69 Coronet Blowing Fuse No. 5

Hello All,

My 69 Coronet continues to blow fuse number 5 (L to R) in my glovebox.

I made a repair to the right inboard tail light socket.....but I have ruled that out, as I insulated both wires and removed the socked from the tail light housing and the bulb from the socket.

When the fuse lets go, the tail lights, license lamp, and instrument cluster lights all go out.
The brake lights, headlights, turns signals, and emergency flashers still work.
That fuse also powers the cigar lighter, so I am going to disconnect that next, and see if that helps....

Anyone had any issues with bad 20a fuses? I think I purchased these from Harbor Freight?

Should I be looking anywhere else?

Thanks,

MB

I would buy fuses from the local auto parts store. If you are really wanting quality, buy the Littlefuse brand.

You sound like you are on the right track; this circuit only feeds the lighter and the lights named above. The lights named all feed through the headlight switch so that is a remote possibility to be worn in a way to be internally shorting. Other than that and the lighter, it is down to a wire chafed somewhere, a short in a bulb, or in a socket or connector.

MB (also)

MB

Thx for the reply

I disconnected the cigar lighter and the trunk light
I remembered that I recently connected the trunk light harness but there is no
bulb in there, and the wire seems to bind on the trunk hinge

I drove the car a bunch today with the lights on all day.
I also put a 15 amp fuse in it and so far no problems

Will c how it goes this next week.

Thx again

MB

Not to be dramatic, but you should be sure to find and fix the problem. The fuse is blowing for a reason and protecting your car from greater damage or a fire. It seems like something is grounding out and shorting the system.

I like your progress so far, and not that you would, but please don't just leave it go and 'assume' since it went away that you solved the problem. Trust me, from experience I say electrical fires are no fun!

Good luck with the fix

sounds to me like the culprit may be the trunk light harness, you did say that it binds on the hinge and that there is no bulb in the socket. it is possible that the live feed in the center of the socket came loose and may be grounding out to the socket housings?? just a thought.

I've had this very same issue with a 1970 Dodge Charger I used to own.

Turned out it was loose screws that hold the metal instrument cluster housing to the metal of the dash frame. Whenever I hit a good bump in the road or crossed a set of railroad tracks....POOF! out go the lights!

Tightened up those housing screws and solved the problem......

Rick@Laysons said:

I've had this very same issue with a 1970 Dodge Charger I used to own.

Turned out it was loose screws that hold the metal instrument cluster housing to the metal of the dash frame. Whenever I hit a good bump in the road or crossed a set of railroad tracks....POOF! out go the lights!

Tightened up those housing screws and solved the problem......

Click to expand...

Hello again....

I took the car out of storage recently, and have been enjoying it a lot.....however, I still have an issue.....
I have completely ruled out the repair I did on the taillight socket....and the cigar lighter has been disconnected, so I am going to have to look at the headlight switch....

I had all my harnesses cleaned and restored by Mr. Heaterbox in Canada....They also cleaned and restored all my dash switches....

I have noticed a pattern....the fuse seems to blow when I am stopped at a stop sign or light....and when I push on the gas pedal, the ammeter goes from a discharge to a charge...

Then I see the headlights flicker, and the fuse lets go. The funny thing is the headlights continue to work after the fuse blows....my brake lights work...just the tail lights (dim setting), the instrument cluster lights, and the cigar lighter are affected....

any other thoughts? I thought it may be an alternator problem, but if so, why is it taking out just that one fuse? The only light I ever see "flicker" is the light in the steering column that shows what gear your tranny is in.....

maybe something in the steering column, huh?

Harbor Freight fuses have been recalled for false blows. So get rid of them.

The ammeter going from discharge to charge when you go from idle to cruise or accelerating, within reason. You should use a voltmeter to check the voltage across the battery when at normal idle versus FAST idle (low versus high RPM's). You want to make sure that the alterntor is not charging excessively; it should be 13.7 to 14.3 volts across the battery at fast idle and warmed up for a standard Mopar charging system. If you get a much high voltage, then that could possibly blow the fuse.

The headlights are not on a fuse so they should continue to work unless the fusible link blows out. The circuits you name that fail connect as follows:
- The cig lighter works direct off of that fuse
- That fuse also feeds the B2 terminal on the headlight switch, with feeds the instrument lamps through the dimmer in the headlight switch and then through another fuse (the INST fuse), and also feeds to taillights from the headlight switch.

So the short could be anywhere that the taillight circuit goes or the cig lighter or, less likely the instrument lamp lines. Disconnect the cig lighter and the 6 pin connector behind the driver's die kick panel going to the rear light and see if that makes the short go away.

Another thing to check would be the running lights. While working on my Niece's 70 Challenger, I had the same issue with blowing the tail light fuse. It turned out to be the left front running light that was shorting out intermittently. You need to isolate everything in the circuit and go from there. Not fun!

Guys.....all great stuff.....thanks very much....

I have the car out of storage now, and am going to start isolating things....

I started looking at the tail light sockets....no visible signs of arcing....no black spots.....

I am next going to look at the front lower turn signal lamps....if nothing looks amiss there, I am going to remove the headlight switch....

Is there any kind of test I can use to determine if the switch is bad? I seem to remember reading somewhere that that switch has some internal stuff that can go bad.....
Anything else I can look for?

thanks,

Mark

I doubt if it's the switch because there are two black wires on the same terminal of the light switch for the parking/license/etc. lights. In simple terms, one black wire feeds the rear lights via the connector behind the kick panel and the other black wire feeds the front parking lights via the bulkhead connector. I would think according to the diagram, your front parking lights would also be out. The power fused power feed to the light switch is pink and the cigarette lighter is red. Both are fed from the same fuse.
The power for the dash lights passes from the light switch to the Panel switch. According to the diagram, the panel switch is fed by the black wire that also feeds the front parking lights.

http://www.mymopar.com/downloads/1969/69CoronetA.JPG
http://www.mymopar.com/downloads/1969/69CoronetB.JPG

Guys......

Thx for replies...... All great stuff

I replaced the 20A fuse with a 15A fuse for extra protection
I then reseated all of the rear tail light bulbs.... I didn't notice any signs of
burning or shorts.
I then ran my dimmer switch up and down several times checking it's operation.
I reset my dash light intensity and have driven the car several times at night with no issues.
Perhaps it was a fault in the dimmer switch
I will keep an eye on it and will spray dimmer switch with contact cleaner if the problem resurfaces

Happy Fourth to all....

MB