Hello people!!



Do I have a pain in the rear for you! I have an 86 F-150 XLT Lariat 302 auto, it runs great! Well, that is after I replaced the water pump, cleaned the radiator, and got new upper and lower hoses. It runs great! Well, other then the battery dies every night.So, this is where I am right now, I found out that I have a .5 amp draw from my battery at ALL times. I've done all the simple stuff, check the door light switch, radio, all that stuff. I've pulled all the fuses and the draw is still there, the alternator is disconnected. I've found the wire causing me all this grief, it's the 12V source for the ECM. I know that the computer draws some current as to keep the memory inside of it alive, but it should be in the mA range. I've been looking for the relays for the ECM and the fuel pump. I think I found the horn relay, it was attached to the side of some smaller computer which is attached to the ECM, I also found something that has three pins, I've never heard of a three pin relay, so, yeah. I know that the ford four pin relays have a tendency to go out, so I would like to replace them with some good ones, I have some bosch relays that will work nicely. So, Oh masta's of fords, what ails my beautiful Turd Nugget?

 

So, you're saying 0.5A draw exists with both the alternator AND
all the fuses removed at the same time?

 

Yes, so what that told me is that where ever this draw is, it's before the fuse box. This is just insane.

 

Hmm, I think I might of found my little migraine! The horn relay is a 3 pin relay, first time I've ever heard of one, but this is a ford. I just got back from Checker and they brought out the same relay and I just so happened to bring my DMM. I look thru the big book of switches/relays that they have there and I found the internal diagram of it.

Yea it's blurry, the three pins are 1, 3, and 5. I hope I labeled them correctly. Stoopid me I forgot to write down which pin is which. BUT, I ohmed out 5 and 1 on the new relay and got like 830 mega ohms, which is close enough to be an open. On mine I did the same thing and got 236 kilo ohms. For those who aren't really up to date with metrics, 830,000,000 for the new one and 236,000 on the new one. I think that it's letting enough current thru to cause the .5A draw, but not beep the horn. So when it cools off outside, it's 92 right now, I'll put in a new bosch relay in its place. I hope this works.

 

I don't have a horn relay so I can't test mine to compare but your theory sounds plausible.

You should fill out the rest of your profile so people can see where you are.......

-ct

 

Well, I believe I'm a human. I've been wrong before though!!! Bullhead City AZ, across the river from Laughlin NV.

 

830 mega ohms.you had your fingers on the test leads didn't you.if it's open it should be 0. 830 sounds like the resistance through your body.when i test mine i always make sure none of my fingers are touching,as this will cause a false reading.

 

Heh...heh...heh... ahh.... Got me there, I just re did it, and got it open. I guess I had my finger touching something. I was kinda confused as to why the numbers were fluctuating...... I still would like to replace the relays, I have the horn relay and the fuel pump relay. Would you happen to know where the ECM relay might be?


My chiltons shows the horn relay having 4 wires, I only saw 3. One hot for the horns and cruise control, one to the horns and the other two for the cruise. Why tie in the horn and cruise? Is it just ford being ford?

 

my haynes shows nothing. i have to get shop manuals.lol

 

PLEASE DO!!! As I've said, the truck runs fine. I just can't park it over night or for a length of time because of this short. This is the only thing that's really hanging me up. After this I want to just clean the engine bay up. My oil pan is leaking some, but the chiltons says I have to unbolt the engine mounts and jack it up. To me, that sounds like I won't park it on my driveway. The valve cover also leaks, but neither of them are really that bad. I just want this thing to run and me not worry about if there's an electrical outlet within reach of where I park it.

 

Franklin is our electrical guru.he probably has a diagram.

 

Well, I guess I have to wait for him then. One thing that I want to do is make all my gauges flat black and color the number/lines. The tach I got recently I used to test on. I grabed a sharpie and 2 highliters and this is the result.
I like it, it looks like something now. I have some flat black paint, but it's just not flat enough. 0-10 are slightly yellow, just doesn't show up well.

 

So, does ANYONE have a wiring diagram that's more specific? I would really like to get this truck up and running. Then I can move and find a job where I wouldn't mind working in the elements.

 

Lloyds Auto Liturature available for 1986, Fordtruck, Wiring Diagrams

 

You can try autozone.com they have all kinds of wiring diagrams you just have to know how to decipher them.