Moar lower, some new fixes, and the answers to life's questions

[Smyrna720]

Alright, alright, so I'm back. Done a little of this and a little of that, been halfway around the world and back. It's summer time again. Life is good.

 

So, since I promised moar lower, Here it is before. 3" block in back, torsion bars in front, 225/60R16 tires on 99-03 silverado wheels.

 

 

Here, Middle leaf removed, bars cranked down in front, 205/55R16 tires

 

 

 

 

 

 

 

 

 

And just to prove it's a daily...

 

 

[Smyrna720]

So, I was having some weird headlight issues and contacted Wayno. Here is our convo.

 

 

 

 

Sent 07 January 2014 - 08:09 PM

I've been searching around and it seems you know the 720 headlight harness pretty well. My problem is this. First, the passenger side low beam headlight is dim. It's only getting 9 volts. I need to know where the two spice together in the harness in the truck. Second, my bright headlights are getting 2 volts when the lows are on. If I unplug the passenger high, the highs go off. If I unplug the driver high, the passenger stays on. I'm having a hard time making heads or tails out of the wiring schematic I pulled off AllData. If you have any good ideas, let me know. If you're feeling froggy, give me a call at . I should be tinkering with this for another hour or so. It's 8:10 central here. TIA.

Josh

1985 Nissan 720, made right here in Smyrna TN

 

 

Sent 07 January 2014 - 08:29 PM

Hey there Josh, I hate wiring, I really am not that good at it, when things go bad, and I cannot figure it out, I just use another wiring harness.

 

OK, do you have any aftermarket gauges, fog lights, anything that you had a reason to tie into the headlight wiring harness?

Did you add any grounds for any reason?

To have gauge lights at night and such things?

You put in a radio lately?

Are your headlights the stock type, or you trying to use something else?

•  

wayno

Sent 07 January 2014 - 08:30 PM

This is very important, have you checked your fusible links? 

Have you replaced your headlight fuses?

 

Smyrna720

Sent 07 January 2014 - 08:43 PM

wayno, on 07 Jan 2014 - 9:29 PM, said:

 

Hey there Josh, I hate wiring, I really am not that good at it, when things go bad, and I cannot figure it out, I just use another wiring harness.

 

OK, do you have any aftermarket gauges, fog lights, anything that you had a reason to tie into the headlight wiring harness?

Did you add any grounds for any reason?

To have gauge lights at night and such things?

You put in a radio lately?

Are your headlights the stock type, or you trying to use something else?

Stock Guages in the console. Wired using factory harness.

 

Did not add any grounds.

 

All other lights in the truck work correctly.

 

Aftermarket radio but it's been there for some time. I wired it in using the factory harness. I unpluged it and nothing changed.

 

Stock sylvania sealed beams across the board.

 

 

I am usually very good with wiring as it's something I troubleshoot every day at my shop. I just can't figure out how this truck switches and how it works. Where does this thing ground at? Wierd.

 

I need to know what voltages I'm supposed to have and where they're supposed to be. Case in point, with the lights on low, I unplug a high beam. I have 12 volts on one side and 9 on the other. WTF?

 

Thanks for your help.

 

•  

Smyrna720

Advanced Member

•  

Sent 07 January 2014 - 08:44 PM

wayno, on 07 Jan 2014 - 9:30 PM, said:

 

This is very important, have you checked your fusible links? 

Have you replaced your headlight fuses?

Yes

 

No.

 

I did however check voltage AT the fuse, across the fuse, and I have 12v.

•  

Smyrna720

Sent 07 January 2014 - 09:05 PM

I found this. Correct me if I'm wrong.

 

Red is grounded from the headlight relay 87A (normally closed) terminal - all 4 headlights are grounded by the red wire.
Red/yellow stripe (relay 87 terminal normally open) controls the low beam by grounding this wire and disconnecting the red.
Red/Blue wire is left side headlight power supply from the headlight switch.
Red/Black wire is right side headlight power supply from the headlight switch.
Red/Blue and Red/Black stay 12volts all the time when the headlights are on and the hi/lo switch is done with the grounds through the headlight relay.
 

 

wayno

Sent 07 January 2014 - 09:20 PM

Did you unplug the fusible links from there plugs before testing them, what I mean is did you isolate them from the rest of the wiring?

The 720 harness is a weird animal, it does shit I don't understand, it will back feed threw wires and show 12 volts, but it is not coming from the battery, the power is actually coming from the fuse block, when the fusible link is supposed to be supplying the power.

 

Don't look at your headlight fuses, just replace them(2 closest to the firewall I believe), I have had one look good before, but it was bad.

 

 

wayno

Sent 07 January 2014 - 09:26 PM

Smyrna720, on 07 Jan 2014 - 10:05 PM, said:

 

I found this. Correct me if I'm wrong.

 

Red is grounded from the headlight relay 87A (normally closed) terminal - all 4 headlights are grounded by the red wire.
Red/yellow stripe (relay 87 terminal normally open) controls the low beam by grounding this wire and disconnecting the red.
Red/Blue wire is left side headlight power supply from the headlight switch.
Red/Black wire is right side headlight power supply from the headlight switch.
Red/Blue and Red/Black stay 12volts all the time when the headlights are on and the hi/lo switch is done with the grounds through the headlight relay.
 

Looks like you know more than I do, have you tried another relay?

I had one go bad in my 520 project, it screwed everything up, I think I spent most the day before I figured that one out.

 

 

Smyrna720

Sent 07 January 2014 - 10:38 PM

wayno, on 07 Jan 2014 - 10:26 PM, said:

 

 

Smyrna720, on 07 Jan 2014 - 10:05 PM, said:

 

I found this. Correct me if I'm wrong.

 

Red is grounded from the headlight relay 87A (normally closed) terminal - all 4 headlights are grounded by the red wire.
Red/yellow stripe (relay 87 terminal normally open) controls the low beam by grounding this wire and disconnecting the red.
Red/Blue wire is left side headlight power supply from the headlight switch.
Red/Black wire is right side headlight power supply from the headlight switch.
Red/Blue and Red/Black stay 12volts all the time when the headlights are on and the hi/lo switch is done with the grounds through the headlight relay.
 

Looks like you know more than I do, have you tried another relay?

I had one go bad in my 520 project, it screwed everything up, I think I spent most the day before I figured that one out.

 

 

Fixed it. Ok, here's what I did. That wiring description above is for the back of headlight switch. I backprobed the wire that supplies power for the driver side headlights. 12 volts. I then backprobed the Red/Black wire that supplies power to the passenger side headlights.... 6 volts. The contacts on the switch were crappy. I took a file, cleaned them up and now everything is right as rain. That would also explain why this was a cumulitive effect I didn't notice until now. On a side note, I actually did this 2 years ago when I redid the interior of my truck. I guess I know how long it takes for those contacts to get shitty again.

 

As for a relay, I had another on the bench and swapped it out to no effect. Also, the fusible links all tested good when doing my voltage drop test across them with a load on the system. As far as the fuse block feeding voltage when it's supposed to come from the fusible link... you're right. That's nuts. I had the same nightmare trying to figure out the wiring for something else. I think it was the blower motor.

 

All that said, I'm still not exactly sure how these damn headlights operate.

 

Thanks for all your help. I'll try to make a post on this sometime in the near future.

 

Josh

 

 

wayno

Sent 07 January 2014 - 10:41 PM

I am happy you figured it out.  :)

 

 

 

wayno

Sent 07 January 2014 - 11:00 PM

What you have to keep in mind is that the headlight circuit has no grounds on the headlight side of the relay, and the gauge lights have no ground on the dash light side of the illumination unit(the knob in the dash just over the e-brake handle), if you put a ground in between these two points on either system, everything gets screwed up.

The reason I know a little bit about this 720 wiring harness system is because I use these wiring harnesses in my 521/520 builds, but I also transfer as much of the 720 as I can, like I use the 720 steering column complete with the combination switch, the only thing I have to integrate the 720 harness into is the 521 is the instrument cluster, and that is how I know about ground issues, you see the 521 instrument cluster uses grounds for the dash lights, and more importantly, the brights indicator is a ground in the 521 instrument cluster, which screwed the whole system up, it made the brights headlights all come on barely all the time, and when you hit the brights, it did something else that I cannot remember now, even datzenmike had issues with that in his 620 4X4, but he never figured it out, he just lived without the brights indicator light in the dash. 

Thing are good for you now, and each time something happens, you will figure it out a little faster, and then one day everyone will be asking you how to fix it.  :lol:

I know the voices are not real, but they have some really good ideas.
 

 

 

 

The moral of the story is check the easy stuff first. Like the switches.Duh.

[Smyrna720]

Lastly, shortly after lowering it more, the speedo quit working. Fix for that upcoming. It also needs brakes. I'll post pics of that too.

[millican]

Cool.

Your truck seems to be lacking the usual rust and dents. Want a few of mine?

(in other words, it looks nice)

[datzenmike]

Measure the rear spring arch and take those removed leaves into a spring shop and have then de-arched to match. Put them back on. It won't change the new height but will however resist suspension travel over bumps and dips reducing the chance of bottoming out. It will also corner better.

[Smyrna720]

Cool.

Your truck seems to be lacking the usual rust and dents. Want a few of mine?

(in other words, it looks nice)

 

 

Thanks man. It's got a little rust in the bed and a bunch in the cab floor, but overall it's pretty solid.

 

 

Measure the rear spring arch and take those removed leaves into a spring shop and have then de-arched to match. Put them back on. It won't change the new height but will however resist suspension travel over bumps and dips reducing the chance of bottoming out. It will also corner better.

Truthfully this is just a temporary thing. I'm either going to get some leaf packs off a 4wd, OR get an explorer 8.8 rearend and 4 link it. Probably number 2. I would really like to 5lug swap it and put the Chevy LT1 in my garage in it. Just waiting on time to do it.