I have been tracing down electrical problems, and need some help on this one.

Keep in mind my 70 442 was completely tore down and I am just now getting it on the road and I never drove it before. I bought it as a roller.

When plugging in the TH400 kickdown switch. The car will not shut off. Turn to off, pull the key out, and the motor continues to purr like a kitten. Pull the guage fuse in the lower right corner of the fuse panel and engine stops.

Since this is a two prong switch. Should the pink wire go to the to the terminal toward the interior and the orange wire go to the terminal toward the cowl? Or vice-versa? If the plug was put on the wrong way would this cause power to feed back to the coil?

Thanks.

 

The switch is simply an on-off switch. It doesn't matter which way the connector goes. More importantly, there is no connection between the kickdown circuit and the ignition circuit in the factory wiring. The pink wire is the power feed from the GAUGES/TRANS fuse. It only runs from the fuse box to the kickdown switch and the instrument panel to feed the gauges. The orange wire runs from the switch connector to the firewall connector. And even more importantly, that kickdown switch is open unless the pedal is at W.O.T., so even with the connector plugged in, the switch would still be open.

Has this car had an HEI added? If so, where was power taken from? Is it possible that there is a short in the firewall connector? There is no normal way for the ignition circuit to be connected to the kickdown circuit.

 

Joe,

All that you say is true, ....or so I thought.

For clarification, when I look at the CSM wiring schematic, it looks to me like the pink wire comes from the ignition and branches: one side going through a plug to the coil (wire from plug to coil is noted as a resistance wire); the other side going to the fuse box and through the fuse to the kickdown switch then on to the gauges. So in theory isn’t the pink wire part of the ignition circuit? Or at least could back feed power to the coil?


As always you instincts are somewhat correct. Other variables
1) Yes I have a MSD box and distributor.
2) I have an electric choke on an aftermarket carb. (No, I do not know where either of those items are getting power from as the wiring is all taped up. I have a call into the shop today to see what they did. When I picked up the car, they had never hooked up the kickdown switch.)
3) Switched from idiot lights to Rallye gauges (Wires appears to have been changed correctly to the gauges).
4) Fuel guage only reads 1/2 of what is in tank. ( I suspect this is a separate issue and is related to a bad ground, just have not got that looked at yet. Disconnect the sending wire in the trunk then ground the wire: gauge fluctuates from full to empty as it should.) I only mention this here as it is part of the circuit.

My intent is to work backward for the kickdown switch. I suspect it will ultimately lead back to the two power wires added to the MSD box or electric choke.

However, I am having trouble understanding why plugging in the kickdown switch manifest the problem.

 

The kickdown switch is on the gauges fuse I believe. When you pull that fuse, you remove power from the charge light. Where the root of your problem is

there is just enough current thru the charge light to keep the MSD powered with the key off. You can test the theory by replace the fuse, and unplugging the alternator. If the key operates correctly, you need to install a diode in-line with the charge lamp. The process is outlined in the MSD instructions

 

Yes, the pink wire is fed from the ignition switch, so all power comes from there. When you turn off the ignition switch, there is no power to either the coil or to the kickdown switch with the stock wiring. I have no idea what any owner additions have done to the circuit, but obviously something is backfeeding the power with the key off. Plugging the connector into the kickdown switch doesn't change the circuit at all, unless there is a short somewhere that is making contact when you flex that pigtail into position.

 

I would work from the coil+ terminal backwards and see where that wire/s are connected and go from there.

 

https://pitstopusa.com/p-4155-msd-ignition-tech.html

 

You said you have a MSD Box. Do you remember installing or has a "Diode" connected between the wires of the alternator and voltage regulator? The Diode is directional so it connects only one way.

 

Thanks for the information about the diode. I apologize for the delayed response bu we were out of town. I think I found it in the MSD box. Is this it?



My understanding is that this is directional, but I do not see any markings as to which way it goes. Is there a way to test it?

As for the rest of my system:
1), My 442 came with an internal regular alternator, and I upgraded it to a more modern alternator from a mid -80s custom cruiser.
2) My wiring is basically as below with the heavy red positive for the MSD box going to the horn relay, the negative grounded to the core support, and the red tied to the ignition (I still have not tracked its source yet.)



I will work with the Diode this week; however, I still do not understand why this only happens when the kickdown is plugged in.

Thanks again.

 

The silver side of the diode is the positive side.

 

On the Diode, there's a stripe, look at the MSD manual and it will tell you which way to face it.

 

Or, whatever way will allow the charge light to come on with the key on, engine off

 

I wired in the diode about a week ago, and this seems to have resolved this problem. I will note that the interior shop noted the run on with the kickdown unplugged. This is the first time
it did that. I quess the randomness of the electrical current, as the run on did not happen all the time, made my assumptions wrong on that part. I ended up taking a single plug wire from and old wiring harness, Removed the male terminal from the two prong alternator plug and placed it in the single plug. On the female side of the single plug I attached the diode to the wire, then on the opposite end of the diode, i attached the former male terminal of the single plug. I took the former single male terminal and placed it into the alternator plug. This way I did not need to cut my main wiring harness. It still needs cleaned up, but
here is a pic.


Thanks for the help.