123/ignition and automatic transmission

[madkaw]

Hey guys , I’m installing the 123 ignition on a customers car and he has automatic transmission . This is a 2/72 . I’ve been looking at schematics and I’m trying to educate myself on inhibitor switch’s and the rest of the workings of the auto trans .

I don’t have a FSM and I’m using a Haynes manual and it doesn’t cover the electrical side of the auto trans . I just ordered a FSM for the chassis on S-30 and hope that help.

My current concern is Red/black wire that splits to the two blacks - going to coil - and distributor . I would think that these are part of the inhibitor circuit so I need to tie these into the circuit with the 123 ? Are these grounds once all the requirements are met in the inhibitor circuit ? Trying to figure what the thermo relay does ? 

Every black wire I measure shows no ground . Makes me wonder if that’s an issue. 
 

One last issue . It seems I have a battery drain . When I hook up my battery cables the voltage regulator clicks like a relay - is that normal . After charging my battery i checked voltage and lost .5 volt pretty quickly . The voltage regulator was warm 

 

[SteveJ]

A bad VR can drain the battery. That was one of my first Z car lessons over 28 years ago.

For the inhibitor switch, look at the 73 wiring diagram for Automatic Transmission.

Here's how the wiring works:

The reverse switch AND the inhibitor switch are fed by a red wire. Each device is wired to a red/black wire that goes back to the reverse lights. I think this is a red herring (no pun intended).

Anyway, the inhibitor switch should also have two black/yellow wires going to it. In other words, the inhibitor switch interrupts the solenoid power. No need to tie the 123 to anything but the black/white that goes to coil positive. There should be another wire from the 123 to coil negative to ground the negative when the distributor wants to fire. The stock wiring has a black wire that goes from coil negative to the points for the points to ground when it's time to fire. Then if there's yet another wire for ground, it could be grounded to the block for all you're concerned. Post the 123 wiring diagram to confirm.

As for the green/white and other black/white at the ballast resistor, you can probably jumper those together.

[Reptoid Overlords]

On a different topic but somewhat related, be mindful of the slop in the 123 distributor to oil pump shaft\tang.  perhaps you've dealt with these already, but in case you haven't, you'll need to shim it up with something to prevent play.  It'll cause the car to run poorly.

Apologies if I'm yammering on about something you already know.    

[madkaw]

35 minutes ago, Reptoid Overlords said:

On a different topic but somewhat related, be mindful of the slop in the 123 distributor to oil pump shaft\tang.  perhaps you've dealt with these already, but in case you haven't, you'll need to shim it up with something to prevent play.  It'll cause the car to run poorly.

Apologies if I'm yammering on about something you already know.    

I thought the fit was quite snug - but I’ll look at it again 

Edited March 28, 2022 by madkaw

[madkaw]

1 hour ago, SteveJ said:

A bad VR can drain the battery. That was one of my first Z car lessons over 28 years ago.

For the inhibitor switch, look at the 73 wiring diagram for Automatic Transmission.

Here's how the wiring works:

The reverse switch AND the inhibitor switch are fed by a red wire. Each device is wired to a red/black wire that goes back to the reverse lights. I think this is a red herring (no pun intended).

Anyway, the inhibitor switch should also have two black/yellow wires going to it. In other words, the inhibitor switch interrupts the solenoid power. No need to tie the 123 to anything but the black/white that goes to coil positive. There should be another wire from the 123 to coil negative to ground the negative when the distributor wants to fire. The stock wiring has a black wire that goes from coil negative to the points for the points to ground when it's time to fire. Then if there's yet another wire for ground, it could be grounded to the block for all you're concerned. Post the 123 wiring diagram to confirm.

As for the green/white and other black/white at the ballast resistor, you can probably jumper those together.

There’s a thermal relay that the RB wires runs thru . There’s also a thermal switch in there somewhere . Not sure what their function is . 
So you think I don’t need to connect the RB to the coil -   like in the original wiring ? 

[SteveJ]

6 minutes ago, madkaw said:

There’s a thermal relay that the RB wires runs thru . There’s also a thermal switch in there somewhere . Not sure what their function is . 
So you think I don’t need to connect the RB to the coil -   like in the original wiring ? 

I misunderstood your question. The wiring diagram shows the black wire going to the negative of the coil. At the distributor, it meets up with the RB wire. (It could be RB from coil negative to the relay for all I know.) The coil positive should have the BW wire as I mentioned earlier. The RB wire goes to the relay that controls the advance for the dual point distributor and when the contact is closed, it goes to the black wire that goes to the other set of points. Pages EC-11 and EC-12 describe the system. When the car is cold, the temp sensing switch contacts are closed. The relay coil is energized, and the RB wire is connected to the black wire that goes to the advanced timing points. When the car warms up, the switch opens and the relay is de-energized. The contacts open at the relay, and the RB wire is open, leaving the retarded points in the ignition circuit. 

The 123 is not dual point to my knowledge, so you don't even have to worry about that wiring that I just explained. Without knowing which 123 model you're installing, I just grabbed one of the drawings. I can revise my explanation with more information.

 The BW wire goes to the coil as normal. No other stock wires go near the coil. (Jumper the GW and BW at the ballast as I mentioned before.) The black wire from the 123 goes to coil negative. The blue wire gets grounded. If the wire is short, you can ground it to the distributor mount.

[madkaw]

Awesome @SteveJ explanation . More stuff to delete !

The diagram you picked is correct for my 123. The blue wire is about two feet long . I was hoping one of these wires I don’t need anymore was a good chassis ground . I’d like to get as close to the battery as possible . I figure a good ground is essential . Too bad my harness is all taped up and pretty .

I just didn’t want to take anything out that broke the circuit of the inhibitor or somehow alter the operation on the automatic .

[SteveJ]

The lowest resistance ground is probably at the distributor mount. See my video linked below. You have the large gauge cable firmly attached to the starter. The starter is firmly attached to the bell housing that is firmly attached to the engine. Unless you have a large gauge cable firmly bolted to the chassis, the engine will have less resistance. 

I just went down to my garage to verify. From battery negative to the distributor mounting bolt, the meter read 00.0. From battery negative to the shock tower or bolt for the coil, the meter read 00.1. The 00.0 tells me resistance is probably less than 0.05 ohm. (I'm not sure at what point it might round up.) Either grounding place (engine or chassis) should work as long as the surface at all the grounding points is clean and not corroded.

 

[madkaw]

11 minutes ago, SteveJ said:

The lowest resistance ground is probably at the distributor mount. See my video linked below. You have the large gauge cable firmly attached to the starter. The starter is firmly attached to the bell housing that is firmly attached to the engine. Unless you have a large gauge cable firmly bolted to the chassis, the engine will have less resistance. 

I just went down to my garage to verify. From battery negative to the distributor mounting bolt, the meter read 00.0. From battery negative to the shock tower or bolt for the coil, the meter read 00.1. The 00.0 tells me resistance is probably less than 0.05 ohm. (I'm not sure at what point it might round up.) Either grounding place (engine or chassis) should work as long as the surface at all the grounding points is clean and not corroded.

 

Thanks again . I know the block is a great ground , so I am over thinking things . I’ve cleaned all the grounds everywhere on the chassis .

[SteveJ]

1 minute ago, madkaw said:

Thanks again . I know the block is a great ground , so I am over thinking things . I’ve cleaned all the grounds everywhere on the chassis .

You're routing the black and red wires from the 123 over to the coil. You might as well route the blue one there, too, and ground it on the coil mounting bolt.

[Reptoid Overlords]

I know it was not a problem you were experiencing, but just to clarify for future reference, the slop I was having was due to the shaft/tang currently installed in my car being slightly thinner than it's supposed to be.

A spare shaft proved to have no slop.