[ChiefBre9]

The 7.5 amp fuse(white) keeps blowing when I turn on parking lights, This is fuse # 9, which circuit is RH front parking light & side marker, engine bay light, and LH rear parking light & LH rear side marker. It worked just fine a few months ago. It appears to have a direct short; I have wiring diagram & have changed all inop bulbs, + repaired the trunk mounted stop
light so it now works. Only other modification was to cut power wire to power mirrors, as they never worked, and to unplug clock as it never worked either. I attached my ammeter to #9 fuse, turned on switch & observed a draw of just over 7 amps. Connected test light to upper & lower fuse contacts & the test light lights up. All other lights, including the glove box & courtesy floor lights work as supposed to. Next, I am going to try the 16 amp fuse; would appreciate any suggestions. BTW, the RH & RR turn signals work fine. HELP!

Chief Bre

 

[pantera928]

The 7.5 amp fuse(white) keeps blowing when I turn on parking lights, This is fuse # 9, which circuit is RH front parking light & side marker, engine bay light, and LH rear parking light & LH rear side marker. It worked just fine a few months ago. It appears to have a direct short; I have wiring diagram & have changed all inop bulbs, + repaired the trunk mounted stop
light so it now works. Only other modification was to cut power wire to power mirrors, as they never worked, and to unplug clock as it never worked either. I attached my ammeter to #9 fuse, turned on switch & observed a draw of just over 7 amps. Connected test light to upper & lower fuse contacts & the test light lights up. All other lights, including the glove box & courtesy floor lights work as supposed to. Next, I am going to try the 16 amp fuse; would appreciate any suggestions. BTW, the RH & RR turn signals work fine. HELP!

Chief Bre

That is a needle in a haystack to find. Since you have the wiring diagram, I would eliminate all the loads on that fuse and reconnect them one by one to see which one causes the excessive smp draw. You could do this by disconnecting the harness connectors to all of those lights and then start plugging them back in one by one with your amp meter connected. Is it an inductive clamp meter that you can clamp over the wires leaving the fuse?

 

[ChiefBre9]

That is a needle in a haystack to find. Since you have the wiring diagram, I would eliminate all the loads on that fuse and reconnect them one by one to see which one causes the excessive smp draw. You could do this by disconnecting the harness connectors to all of those lights and then start plugging them back in one by one with your amp meter connected. Is it an inductive clamp meter that you can clamp over the wires leaving the fuse?

I do have an inductive clamp meter, but I don't know where to put the clamp over the wires; does the current leave the fuse on top or on the bottom?

 

[pantera928]

I do have an inductive clamp meter, but I don't know where to put the clamp over the wires; does the current leave the fuse on top or on the bottom?

I believe through the bottom but if you take a test light or volt meter and test both sides of the blown fuse, whichever side still has voltage is where it comes in and where it isn’t there is where it goes out. Or do the same with the fuse removed.

 

[Jim G]

Did you change either parking light bulb?

 

[bianchi2]

wet your finger and start testing (never mind,,i got that repair advice from the ' red green show') doest work

 

[spiderserie4]

fuse 9 is also the number plate lights, iirc.......that is powered via that 3 pin connector on left side of trunk lid (and corresponding half on the edge of trunk opening)...which is also the 3rd brake light, which you were working on....
I'd check that connector.

Basically remove all bulbs on that circuit, if fuse is still intact, then put one back in at a time and see which blows the fuse.

 

[ChiefBre9]

Did you change either parking light bulb?

Yep, I did. In fact I probably changed 3/4 of all the bills. Obviously, it wasn't driven at night.

 

[ChiefBre9]

fuse 9 is also the number plate lights, iirc.......that is powered via that 3 pin connector on left side of trunk lid (and corresponding half on the edge of trunk opening)...which is also the 3rd brake light, which you were working on....
I'd check that connector.

Basically remove all bulbs on that circuit, if fuse is still intact, then put one back in at a time and see which blows the fuse.

Excellent advice! Don't know why I did not see that #9 controls the license plate lights. The third brake light's socket
was damaged,. so I bought one @ auto parts store & wired it in, I have a thing about lights that don't work...& other things as well. First on my list today to check!

Chief Bre9

 

[Jim G]

On the rear light bulb holders. Its easy to catch the ground strip in the bulb socket when inserting a new bulb. its the copper strip that runs up the side of the bulb holder. The bulb will sometimes catch the strip and push it down into the positive strip giving you the short.

 

[pantera928]

Any luck yet?

 

[ChiefBre9]

On the rear light bulb holders. Its easy to catch the ground strip in the bulb socket when inserting a new bulb. its the copper strip that runs up the side of the bulb holder. The bulb will sometimes catch the strip and push it down into the positive strip giving you the short.

I'll also check that, in addition to the other tips I have received. It is such a mystery how, after working as normal, the circuit could develop a short, except that I had to replace the third brake light & did some other bulb replacements around the trunk. I think chances are veery good that the "short" is in that area. Couldn't be as bad as the 1949 MGTC I restored for a friend; the car sat in an unheated warehouse for 30 years, and EVERY wire under the dash had been cut!

Chief Bre9

Any luck yet?

I think I am close...found the yellow wire with black stripe disconnected where it mates up with the three buttons on the trunk lid, and it is the obvious culprit, as it could have easily been touching the body inside the trunk. I checked the
continuity with multimeter between yellow/black wire terminal on the engine bay light, and sure enough no resistance.
In the meantime, I managed to pull loose the clamped connection for the third brake light, so I decided to take the spoiler off the trunk & solder the wires...then found out my Weller solder gun tip was caput, but found a new one at the 2nd hardware store & finished the job, finally! I had removed the LR tail light bulb, but checked it & the ground strip is not interfering & shorting out to the + connection. I'm done for the day now. tomorrow I will install a new fuse & see what happens.

Chief Bre9

 

[ChiefBre9]

I'll also check that, in addition to the other tips I have received. It is such a mystery how, after working as normal, the circuit could develop a short, except that I had to replace the third brake light & did some other bulb replacements around the trunk. I think chances are veery good that the "short" is in that area. Couldn't be as bad as the 1949 MGTC I restored for a friend; the car sat in an unheated warehouse for 30 years, and EVERY wire under the dash had been cut!

Chief Bre9

I think I am close...found the yellow wire with black stripe disconnected where it mates up with the three buttons on the trunk lid, and it is the obvious culprit, as it could have easily been touching the body inside the trunk. I checked the
continuity with multimeter between yellow/black wire terminal on the engine bay light, and sure enough no resistance.
In the meantime, I managed to pull loose the clamped connection for the third brake light, so I decided to take the spoiler off the trunk & solder the wires...then found out my Weller solder gun tip was caput, but found a new one at the 2nd hardware store & finished the job, finally! I had removed the LR tail light bulb, but checked it & the ground strip is not interfering & shorting out to the + connection. I'm done for the day now. tomorrow I will install a new fuse & see what happens.

Chief Bre9

Eureka! Success! The short indeed was that the yellow w/black stripe wire had become detached where it connects to the
three connection block in the lower part of the trunk, and it was obviously touching the body. So I tightened up the spade connector & covered all three connections with electrical tape. Done!

Chief Bre9

 

[pantera928]

Eureka! Success! The short indeed was that the yellow w/black stripe wire had become detached where it connects to the
three connection block in the lower part of the trunk, and it was obviously touching the body. So I tightened up the spade connector & covered all three connections with electrical tape. Done!

Chief Bre9

Good times and good work.🥂

 

[ChiefBre9]

Good times and good work.🥂

Good times and good work.🥂

Good times and good work.🥂

Thanks, Pantera928. But it took a few fuses & too long to go back to where I was working around the trunk to find the
disconnected wire which was causing the direct short!

Chief Bre9

 

[pantera928]

Thanks, Pantera928. But it took a few fuses & too long to go back to where I was working around the trunk to find the
disconnected wire which was causing the direct short!

Chief Bre9

Sometimes electrical issue are that way. That is why i love them so!

 

[ChiefBre9]

It's just great to finally solve the problem.....

Chief Bre9