Please Help - Strange 12v relay issue

Turbogus

Turbogus

Active member
I've wired up my other DD with relays as I've done with so many vehicles over the years including my '78 CJ5 'Black Betty'. The trouble that I'm having is with verified wiring to/from the Ford PDB I'm using is initially I have 12 output availablefor low beams. Then suddenly 3v down to 1.8v WTF? One headlight remains lighted and the other is extremely dim. Hi beams function correctly.
I've wired my headlights to the PDB with a junction for left and right low beams and a separate line for hi beams. All connections are twisted, soldered and seal in heat shrink tubing. I must have gone wrong somewhere but for the life of me, I can't seem to figure it out.


Thanks in advance for any help on this.


Gus
 
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Check the ground contacts. It is possible if the ground to one light is bad it creates a series connection between the lights.


Never look down on anyone unless you are helping them up - Jesse Jackson
 
Thanks for chiming in JpN, hope you've been keeping well. I'm going to check the grounds this afternoon. Also After I went to bed I was thinking about this and it occurred to me that the headlights on This setup may be on a fused circuit. On 'Black Betty' they're using the same PDB.
 
Okay grounds are solid and I found that one of the headlights had the wiring reversed for ground and hi beam. Also different wattages of H4. They are working now when switching from Lo to Hi beam there's no issue, but switching back from Hi to Lo beam and they don't reset to Lo unless I cycle the headlight switch.
 

All new relays? High beam may be bad? Did you try swapping?

How about a basic sketch of wiring? Number the pins accordingly. I'm guessing look at the high beam pins 85 and 86. 85 ground and 86 signal from high beam if low 85 ground is connected to high 86 signal this may create this situation.


Regards,
JPNinPA

Never look down on anybody unless you're helping them up. -Jesse Jackson
 
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Doing well BTW and thanks for asking!!


Regards,
JPNinPA

Never look down on anybody unless you're helping them up. -Jesse Jackson
 

This is an approximation of the wiring;
lightrelay2_b2bb41adbe106838a1fd8a6856f940c997e4bba1.jpg

I have a bag of relays from the other projects over the years. the ones I'm using now are 40 amp that I purchased new last year. I'm beginning to suspect the light switch but, I may go with a foot dimmer before this is over. Sorry for my indelicacy sometimes I guess I get carried away by my frustration, especially in this case where I've done this conversion so many times before without any difficulty.
[Edit] Sometimes I suppose the old 'inner Marine' gets the better of me, occasionally when I've drunk to excess he comes to the fore, I'm working on it.
 
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Even if I returned to the Flösser 140/90 H4's I note that I'm only pushing a little over 23 Amps which is well within the limits of the relays that I am using.
 

The wiring looks good. The only question is the G1 point. Is that a single point? Or is it seperate points. If a single point a bag ground can allow voltages to float and keep the relay closed


And yes the multifunction switches do go bad.




Never look down on anyone unless you are helping them up - Jesse Jackson
 
This is a new Multifunction switch, but give their design, I don't trust them. I have most of the underhood grounds going to a bus bar that connects with an 8 gauge cable to the negative battery post.
 
I took the foot dimmer from my Jeep and temporarily wired it in and they started working properly. Must be an overtaxed circuit somewhere. Made the wiring permanent (soldered and shrink wrapped) and got a new dimmer for my 5
 
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