Vintage Mustang Forums banner

21 - 40 of 64 Posts

·
Registered
Joined
·
786 Posts
With all the work you've already done, I would venture a guess that your issue won't be a component. You probably have a wiring problem. I had something similar and found burnt wires in the headlight harness where it runs through the lower radiator core support. As someone said above, just enough to cause a draw without being enough to blow a fuse. Now, I'm not sure how many places the harness can be separated in your car, but finding and unplugging those main harnesses one at a time will help isolate the issue.
 

·
Registered
Joined
·
297 Posts
Discussion Starter #23
Okay thanks everyone, I’ll start with the fuse link and go from there. In the meantime I installed a battery disconnect to make it easier while I narrow it down



Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
297 Posts
Discussion Starter #24
Well I pulled off all the wires from the solenoid and there is one wire that when connected is drawing the 400-500 ma. It looks like it runs toward the firewall as part of a taped cluster of wires. The hunt begins, but I guess it will be a good time to clean up some old connections and wires because that section of wires looks rather sketchy 🤨


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
775 Posts
That wire powers ignition sw and headlamp sw. It also powers alt which you said you disconnected the 2 wire plug.

Your sure about trunk light, look on the drivers side hinge to see if there is a wire there. I had a sports roof and it had the trunk light. my Mach I has one
 

·
Registered
Joined
·
297 Posts
Discussion Starter #29
That wire powers ignition sw and headlamp sw. It also powers alt which you said you disconnected the 2 wire plug.



Your sure about trunk light, look on the drivers side hinge to see if there is a wire there. I had a sports roof and it had the trunk light. my Mach I has one


I’ll check the trunk today. Also, When I first got the car the headlights flickered and something was loose in that general area near the firewall. 🤨


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
4,157 Posts
I’ll check the trunk today. Also, When I first got the car the headlights flickered and something was loose in that general area near the firewall. 🤨


Sent from my iPhone using Tapatalk
It'd probably in your HL switch or a junction in the wiring to the lights.
 

·
Registered
Joined
·
297 Posts
Discussion Starter #31
That wire powers ignition sw and headlamp sw. It also powers alt which you said you disconnected the 2 wire plug.



Your sure about trunk light, look on the drivers side hinge to see if there is a wire there. I had a sports roof and it had the trunk light. my Mach I has one


Definitely don’t see a trunk light or wire on the hinge. I also checked the connections near the firewall and they are not loose but some are taped so I will probably do some new connections there soon.

I’ll keep looking but so far no smoking gun!


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
8,476 Posts
On my '67 I found that there is a 4 wire splice junction buried inside the main underdash harness. One of the 4 is the main unfused power coming from the solenoid, one is to power the ignition switch, one is power to the headlight switch and I forget where the last one goes. After all of your diagnosis work, I would focus on the ignition switch and the headlight switch, looking for possible shorts internally

To eliminate the obvious, your courtesy lights are not on when the doors are open during your testing?
 

·
Registered
Joined
·
297 Posts
Discussion Starter #34
On my '67 I found that there is a 4 wire splice junction buried inside the main underdash harness. One of the 4 is the main unfused power coming from the solenoid, one is to power the ignition switch, one is power to the headlight switch and I forget where the last one goes. After all of your diagnosis work, I would focus on the ignition switch and the headlight switch, looking for possible shorts internally



To eliminate the obvious, your courtesy lights are not on when the doors are open during your testing?


No they are definitely off. I double checked.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
1,545 Posts
No they are definitely off. I double checked.
Something I found troubleshooting my dash lights was mine was so corroded or worn that even though the switch was on and drawing power the resistance in the switch was enough to draw a bit of current but not so much that I could see the lights in the day or in a lighted shop. The dome worked as expected so I ASSumed the dash lamps were burnt. It turned out to be inside the switch. The temp fix until the part is changed was working it vigorously with a bath of contact cleaner.
 

·
Registered
Joined
·
297 Posts
Discussion Starter #36
I guess i wasn't clear about power from fuse link wire. Disconnect the ignition sw and then the headlamp sw to try to isolate draw.


No you were clear but I’m just a bit confused about what all is powered from that wire and how power gets to the fuse panel. I really need to find a good book to learn some of the electrical basics for the car, which is by far my weakest area. Plus I’m not sure where to disconnect the ignition and lights.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
297 Posts
Discussion Starter #38
Newbie here: Just curious, how did you initially determine that you have a consistent ~420 ma drain?



:nerd:


I learned (from threads on this forum) to disconnect the negative terminal on the battery and use an ammeter to “jump” across (black lead on negative battery terminal and red lead on negative battery cable. The ammeter sees current traveling across and allows conductivity. If you see more than 50 ma then something is drawing too much power when the battery is connected, which will eventually drain your battery. You then narrow down the source by pulling fuses, disconnecting the alternator etc. Be careful about which setting/range the ammeter is on so you don’t overload it and/or blow its fuse. Hopefully I’ve described this accurately but if not others please correct me . And of course I have not yet found it but learning a lot along the way.

The great thing about this car and this forum is that it provides a nice hobby and you learn a lot also. Frustrating sometimes but it’s not exactly a daily driver and I have beer in the garage


Sent from my iPhone using Tapatalk
 
21 - 40 of 64 Posts
Top