Headlight relay thread

[zac_f83]

I did a quick search in this forum and found very little on the subject-

I want to relay my headlight harness and need to know which wires go where? I had help from a friend on my old 87GT and it made a HUGE difference and want to do it in my 83 GT so I can actually use the brights.. (can't use them as after about 3-5 minutes all the lights shut off..)

I have some 30/40amp Bosche style 5 prong relays I plan to use.. (2 - 1 for low beams 1 - for high's - can get them off eBay though)

So how is it done? Which wires do I tie into? Any help would be great thanks!

[FoxChassis]

Some of these threads should have what you're looking for: http://vb.foureyedpride.com/tags.php...dlight+upgrade

[BrianM]

Mike did a great write up on his site.

http://mikemartinelli.com/index.php?...-relay-upgrade

[zac_f83]

Thanks 1 thread from 2004 - link - helps but which wires from the relay go to which wires in the car's harness? I know 2 wire's from each relay go to the battery + and a ground but which are they...?




http://vb.foureyedpride.com/showthre...tions-problems

[zac_f83]

Mike did a great write up on his site.

http://mikemartinelli.com/index.php?...-relay-upgrade

HOW did I not see this! SAVER OF LIFE you are!

[zac_f83]

hmm relaying the headlights didn't go as planned - both driver side lights are on all time and bright as all get out - the passenger side is dim and works as it should/did...

I think I see my problem I have 5 prong relays and the write up uses 4 prong.. :-(

I wired everything as per the link (DIY relay post) below

Need help guys need to fix this tomorrow morning!

http://mikemartinelli.com/index.php?...-relay-upgrade

[ZephyrEFI]

I think I know pretty well how a relay works, but WTF would a fifth prong be for??!

[Mike Croke]

hmm relaying the headlights didn't go as planned - both driver side lights are on all time and bright as all get out - the passenger side is dim and works as it should/did...

I think I see my problem I have 5 prong relays and the write up uses 4 prong.. :-(

I wired everything as per the link (DIY relay post) below

Need help guys need to fix this tomorrow morning!

http://mikemartinelli.com/index.php?...-relay-upgrade

I think I know pretty well how a relay works, but WTF would a fifth prong be for??!

On a "4 prong" relay, #85 & #86 are the low current small wire trigger connections, #85 is usually wired to ground and #86 receives 12VDC when you want the device to switch ON. The other terminals are #87 and #30. Generally, the always-hot 12VDC supply-from-the-battery wire goes to #30. The device you are trying to turn ON/OFF gets connected to #87. When the relay is OFF, #87 is also OFF.

On the typical "5 prong" relay, the extra is a normally ON connection. When your switch is OFF, that extra terminal is getting the always-hot 12VDC from #30. When your switch is ON, #30 is disconnected from #87A and is switched to #87.

[zac_f83]

I think I know pretty well how a relay works, but WTF would a fifth prong be for??!

LOL I'm not sure I usually have a friend help that knows relays BUT he is busy and 4 hours from me so it's just me - I have pics of what happens - I moved the ground to the batt and nothing changed - removing the ground changed nothing either..

Here is what it says in the write up -
Pole 85 - Ground - Black wire
Pole 30 - + to Batt - Red wire
Pole 86 - lead from switch under dash - Blue wire
Pole 87 - lead to head lights in front of car - Yellow wire

Here is how I have it wired -
Pole 87 - lead from switch under dash - Blue wire
Pole 87A - Red wire to batt +
Pole 86 - white wire not used currently
Pole 85 - Ground to batt - Black wire
Pole 30 - lead to head lights in front of car - Yellow wire

Here are pics -



Head switch off - just connect the batt and these 2 light up all time


Head light switch on - passenger side is dimmer than in the pic but the low/high beam functions as it should

[zac_f83]

On a "4 prong" relay, #85 & #86 are the low current small wire trigger connections, #85 is usually wired to ground and #86 receives 12VDC when you want the device to switch ON. The other terminals are #87 and #30. Generally, the always-hot 12VDC supply-from-the-battery wire goes to #30. The device you are trying to turn ON/OFF gets connected to #87. When the relay is OFF, #87 is also OFF.

On the typical "5 prong" relay, the extra is a normally ON connection. When your switch is OFF, that extra terminal is getting the always-hot 12VDC from #30. When your switch is ON, #30 is disconnected from #87A and is switched to #87.

So based on this how is it supposed to be wired? from reading the relay info you attached I have to de-pin the pigtails and arrange them in the correct fashion maybe?

[Mike Croke]

LOL I'm not sure I usually have a friend help that knows relays BUT he is busy and 4 hours from me so it's just me - I have pics of what happens - I moved the ground to the batt and nothing changed - removing the ground changed nothing either..

Here is what it says in the write up -
Pole 85 - Ground - Black wire
Pole 30 - + to Batt - Red wire
Pole 86 - lead from switch under dash - Blue wire
Pole 87 - lead to head lights in front of car - Yellow wire

Here is how I have it wired -
Pole 87 - lead from switch under dash - Blue wire
Pole 87A - Red wire to batt +
Pole 86 - white wire not used currently
Pole 85 - Ground to batt - Black wire
Pole 30 - lead to head lights in front of car - Yellow wire

Only one of your wires is connected correctly. For this application, nothing should be connected to #87A ever. Ignore #87A, attach nothing to #87A.

This is correct:
Here is what it says in the write up -
Pole 85 - Ground - Black wire
Pole 30 - + to Batt - Red wire
Pole 86 - lead from switch under dash - Blue wire
Pole 87 - lead to head lights in front of car - Yellow wire

[zac_f83]

Only one of your wires is connected correctly. For this application, nothing should be connected to #87A ever. Ignore #87A, attach nothing to #87A.

This is correct:
Here is what it says in the write up -
Pole 85 - Ground - Black wire
Pole 30 - + to Batt - Red wire
Pole 86 - lead from switch under dash - Blue wire
Pole 87 - lead to head lights in front of car - Yellow wire

OK thanks! looks like I'm de-pinning and re-arranging the pigtails haha

[zac_f83]

All is fixed!

This is correct like Mike and my Friend confirmed:

Pole 85 - Ground - Black wire
Pole 30 - + to Batt - Red wire
Pole 86 - lead from switch under dash - Blue wire
Pole 87 - lead to head lights in front of car - Yellow wire
Pole 87A - not used

This way and having matching wire colors on 5 prong relays requires de-pinning the pig tails and rearranging them in the correct fashion