Diagnosing an electrical problem at battery on 67 rt

[1carlover]

Yesterday I posted about direct ground sparking at negative battery post and meltdown of the fusible link at the solenoid. This is on a car with all new components under the hood and absolutely no problem 2 days ago when I could crank over the starter. Yesterday I replaced the fusible link and checked all connections but the problem didn't go away. I'm hoping someone can help shed a little more light on the subject. Today I tried removing wires from the solenoid and hooking up the battery to see what would happen. Only after I disconnected the fusible link from the solenoid there was no short or sparking at the battery. What would that condition indicate?

 

[super-bee_ski]

I need to look at wiring diagram.

 

[1carlover]

I think I understand the basics of the Mopar electrical system of that year. What I don't understand is why this problem occurred in the first place since everything is new. I haven't even fired the motor yet on this resto project and wont be able to until I figure this out. My understanding is that the fusible link energizes the ignition system from the key side of the ignition system as well as protect it from meltdown. My problem occurred at the battery side with the key off. I have also checked for melted wires or positive cable at the starter shorting out. I cant hook the battery up without frying the fusible link again. Any technical input would be greatly appreciated.

 

[nm9stheham]

Your test shows that the starter relay is not internally shorted and nothing else.

The fusible link powers pretty much everthing in the car, not just the ignition system; some is via the ignition switch but not all, some goes via the fuse blcok. If it melted, then you have enough current draw somewhere to be a serious issue. If you cannot spot an obvious problem with wires chafes or melted, then you will have disconnect a number of connections to see if this goes away; if so, then reconnect 1 at a time and recheck to see if the sparking comes back. If it does not go away with all connectors disconnected, then it is in the main harness in the dash, the ammeter, in the firewall connectors or inside the fuse block.

Do the following:
Make up a jumper with an inline automotive type blade fuse holder to connect between the starter relay big terminal and the fusble link and use a 20 amp fuse in it (not a slow blow type). This will be your temp fuse to protect things while you run this down. Then:
Start by disconnecting:
1) Connector to ignition switch
2) Connector to clock
3) Main wire to the alternator
4) Connector to the headlight switch
5) All fuses in the car's fuse block

This leaves only the ammeter and main power feeds in the harness connected to the fusible link. Connect the fusible link and your temp fuse and see if the temp fuse blows. If not, then reconnect the above one at a time and find which blows the temp fuse. The we can go from there.

You are 100% right to not go any further 'til this is fixed. I will be sending you a PM. And don't leave the balde fuse in the system; the fuse holder will not stand up to long term use with the high currents that will flow through it.

 

[1carlover]

Thanks for posting. I really appreciate your input and will put your ideas into action tomorrow. I just reinstalled the dash and heater box not too long ago with a very good used wiring harness and expected to pull the dash cluster out to install a new circuit board. I know the clock is not connected since it is still in my old dash and on my list of things to do. Everything else is connected correctly so it will be interesting to see what I find. I'll let you know. Thanks, Carl

 

[1carlover]

Hi Mark,
I wanted to give you an update on the electrical problem in the 67 RT that you were coaching me on. As usual been busy with other things but I think I have found the problem and have gained a much better understanding on how the electrical system works on this car. The first thing I discovered is that the wiper motor plug was not wired correctly by the person who restored my variable speed wiper motor. I finally got the wires in the right order and power to the wiper motor. To refresh, the problem we were dealing with was with my ignition voltage which actually increased to 10.6v with key in start position and the correct wiper wire orientation. So I began looking for the missing 2v and noticed what was a intermittent click coming from the flasher switch. Checking out the sound, I first unplugged the unplugged the flasher but the click every 15 or 20 secs remained. When I unplugged the wiper switch, the click that sounded like a quick beat of the flasher stopped. When I checked the wires from the plug, I noticed that the pink power wire was not attached to the connector but I still had power to the wiper motor. That was odd because the wiper motor did work but only on 1 speed. Additionally when I tested for voltage I noticed that I had 12.6v but dropped to 10.6v at the battery when the click sound occurred. Checking further I discovered that the wiper switch was for a 2 speed wiper motor but I have a variable speed wiper installed. What I think was happening is that battery power was being backfed from the ignition switch to the flasher and the wiper when switched on. I have a variable speed wiper switch on order and I believe when I get it installed and everything wired correctly, I will finally get my 12+v to the distributor. Regards, Carl

 

[bigmanjbmopar]

I have marked up the wiring diagrams to what you have traced out, you can see power comes from the fuse box to a 4 way splice with one to the ignition and one to the flasher and one to the wiper. Hope this helps study it closely.

 

[383man]

If it does it with the key off then you know its a system thats hot all the time such as the 12 volt feed to the ign switch and to the headlite switch and to the alt output and so on. First thing I would do is unhook the alt output wire. Ron