Registered User
 
72MARIO's Avatar
 
Join Date: Nov 2000
Location: Huntsville Ontario Canada
Posts: 3,986
Re: Headlight relay mod revisited...my way to do it and save some money

I have a hard time understanding how this works. Page 5 is what I should be looking at for the directions ? Any specfic info on how to do this to our trucks ?
__________________
1968 Suburban numbers matching all original truck now equipped with 6.0/4L80 on Accuair
http://67-72chevytrucks.com/vboard/s...d.php?t=625017
1967 C/20 6.0/4L80 Roofing Truck
1990 V2500 Suburban "Plow Truck"
2005 TAHOE DD
72MARIO is offline  
Old 02-06-2006, 06:56 PM   #11
Russell
Professional Grade
 
Russell's Avatar
 
Join Date: May 2003
Location: Fort McMurray, Alberta
Posts: 7,916
Re: Headlight relay mod revisited...my way to do it and save some money

Oh, and here is how I did mine up:

http://www.zieglerdigital.ca/public/...tricfans01.jpg

I haven't run the power wire from the firewall distribution block to the core support dist block yet, but other than that, its all ready to go.

Still plan to buy an H4 European style bosch headlight conversion kit for the truck yet, both sealed beams have one of their beams burnt out.

I have an H4 kit in my 77, without the relays, and dang is it ever nice! Can't wait to see it done up with the relays!
__________________
1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

Last edited by Russell; 02-06-2006 at 06:56 PM.
Russell is offline  
Old 02-06-2006, 07:19 PM   #12
jhow66
Registered User
 
jhow66's Avatar
 
Join Date: Jun 2002
Location: Knoxville Tenn.
Posts: 3,058
Re: Headlight relay mod revisited...my way to do it and save some money

Quote:
Originally Posted by Tx Firefighter
jhow66, where can I get one of those inline circuit breakers at? Anything OEM that I can get at the junkyard?
Got mine at NAPA. Got the ticket somewhere--will look up the number for you.
__________________
56 Chevy Bel-Air 2dr. HT (purchased new)
71 Chevy Cheyenne SWB PU (502HO)
65 GMC short bed step--work in progress and my gofer
jhow66 is offline  
Old 02-06-2006, 07:29 PM   #13
roger0080
Registered User
 
Join Date: Nov 2000
Location: St. Paul, MN, USA
Posts: 609
Re: Headlight relay mod revisited...my way to do it and save some money

TxFirefighter, did these have any female plastic connector housings attached to the relays from the MOPAR donor car or did they attach like you show in the photo?
__________________
72 Chev C-10 90% restored (former AZ truck) ...
71 Chev K-20 Cheyenne my vacation crusier...
72 Chev C-10 Now retired and striped after many faithful miles...
72 GMC 1500 Retired to the junk yard after bought new in '71...
roger0080 is offline  
Old 02-06-2006, 08:28 PM   #14
Tx Firefighter
Watch out for your cornhole !
 
Tx Firefighter's Avatar
 
Join Date: Jun 2003
Location: Texas
Posts: 14,059
Re: Headlight relay mod revisited...my way to do it and save some money

72Mario. Basically, here's the deal. Power must travel from your battery all the way to the light switch then back to the lights. This induces a lot of resistance and voltage drop. The end result is that far less than battery voltage reaches the lights, causing them to not be as bright as they could be.

The relay mod changes all this. It makes it to where the power only has to go from the battery through the relay on the core support and then to the headlights. This is a much shorter pathway with fewer sources of resistance. The end result is full battery power reaches the headlight and that gives 30 to 50 percent improvement in headlight output.

Mad electrical has a great article on their website which explains this fully, in easy to understand language.
__________________
Kevin -

My Instagram
Tx Firefighter is offline  
Old 02-06-2006, 08:34 PM   #15
Tx Firefighter
Watch out for your cornhole !
 
Tx Firefighter's Avatar
 
Join Date: Jun 2003
Location: Texas
Posts: 14,059
Re: Headlight relay mod revisited...my way to do it and save some money

Here is the link to MAD's article. There are two pages with lots of pictures.

http://www.madelectrical.com/electri...adlights.shtml

Roger, the Mopar used a nice plug with the wires securely positioned. Only thing was, the owner had stripped this car of it's entire wiring harness. So, I was able to get the relays, but not the connectors. I'm sure you'd be able to get them off your donor though.
__________________
Kevin -

My Instagram
Tx Firefighter is offline  
Old 02-06-2006, 11:39 PM   #16
bigblock73
yeller
 
bigblock73's Avatar
 
Join Date: Oct 2001
Location: Twin Cities
Posts: 13,657
Re: Headlight relay mod revisited...my way to do it and save some money

Quote:
Originally Posted by 72MARIO
I have a hard time understanding how this works. Page 5 is what I should be looking at for the directions ? Any specfic info on how to do this to our trucks ?
Mario, maybe this will help (I hope)

http://www.73-87.com/7387garage/exte...ight_relay.htm
bigblock73 is offline  
Old 02-07-2006, 12:27 AM   #17
Tx Firefighter
Watch out for your cornhole !
 
Tx Firefighter's Avatar
 
Join Date: Jun 2003
Location: Texas
Posts: 14,059
Re: Headlight relay mod revisited...my way to do it and save some money

Quote:
Originally Posted by Premium72
where they show the "junction box" what is that...that the block on the passenger inner fender next to the battery tray?. this may solve the issues im having now. thanx. awesome write up.
It's a phenolic deal with a metal stud made into it.

A wire comes from the positive battery terminal to this block. From there, two wires travel across the core support and into the trucks wiring harness.

If you're having troubles in this area, check your fusible links. Use a testlight and also try to stretch them. Sometimes, a fusible link fails, but still looks fine. They go bad inside the insulation.
__________________
Kevin -

My Instagram
Tx Firefighter is offline  
Old 02-07-2006, 01:21 AM   #18
jhow66
Registered User
 
jhow66's Avatar
 
Join Date: Jun 2002
Location: Knoxville Tenn.
Posts: 3,058
Re: Headlight relay mod revisited...my way to do it and save some money

To Tex.: here is the item # for circuit breaker at NAPA--BK 7823105
Attached Images
 
__________________
56 Chevy Bel-Air 2dr. HT (purchased new)
71 Chevy Cheyenne SWB PU (502HO)
65 GMC short bed step--work in progress and my gofer
jhow66 is offline  
Old 02-07-2006, 01:35 AM   #19
jhow66
Registered User
 
jhow66's Avatar
 
Join Date: Jun 2002
Location: Knoxville Tenn.
Posts: 3,058
Re: Headlight relay mod revisited...my way to do it and save some money

By the way DO NOT use a fuse in your headlight circuit between the power source and your relays. Why? Pitch black road--75MPH-- hit a bump or whatever--light wire shorts and blows fuse--no lights and a curve coming up that you cannot see--ouch. Circuit breaker--lights goes out-comes back on -goes out and so forth. The circuit breaker in the light switch will protect the wires from light switch to the relays.
__________________
56 Chevy Bel-Air 2dr. HT (purchased new)
71 Chevy Cheyenne SWB PU (502HO)
65 GMC short bed step--work in progress and my gofer
jhow66 is offline  
Old 02-11-2006, 11:53 PM   #20
project1971
Registered User
 
project1971's Avatar
 
Join Date: Apr 2003
Location: Oklahoma City
Posts: 605
Re: Headlight relay mod revisited...my way to do it and save some money

Alright guys here is another source for a relay panel. I got mine from work actually, I work for Ford and had some wire looms laying around the entire things. Had some small relay boxes i had set aside for later projects and i ended up using one of them for my elec cooling fans (which also got from work they came off a wrecked Escape) They are in a plastic case with a removable top and you can replace the the relay if need be very easily. These can be found in most late model Ford vehicles like '97-03 F-150's. Inside the truck on the pass side under the panel on top of the dash is probably the easist to get to. I will take pic of it tomorrow and post them and pics of the cooling fans also they work great. I can have it sitting still running and turn the fans on and cools it so well the guage registers just below the normal level on the cold side! I have a box full of those relays I take them out of every fuse panel i replace to keep as spares or other projects.
__________________
2008 Ford FX2 Screw
1971 C10 project in shop now!
2004 Pontiac Grandam (wifes)
2000 Cavalier z24 (gas saver)
project1971 is offline  
Old 02-12-2006, 01:42 PM   #21
project1971
Registered User
 
project1971's Avatar
 
Join Date: Apr 2003
Location: Oklahoma City
Posts: 605
Re: Headlight relay mod revisited...my way to do it and save some money

ok here is the pics i promised keep in mind they are off a Ford but who cares if it works right?!?
Attached Images
   
__________________
2008 Ford FX2 Screw
1971 C10 project in shop now!
2004 Pontiac Grandam (wifes)
2000 Cavalier z24 (gas saver)
project1971 is offline  
Closed Thread

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 10:01 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.
Copyright 1997-2013 67-72chevytrucks.com