Low voltage in headlight plug

[98SF19]

Drivers side headlight was looking ******** dim so I checked last night and it's putting out 11.7 volts. Motor off battery output was 12.45 or so and checking voltage drop between plug positive and battery positive gave about 0.64 volts. Does this mean it's NOT a ground issue? It's worth noting that I currently have a small length of 18 awg wire (4" or so) attached at each ground point on either side of headlights (near hood strut attachment) that are not attached to anything on the free end. These are eventually going to be soldered to the plugs on the wiring harness I haven't yet installed (have 1 or 2 more solder joints left to make).

So here's my question for that: Is there any variance in relays as to what input voltage is needed to open them? IE, would the 11.7 volts be plenty to trigger most relays on the market? If the low voltage OEM plug was on passenger side, it would be moot, but I made the harness so that it would attach to the driver's side oem plug, which is the one that's low. I honestly haven't gone out and stretched out the harness to see if I could reverse it, I just dont want the relays anywhere near the exhaust manifold.

Thanks

 

[stephen newberg]

The tolerance on relays will, of course, vary by manufacturer, but in general I would expect 11.7 volts to be enough to trigger a relay in a nominal 12 volt system when it is new. As it ages, that could change, and these cars are getting old.

Of more concern, though, is why you only have the 11.7 volts reading, as that indicates a resistance loss of about half a volt somewhere in a not all that long stretch of wiring, and that is likely to be way out of spec, so I would want to find it and fix it before it becomes greater and works its way into the potential for a fire. Pun intended.

pax, smn

 

[98SF19]

Thanks Stephen. Yes, it's an issue that needs resolved. I began tracking down wiring yesterday - took out battery and battery cradle and began pulling back the wrap, also dismantled mega fuses in front and next to battery - found nothing. There was a bundled "tee" section of wiring under and behind the battery that seemed to look slightly "melted" but loosening the wrap revealed it was only superficial. The user Fourofdiamonds posted a couple years ago that his AC was fixed when he found some fried wiring up front and replaced it. My AC hasn't worked in a while (shop says they need working RCC before they can continue diag) and now this. As far fetched as it might be, I'm hoping that the solution for one will fix the other. Worst case scenario, I get a wiring diagram from shorod and just re-run the wires, bypassing bundle. I think I'll message him right now actually . . .

I'm sure the pros have better tools to detect high resistance along wires than I do. So I'll plan on getting in this week sometime. We need a Nimz down here in Florida.

 

[SHOZ123]

You need a better relay wire loom for the headlights. Ford used too small of wire.

http://www.ebay.com/itm/Headlight-T...ess-/121673871249?hash=item1c5453ef91&vxp=mtr

 

[98SF19]

Thanks Paul. If I hadn't already made up my own harness, I might be a taker (nothing like getting a bit stoned from the lead/tin smoke in poorly ventilated areas). If I wasn't clear, the current setup is bone stock. I question whether the harness above is truly for 9007 bulbs or 9004 since both the picture and the diagram show the black lead coming from a side slot, not from the middle like 9007s are designed. Shosource also has a good looking one for $45 I think.

So do you second Stephen's assessment of min. voltage on #86 relay post?

I got the wiring diagrams of all lighting systems from shorod. Man, that guy is prompt!

 

[SHOZ123]

Probably the picture is not for the correct plug ends. You could always ask the seller.

A relay should work on down to 10.5 volts has been my experience.

 

[SHOZ123]

And 18 ga wire is too small.

 

[98SF19]

So I still haven't resolved my headlight ordeal - just too darn much going on. The issue has taken a new dimension. Popped the hood last night and checked on some stuff, one of which was why my front side marker lights were dim to be barely visible, even at night. I thought I had put LEDs in there but they were the stock incan's, which may be a factor. Plugs were putting out 12.2 V +/- on both sides. If one of the two front side markers was dim, I'd say it was just the bulb, but both were very dim. I'm thinking it has something to do with either the low voltage on driver side headlight OR more likely IMO, the two yellow amber LED in parking light fixtures drawing lower current. Can anyone offer some expertise on this? On a side note, I did notice that when I jumped one of the plugs on accident, the parking light went to high intensity . Another oddity, possibly unrelated, is that on my instrument panel, both turn signals are lit when lights are on. When blinker is operating, they do indicate flashing with a higher intensity. I'm pretty sure this is due to LED parking lights and tail lights, possibly also involving my adjustable rate flasher, but if anybody wants to explain it, I'm all ears . . . eyes.