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Relay wiring problem #1402934 03/15/13 08:57 PM 03/15/13 08:57 PM
Joined: Nov 2006 Posts: 730 Nampa, ID MadMatt OP super stock
MadMatt OP super stock Joined: Nov 2006 Posts: 730 Nampa, ID	I am trying to wire in relays to my headlight system and have a problem that is stumping me. With the relays wired in everything is fine with the lights off, fine with the park lights on, but when I switch on the headlights I get no headlights and my voltmeter drops from 15 volts to 10 volts with the engine running. I have checked and rechecked the wiring and everything appears to be correct. The only thing I found which seems weird to me is that with the relays just sitting on the bench they have continuity between the coil ground (terminal 85) and the relay trigger coil feed (terminal 86). Is this normal?? Could I have 2 brand new relays that are both defective? My knowledge of wiring is very basic, so ANY help or suggestions are appreciated! Some see the glass as half empty, some see the glass as half full. I just drink straight out of the bottle.

Re: Relay wiring problem [Re: MadMatt] #1402935 03/15/13 09:13 PM 03/15/13 09:13 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	I think you want the original wire to the headlights to go to the coil in (86) & the other end of that circuit (coil ground (85) to ground & the 2 other terminals one of them is connected to the headlights and the other one is connected to the power source (batt or alt) & when 86 is energized from the headlight switch & therefore groundes that circuit thru 85 that it connects the other 2 terminals (headlights/alt or batt) to each other. Someone will chime in with more detailed help live every 24 hour block of time like it's your last day on earth

Re: Relay wiring problem [Re: RapidRobert] #1402936 03/15/13 09:39 PM 03/15/13 09:39 PM
Joined: Apr 2005 Posts: 12,271 Overpriced Housing Central RobX4406 I Live Here
RobX4406 I Live Here Joined: Apr 2005 Posts: 12,271 Overpriced Housing Central	You can wire it like this, 85 is trigger, 86 ground, 30 power in, 87 power out. 85-86 is a chargeable field/solenoid, so it should have continuity. Sounds like you have a short somewhere. Where are you pulling power for the #30 relay terminal? I build headlight relay kits and use none of the old wiring, except to trigger the relays (minimal load)

Re: Relay wiring problem [Re: RobX4406] #1402937 03/15/13 10:58 PM 03/15/13 10:58 PM
Joined: Nov 2006 Posts: 730 Nampa, ID MadMatt OP super stock
MadMatt OP super stock Joined: Nov 2006 Posts: 730 Nampa, ID	Quote: You can wire it like this, 85 is trigger, 86 ground, 30 power in, 87 power out. 85-86 is a chargeable field/solenoid, so it should have continuity. Sounds like you have a short somewhere. Where are you pulling power for the #30 relay terminal? I build headlight relay kits and use none of the old wiring, except to trigger the relays (minimal load) I am using the original headlight power wire for the trigger source. For power I am pulling from the battery positive terminal. Grounds are grounded to core support and read good continuity to engine block. Some see the glass as half empty, some see the glass as half full. I just drink straight out of the bottle.

Re: Relay wiring problem [Re: MadMatt] #1402938 03/16/13 12:02 AM 03/16/13 12:02 AM
Joined: Jan 2003 Posts: 32,930 Grand Prairie,Texas stumpy I Win
stumpy I Win Joined: Jan 2003 Posts: 32,930 Grand Prairie,Texas	Do you have either high or low beams? You should be triggering the relays off the high and low beam feeds to the bulbs. Are you sure you have the out power from the correct relay terminal? 7627560-HeadlightRelayWiringDiagram.jpg (38 downloads)

Re: Relay wiring problem [Re: stumpy] #1402939 03/16/13 01:03 AM 03/16/13 01:03 AM
Joined: Nov 2006 Posts: 730 Nampa, ID MadMatt OP super stock
MadMatt OP super stock Joined: Nov 2006 Posts: 730 Nampa, ID	Quote: Do you have either high or low beams? You should be triggering the relays off the high and low beam feeds to the bulbs. Are you sure you have the out power from the correct relay terminal? No high beams or low beams. And since the voltage drop happens I think it's clear that the relays are being triggered. I'm taking the power out to the headlights from terminal 87. Some see the glass as half empty, some see the glass as half full. I just drink straight out of the bottle.

Re: Relay wiring problem [Re: MadMatt] #1402940 03/16/13 10:06 AM 03/16/13 10:06 AM
Joined: Jan 2003 Posts: 6,393 Abilene, Texas F fastmark master
fastmark master F Joined: Jan 2003 Posts: 6,393 Abilene, Texas	This topic is perfect timing for me right now. I'm trying to do the same thing shortly. Where do you get these relays and where do most people mount them? I guess you wire the A/C compressor the same way?

Re: Relay wiring problem [Re: fastmark] #1402941 03/16/13 12:56 PM 03/16/13 12:56 PM
Joined: Jan 2003 Posts: 32,930 Grand Prairie,Texas stumpy I Win
stumpy I Win Joined: Jan 2003 Posts: 32,930 Grand Prairie,Texas	Any parts store will have the relays.

Re: Relay wiring problem [Re: MadMatt] #1402942 03/16/13 01:05 PM 03/16/13 01:05 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	I'm assuming you have 1 relay for both hi/low beams. I'd think if the headlight power wire TO the dimmer switch is connected instead to 85 & 86 is permanently grounded and 30 is connected to the battery & 87 is connected to the upstream side of the dimmer switch where the headlight power in wire originally was connected to, that you'd be good. On a related note I would highly suggest powering "30" from the alt rather than the battery live every 24 hour block of time like it's your last day on earth

Re: Relay wiring problem [Re: RapidRobert] #1402943 03/16/13 01:15 PM 03/16/13 01:15 PM
Joined: Nov 2006 Posts: 730 Nampa, ID MadMatt OP super stock
MadMatt OP super stock Joined: Nov 2006 Posts: 730 Nampa, ID	Quote: I'm assuming you have 1 relay for both hi/low beams. I'd think if the headlight power wire TO the dimmer switch is connected instead to 85 & 86 is permanently grounded and 30 is connected to the battery & 87 is connected to the upstream side of the dimmer switch where the headlight power in wire originally was connected to, that you'd be good. On a related note I would highly suggest powering "30" from the alt rather than the battery Actually, I have 1 relay for low beams and 1 for high beams. Each uses the respective original head lamp power wire as the trigger source. I'm pulling power from the battery terminal, but that is the same terminal the alternator is hooked to, so it should not make a difference. Some see the glass as half empty, some see the glass as half full. I just drink straight out of the bottle.

Re: Relay wiring problem [Re: MadMatt] #1402944 03/16/13 01:33 PM 03/16/13 01:33 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	Quote: I'm pulling power from the battery terminal, but that is the same terminal the alternator is hooked to, so it should not make a difference. Correct, no difference on the problem at hand. Well either both relays are bad (not impossible but unlikely) or it's not wired right & from your descrip it's good & it is a simple 4 wire system unless we're missing something & it sounds like we are. I'd start by checking both of the relays with your VOM & put fire to 86 & ground 85 (I may have 85/86 backwards & may not even make a difference) & see if that makes 30 & 87 make continuity & if so then each 87 on the relays should be going out to each respective hi/low beam. EDIT you have the wire from the high beams going rearward to 87 on one relay and the wire from the low beams going rearward to 87 on the other relay correct? Batt power to 30 on both. 85 is grounded on both and 86 on one relay gets fire from the high beam dimmer switch wire and 86 on the other relay gets fire from the low beam dimmer switch wire? Last edited by RapidRobert; 03/16/13 02:05 PM.

Re: Relay wiring problem [Re: MadMatt] #1402945 03/16/13 02:27 PM 03/16/13 02:27 PM
Joined: Mar 2007 Posts: 3,277 West Coast, USA jbc426 master
jbc426 master Joined: Mar 2007 Posts: 3,277 West Coast, USA	This may help... http://www.classictruckshop.com/clubs/earlyburbs/projects/bosch/relay.htm 1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's 1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)

Re: Relay wiring problem [Re: jbc426] #1402946 03/20/13 01:46 AM 03/20/13 01:46 AM
Joined: Mar 2003 Posts: 3,609 Southern Oklahoma wildman340 master
wildman340 master Joined: Mar 2003 Posts: 3,609 Southern Oklahoma	Maybe this will too: 7632956-headlight-relays.gif (52 downloads) 1974 Dodge Dart Sport 340 4 Spd Endless Project 1999 Ram 1500 CC 5.2 5 speed

Re: Relay wiring problem [Re: MadMatt] #1402947 04/13/13 08:06 AM 04/13/13 08:06 AM
Joined: Jan 2005 Posts: 3,699 Newport, Mi Evil Spirit master
Evil Spirit master Joined: Jan 2005 Posts: 3,699 Newport, Mi	I saw this post while looking for another one. All the replies assume that the dimmer switch is switching the positive battery polarity. They don't - my 99 Dakota for example, fuses the hot, which goes directly to the headlamp, and switches ground through the dimmer to select low/high beams. Free advice and worth every penny... Factory trained Slinky rewinder.........

Re: Relay wiring problem [Re: stumpy] #1402948 04/13/13 02:02 PM 04/13/13 02:02 PM
Joined: Feb 2010 Posts: 18,493 Granite Bay CA Kern Dog Striving for excellence
Kern Dog Striving for excellence Joined: Feb 2010 Posts: 18,493 Granite Bay CA	Bob and I tried the relay idea with the Charger. It didn't work out well. The low beams came on. The H/L doors opened...But the doors would not close nor the low beams shut off with the switch, UNLESS the high beams were clicked on. Sometimes the headlight doors would open and close when you turn the ignition/key on. I ordered a new harness from Evans wiring. The goal of using relays was to have safer power to the lights. The new harness at least puts me back to a stock UN molested condition.

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