Wiring harness help

[None_zero]

I decided to make a new thread since my issue has changed multiple times in the course of the other one. The situation is this, the wiring harness in my 84 720 with z20 engine manual trans 2 wheel, has been cut in half just behind the gauge cluster. I have reattached everything and almost everything works, however. My headlight switch is scrambled so that brights = on and you toggle between bright and dim by switching from parking lights to headlights I have no parking activation. And the choke seems to be wired to the clutch as the engine idles very low even with fuel pedal fully depressed and then revs when clutch is depressed. If anyone can give me a clue as to what I should swap to where that would be fantastic. Thanks

Edited March 7, 2022 by None_zero

[paradime]

Often harnesses have multiple wires with the same or very similar color combination so it's easy to get them mixed up. Did you work from a manual diagram to identify each wire and trace it out to it's destinations? if not you should get the Haynes Vehicle Repair Manual 72030

[datzenmike]

I have a Haynes 720 manual but the cover is so worn I can't confirm that it's the same as above, however it only has the 1980 and the '81-'82 wiring harness diagrams. The '83 and up is simply an added abbreviated supplement and a single wiring  block diagram for convenience and the indicated connections are not inclusive just lines indicating connections nor the number of wires, and naturally no color code. It also is expected to cover from '83-'86.5 and every year and every model (gas and diesel) were different.

 

More expensive is the FSM factory service manual produced by Nissan and about 3 times as thick and exclusive to the '84 model year. Although there is no single wiring diagram (too complicated to fit or to read on a double page) there is a diagram for every electrical circuit showing every connector, every wire and color from battery to the final ground. It's the bible on that particular year of the 720. It's publication number for  1984 is SM4E 0720 U1 (first revision) Usually from $20-$80 e-Bay

 

 

[Thomas Perkins]

I have the Haynes.Is for All Nissan/Datsun pickups and Pathfinder 1980-1991 and the 85 Nissan FSM Service Manual.I can send pictures.

Edited March 8, 2022 by Thomas Perkins

[datzenmike]

Haynes is poor. Has to cover 6 1/2 years of 720 and 5 1/2 years of D21 Hardbody in a 1/2" thick manual. Half the book is not even applicable. Good luck with that if you have an '84. For weekend dilettantes who need to look up spark plug gap measurements.

 

FSM is at least twice as thick, and only covers the year of your truck, but thoroughly. For serious owners who like to maintain their trucks or just want to  keep their mechanic honest.

[None_zero]

Fsm huh ok I'll see if I can find one 

[None_zero]

What should I expect to pay for something like that because the first one I found is $75 which seems high unless the book is gonna teach me to fly and supercede the need for a truck 

[bilzbobaggins]

75 to unfuck your self seems reasonable.  I pay more that that to get fucked.

 

But, search around, there could be a better deal.

[datzenmike]

On 3/8/2022 at 6:59 AM, datzenmike said:

 It's publication number for  1984 is SM4E 0720 U1 (first revision) Usually from $20-$80 e-Bay

 

 

 

Ask what does a mechanic charge per hour. Knowledge is power. Power and money are interchangeable.

[Thomas Perkins]

I bought my 85 Nissan Service manual from the dealer years ago for 75 bucks,Brand new.Ebay has a used one for 94.99, and 128.16,I like both of my books.Everyone can't get a FSM book,so a Haynes is better than nothing.I bought a speedometer from a guy on 720 World and he sent me two of them and the wire harness.I never used them.I still have them.I would like to take my speedo out and put in a new light.The one by the left upper side is burnt out.https://www.ebay.com/itm/185307124524?_trkparms=ispr%3D1&hash=item2b252a532c:g:fgQAAOSw2CtiE8Yh&amdata=enc%3AAQAGAAACoPYe5NmHp%2B2JMhMi7yxGiTJkPrKr5t53CooMSQt2orsS7UXID%2BRPOSNsnm8kYPghtOQNvbjDxl2jahflQDBO0dmUI%2BJpZeJbn9dsXFDCd46etHn7KPu9kPdebS%2BZP4UQxkS0bau7Ws6lPt6rzPG9Rh1Uf1dbJb1DYbQw0X5b5OELy8rLwOyPcfuOL60wo2lJUdKyR05Jm6JnBYilJEoeXB5K%2FVF8Ydp5F5d%2B6AYSCLDzJ002fiOhOlqwpoZ7WsOAefqwtInOt8RPf8rkwxILmJcj7FjbrjuA4uBV91bMgwFZSE4Y32IOgrFf1jJUPyXLtrMrTfY%2Bo9%2FT%2FaehLG7oHtfrpdMyLTN4acHYWBae1fpUPMMxld96vn5q9LyjYcOyKxrsxbfrFxTYoSgRUwtwSfedjbWibr5omuQtlU7364RK3iJEZDXdiNncsxgSGU4RSTEHGjQVX882HyzRcYMXxR6%2FM99pys9dAXE%2FVLYzLG9OOT0W9n%2F3Z16Q%2FL1D9utU2rytv%2B2TDd73K0nSldUvsRa9WxkIAVRZHYH6n1l6Nh0vBLhf1lLp4rF3BHJhi1E95xBVNeVpq3qHt1tjqi3Na%2BTIdW9BXCl%2FMuYn84NL3dhCpNY1p%2FAuFVex9B5hrHWyXqNJ4d8vssBodVtCMSngCiXwoVVTz53dr7EZh08BqcE%2FDc9BXhfVrDsyMTiplV6UVRGdR51CRKv7PyCXG1IogGdW5as3WJDLyu8DbF5ac0rtfTCumi%2BKYWsFIz1ZawnzbToznf5vkNqn8%2FtrLrWHwx8Gzmcp4gLCiBt3%2FkbkPm5Uer7MkIoNrNSbz5TEu75Ph9vgR0IcSPb0tHKpr9h%2Ft2mdlbVn6FGDCzyhqzUkHPZzHZ%2FA0KKf%2BSbq83fYoBusIw%3D%3D|clp%3A2334524|tkp%3ABFBMjv7y3-5f

Edited March 10, 2022 by Thomas Perkins

[Stoffregen Motorsports]

On 3/8/2022 at 12:07 AM, paradime said:

Often harnesses have multiple wires with the same or very similar color combination so it's easy to get them mixed up. Did you work from a manual diagram to identify each wire and trace it out to it's destinations? if not you should get the Haynes Vehicle Repair Manual 72030

I have found that even when the colors are the same, ie- red with a blue tracer, there will be another color code on the wire, like a silver dash, or two silver dashes, much like a resistor or diode. I'm speaking in general terms though, not Datsun/Nissan specific.

[wayno]

Personally, I would go back to the repaired wires and find which ones are wrong, it is just easier that re-inventing a wiring harness.

[None_zero]

So I've made some progress and maybe a little light has appeared at the end of this tunnel. I drove it down the road today and aside from being a bit light on horse power and needing to keep my foot on the clutch just a little. It did ok. Seems like now I just need to adjust the choke, and I'm assuming, the clutch switch is either "normally open" or "normally closed" and somehow I've reversed it... Does that sound right ?

[datzenmike]

This is messed up. Like putting a jig saw together blind.

 

Lack of power? Check that both coils are firing. If one coil not working take a look st your distributor wiring...

 

 

See the separate wire on the right with it's own plastic connector? Unplug it and that should get them both working and get your power back

[None_zero]

Unplug the heater plate ? Your saying?

[None_zero]

Distributor wires like the spark plug wires and coil wires?

[None_zero]

Oh I'm dumb sorry that is the distributor and the wires you're talking about in the pic 

[None_zero]

I don't understand though I've got a black ground going to the saucer shaped thing and the rest is hardwired into a terminal that goes B/W to Br , R to W/L and L to R

Edited March 15, 2022 by None_zero

[datzenmike]

3 hours ago, datzenmike said:

 

 

 

See the separate wire on the right with it's own plastic connector? Unplug it and that should get them both working and get your power back

 

Let me repeat...

See the separate wire on the right with it's own plastic connector? Unplug it and that should get them both working and get your power back

 

[None_zero]

I don't seem to have that seperate plastic plug or if I do it's already unplugged 

[None_zero]

,

[None_zero]

Is that it there? 

[None_zero]

Holy shirt man you're a genius! That seems to have sorted it out. So what is that plug for?

[datzenmike]

It's to tell the distributor to switch from dual plugs to single plug operation. This is to reduce engine noise under severe load. A vacuum witch senses low manifold vacuum from heavy throttle and grounds that white wire. Ground on it tells the ignition to turn the exhaust side plugs off.

[None_zero]

Ok so I'm grounding that wire somehow and it's telling the distributor to cut the exhaust plugs so I can't get torque to the wheels at low speeds?

 

As an aside I checked the timing and it was at 10° retarded but it was jumping down an extra 10° every so often (assuming that I'm remembering correctly that each line represents 10° difference with the middle line being zero) is that right ?