1980 720 lower rad. shroud came loose and severed wires to distributor module, coil etc.

[Datsdat]

Thought I'd hit a freakin IED but turned out to be just as unlikely. Now I have just the mangled remains of wires that formerly went to matchbook e.i. module, coil, temp. sender and choke heater and a few more I cannot identify. The cut wiring branches off the larger bundle that runs along the top of radiator and then shoots straight back to the distributor and carb. I count six severed wires and can't find a diagram that jives with the color coding. Engine is L20B, I need at least the color coding of the two wire T connector to the ign. module, plus wires that went to ignition coil, choke heater and temp sender. Diagrams found so far don't match. I know there was also a ground wire to the module that I need the color of. Any help would be forever appreciated, this truck had never stopped before in 40 years and I don't want to junk it just for a damn freak accident.  It would be easy to splice everything back together if I just knew the color coding. Thanks for any and all help. Please, all I need is someone with an 80 720 with L20 to look at those wires and let me know the color codes

[datzenmike]

It's just some wires and possibly this has also blown a fuse, nothing to worry about. It's totally fixable.

 

I'll look this up and some wiring diagrams in the morning for you. Again don't worry I had the same wires on my 521 wrap around the fan pulley and rip them off out in the woods and I fixed it and drove home.

[datzenmike]

To the back of the carburetor:

Blue/Red stripe becoming Blue for the auto choke heater

Brown becoming Red at carburetor for the idle cut solenoid

 

Yellow/Black for the water temperature sender on the thermostat housing

 

Distributor

Brown/Red to distributor module (matchbox)

White* power from ignition to matchbox module (and coil+ see below)

 

Coil

Black/Red to coil positive (-) terminal from module

White* to coil negative (+) terminal from ignition switch.

[Datsdat]

Cheers Mike, and thank you for the extremely helpful info. I need clarification on the single larger gauge white wire. If is a hot wire from the ignition switch, why would it not go to coil positive? I had a single white wire, same gauge attached to ignition positive which wasn't cut. I thought one would be ignition feed start and the other ignition feed run. What am I missing here in my logic? Could you please elaborate? Thanks much

[datzenmike]

On 1/28/2023 at 5:54 AM, datzenmike said:

To the back of the carburetor:

Blue/Red stripe becoming Blue for the auto choke heater

Brown becoming Red at carburetor for the idle cut solenoid

 

Yellow/Black for the water temperature sender on the thermostat housing

 

Distributor

Brown/Red to distributor module (matchbox)

White* power from ignition to matchbox module (and coil+ see below)

 

Coil

Black/Red to coil positive (-) terminal from module

White* to coil negative (+) terminal from ignition switch.

 

 

Wow I really got that wrong. Here is the corrected wiring. White powers the ignition module (matchbox) and also the + side of the coil. Check carefully I changed more than one thing.

[Datsdat]

 Hi Mike, I have a black and red wire that I can connect to the ignition module but before I do I checked it and with the ignition switch in on position and I'm reading around 5 volts at that wire. I peeled more insulation back and the black and red is spliced to a black and yellow. Is that normal or should I just fabricate a new wire direct from the coil negative to the module?

[datzenmike]

The Black/Red wire on the module should go to the coil negative terminal. It also goes to the tachometer so maybe... ?

The White wire should have 12 battery when in the ignition on position and also go to the coil Positive terminal.

 

What you are reading is some of the 12v on the positive terminal flowing through the coil resistance to the Black/Red wire on the negative terminal. To prove this disconnect the positive coil wire and it should stop. If it does this is normal and connect it back up.

 

[Datsdat]

Got engine running  but clutch goes to floor. Problem is all replacement slaves have bleeder screw below input line when mounted unlike the current slave. Why would this be, is the 80 720 different than other 720's or what the deuce is going on? Current slave is unmarked so I don't know where to find another. Slave is on passenger side and push rod faces rearward when mounted.

[datzenmike]

Bleeder should be on the end of the slave, not to the side, and above the hose.

 

What's wrong with the slave you have? What happens when you bleed it???

[Datsdat]

At present the pedal goes to floor without moving the release lever after bleeding all air out. I am replacing master and slave just to be sure but like I said, all pictures of replacement slaves with bleeder on the end show the bleeder screw at the bottom when mounted on right like my original standard Datsun 5 speed. It's like they are all meant to mounted on the driver side. The one currently on the truck has bleeder on top when mounted on passenger side but none for sale appear to match the one I have. I've looked at dozens of brands pictured.  They all would have the bleed screw at the bottom when mounted on the right side of the tranny. What's weird is that the 4WD slaves have bleed screw on top when mounted on  passenger side but would not clear the torsion bar.  I might end up having to rebuild the slave I have if I can't match it and that sucks.

[datzenmike]

All truck slaves have the bleeder in the end to clear the torsion bar.

 

Swap the bleeder and the flex hose around so bleeder is at top?

[Datsdat]

Thought about that already and the bleeder screw bore has a smooth tapered seat while the hydraulic line bore has a copper insert at bottom of bore. Went ahead and ordered a rebuild kit for my slave,