Aftermarket radio install ground wire short

[Chall73]

Hi folks,
While installing an aftermarket new Kenwood stereo in my 73 Challenger, I caused a short with the black ground wire and the radio went dead. Checked the fuse on the new radio and the fuse box on the firewall. All fuses look OK, any ideas to what it could be? Also I used the cigar lighter wire for the constant power battery yellow wire.
Any help would be appreciated! Thank you, Mark

 

[MoparCarGuy]

Hi folks,
While installing an aftermarket new Kenwood stereo in my 73 Challenger, I caused a short with the black ground wire and the radio went dead. Checked the fuse on the new radio and the fuse box on the firewall. All fuses look OK, any ideas to what it could be? Also I used the cigar lighter wire for the constant power battery yellow wire.
Any help would be appreciated! Thank you, Mark

When you say "short with the black ground wire", do you mean you touched the black ground wire to 12VDC power?
We need to see your circuit (wiring) diagram for the Kenwood radio model you are installing to see what might have been damaged, if anything.

 

[Chall73]

Thank you for responding so quickly Moparcarguy. I moved the ground wire to another part of the firewall which caused a spark and the radio shut off. The 12 volt hot wire never touched the ground wire.
I will try to attach the wiring diagram.

 

[Bret Schneider]

The ground wire (f) is shorted to either the 12v battery wire (e) or possibly the acc wire (d) if you happened to have the key on when the spark occurred. Could be shorting in the harness. Possibly internally in the radio. Not really sure why the fuse didn't pop on e or d. Even a 25 amp fuse should have been blown when the wire sparked. With d, e, f, and the radio plug disconnected, take an ohmmeter and see if you have continuity between f and either d or e. If so the problem is in the harness. If not, plug in the radio connector and check again for continuity between those wires. Somehow battery voltage is getting on f.

 

[Challenger RTA]

First mistake most make. Black wires are also power. most grounds are short trip to ground. Sounds like there are a few puns there. The black wire on the radio would go directly to the body. There are no grounds per se in the cars wiring harness. Except the headlight harness and the battery ground. Where was the red wire hooked up at. If all the leads were not hook up and you completed the circuit it might have shorted one out. Like the antenna control. Was the radio on?

 

[MoparCarGuy]

Thank you for responding so quickly Moparcarguy. I moved the ground wire to another part of the firewall which caused a spark and the radio shut off. The 12 volt hot wire never touched the ground wire.
I will try to attach the wiring diagram.

Starting over with what changed, you said you "moved the ground wire to another part of the firewall". The diagram has the circled f black wire connected to Ground (GND). The radio was working before you moved the f black wire, so move it back to the previous firewall location and see what happens. Moving the GND wire would not cause a problem unless the new location did not provide a proper body/chassis ground. The battery is also chassis grounded and that completes the DC circuit.

Before rechecking the GND is good, verify you still have 12VDC at the c (ACC RED IGN) wire with the ignition switch ON AND the e (BATT YELLOW) wire.
Also, make sure the Radio is turned ON, then:
Check if the Radio works with the f black wire at the original GND location. Does the Radio work? If so, SUCCESS.
IF not:
- Make sure the new GND location is clean and bare metal.
- Reconnect the black wire to the new GND location. Check the radio for operation.

Check if the Radio works with the f black wire at the new GND location. Does the Radio work?

Let us know what results you get and we can then proceed with further troubleshooting. Hopefully, the radio itself is fine.

 

[Chall73]

Thank you guys, I am checking all of the recommendations you made in response to my radio question. I am in the process of checking the continuity as requested.

And yes the key was turned to the on position and the radio was on and working when the spark occurred.
Thank you all again and I will give an update as soon as possible.

 

[Chall73]

Hey guys, thank you again for your help! The radio is now working! All of the electrical tests checked out OK.
The red wire and the yellow wire were connected solidly.
Once the black wire was grounded as it should have been in the beginning to clean bare metal, now the radio is working great. I appreciate your input!