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71 'B turn signal/brake light gremlin

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71 'B turn signal/brake light gremlin
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  This topic is about my 1971 MG MGB
MG-driver Avatar
MG-driver Tom Sim
Richardson, TX, USA   USA
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1971 MG MGB
Hi All! First post here, but have been driving my MGB for 20 years or so. My annual inspection is due this month, and I've found it is best to do a "pre-inspection" inspection myself. I have a problem with the wiring somewhere. I'll attempt to describe what happens.

Givens
-headlights work in all scenarios.
-side markers work in all scenarios.
-license plate lights work in all scenarios.

Issues
-reverse lights do not come on at all.
-turn signal left, will come on and not blink (front back and on dash).
-turn signal right, will come on and flash (front back and dash), speed increasing/decreasing relative to engine rpm's.
-headlights on, rear lights on. Step on brakes, passenger side illuminates and driver side goes off.
-hazards on, headlights on, passenger side works fine. driver side brake light flashes opposite the hazard. driver side flashes, but at maybe 10-20% brightness. hazard flashers on dash flash. The photo attached is of this oddity. The bottom light is as bright as it gets, the top light as dim as it gets.

The windshield wipers work, but are so doggedly slow. If the windshield is dry they won't move at all, or stop halfway through a cycle. The dash gauge lights work and dim, and hazard indicator works. high-beam and ignition indicators also work. Horns also work, as does fuel pump. (Insert obligatory *knock on wood*)

Electricity and I are not the best of friends! I fear I may have to take it to a local British car shop, but thought I'd try some thoughts here first. Thanks in advance!


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Ex-Calif Gold Member Dan D
Dayton, OH, USA   USA
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1968 MG MGB GT "Bart - Yellow And Naughty"
1977 MG MGB "Red Betty"
2006 Suzuki Grand Vitara "Suzi Q"
2012 Jeep Liberty "Tommy The Tank"
To me this sounds like a lot of dirty connections. Electricity follows the path of least resistance. If the path you want is corroded, the electricty finds "sneaker" circuits.

I have found weird things happen on the MG when bullets, grounds, connectors, bulb sockets etc. are corroded.

I spent a saturday morning on each car after purchase cleaning all connections on the car. Gather appropriate set of cleaning tools, round stone in a cordless drill for bulb sockets, points files for female spades, spare female bullet connectors (cheap enough to replace vs. cleaning.

Turns flashing on one direction and not another is a classic sign of high resistance.



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tomgrigsby Avatar
tomgrigsby Tom Grigsby
Ivor, VA, USA   USA
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1971 MG MGB GT "The Blight"
1979 MG MGB "The NewB"
In reply to # 3574704 by MG-driver Hi All! First post here, but have been driving my MGB for 20 years or so. My annual inspection is due this month, and I've found it is best to do a "pre-inspection" inspection myself. I have a problem with the wiring somewhere. I'll attempt to describe what happens.

Givens
-headlights work in all scenarios.
-side markers work in all scenarios.
-license plate lights work in all scenarios.

Issues
-reverse lights do not come on at all.
-turn signal left, will come on and not blink (front back and on dash).
-turn signal right, will come on and flash (front back and dash), speed increasing/decreasing relative to engine rpm's.
-headlights on, rear lights on. Step on brakes, passenger side illuminates and driver side goes off.
-hazards on, headlights on, passenger side works fine. driver side brake light flashes opposite the hazard. driver side flashes, but at maybe 10-20% brightness. hazard flashers on dash flash. The photo attached is of this oddity. The bottom light is as bright as it gets, the top light as dim as it gets.

The windshield wipers work, but are so doggedly slow. If the windshield is dry they won't move at all, or stop halfway through a cycle. The dash gauge lights work and dim, and hazard indicator works. high-beam and ignition indicators also work. Horns also work, as does fuel pump. (Insert obligatory *knock on wood*)

Electricity and I are not the best of friends! I fear I may have to take it to a local British car shop, but thought I'd try some thoughts here first. Thanks in advance!
The brake lights, and all other lights for that matter, get their ground connection through the screws and contact with the body/chassis. The flasher won't make the turn signals flash if they don't draw enough current. That's why flashers don't when one bulb is burned out. Since passenger flashes it means the flasher unit under the dash is probably OK. Most likely you bad/rusty ground at the driver's side tail light assembly. Remove it and clean all connections, light sockets etc. Do only the driver's side first, so that if something changes, you'll know where you were working. Once that's fixed, or at least still doing the same thing, clean the other one.

As for the reverse lights, it is a separate circuit. It could be the grounds or it could be the switch at the transmission is disconnected or failed.

Wipers could be poor connections, failing motor, and/or binding linkage (needs lubrication) On my 71, it was the linkage, but I never got them to work very well. You can pull the whole thing without removing the dash etc. Might want to do a search on the wiper system.

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Cruisedon66 Avatar
Cruisedon66 Pete W
St. Louis, MO, USA   USA
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1976 MG MGB
See photo in post #5. A gun cleaning brush on a drill works great.

http://www.mgexp.com/phorum/read.php?1,3568577,3568598#msg-3568598

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albeegreen1 Avatar
albeegreen1 Silver Member bob tresch
bordentown, NJ, USA   USA
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1972 MG MGB MkIII "ALBERT"
Tom: Along with cleaning your outer bulb sockets, pull the steering wheel cowl carefully and clean the turn signal switch and the wire plugs. Some contact cleaner is a good step. Make sure you reconnect them tightly and evenly. Compressed air helps. Hope this helps. Use dielectric grease on your lens sockets after brushing them out nice and shiny.



"Only those who have patience to do simple things perfectly ever acquire the skill to do difficult things easily"
James J. Corbett

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Sinewave Avatar
Sinewave T. Keith Vezina
Kenner, LA, USA   USA
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To address the taillight issue only, I had this same problem a few years ago. What I discovered was that the lamp socket was not grounding to the taillight housing. This caused the brake light filament to seek a ground through the park light filament. Easy enough to test, just run a jumper from the outside of the light socket to a good ground. I fixed it by adding some solder to the crimp where the socket is joined to the taillight housing.



T. Keith Vezina
British Motoring Club New Orleans
1976 MGB, 1976 MGB Trailer & 1978 MGB V8

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MG-driver Avatar
MG-driver Tom Sim
Richardson, TX, USA   USA
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1971 MG MGB
Thank you everyone for your help! I cleaned all the connections for the driver side, and it all made it work! Removing the steering column cowl would've been the next step, should the other connections not have worked. Well, the reverse lights will take some more effort, but they are not listed on the State's inspection checklist, so I wasn't too worried.

Funny thing these connections...Murphy's Law or not knocking on wood though. I took the car out for a double-check/celebratory evening cruise. Stopped at a empty parking lot, and everything was working great. I pull out and onto a major street, I notice that the ignition light has the faintest glow to it, accompanied by a brief funny smell. The faint orange goes away, as does the smell. A few blocks later a fellow motorist come up next to me yelling "your lights man, your lights!" I was thinking to myself proudly "why yes, I just got them working. Wait, he has no idea, what does he mean?" So I pull off into the next neighborhood street. Yep, headlights out. Brake running lights out. Whole passenger side out. Everything. I checked all the fuses when I hobbled home, and those are all ok. The headlight switch, however, is stuck on. Guess the halogen pulled too much current and fried the switch. Yippie. I disconnected the battery, just to be safe.

I should've run to the inspection place the moment it was all working!

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