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MG MGA - Front Turn Signals Won't Work

Left and right front parking lights light up when the headlight knob is pulled but when turn signal lever is pushed either right or left the rear tail lights flash but the front lights don't.blink. They stay on. In other words they do everything but blink.
Can't figure it out.
Mike Razor

1500 or 1600?

If it is the 1500 and the rear lights blink, I think you may be miswired at the relay or in one of the in-line bullet junctions.

Do the front signals flash without the running lights on? Perhaps you have the wrong element wired to the running lights. These stay on all the time, even when the turn signal is supposed to be flashing too. If you wired the high power element to the running light circuit, the low power element may be flashing but being much dimmer, difficult to see.

Chuck Schaefer

It is a 1959 MGA 1500. All was working fine for several years and then just quit. The rear two flash when the switch is turned. Neither of the front ones will flash. The fronts won't flash regardless of weather the lights or on or not. I wonder if it could be the flasher unit? I went back and read some of the old post on this. Learned something, to disconnect the coil. Didn't do that and came home last night and found the switch still on.
But, there were several references to the flasher unit. Seems like that would affect the front and the back.
Mike Razor

A bit of an old chestnut, but make sure you have a GOOD earth to the front light units. A bad earth will allow the sidelights to work but not enough current will flow to light the flasher filaments.
Lindsay Sampford

If it just quit without any wiring changes, then is probably the relay. There are separate contacts and terminals on the relay for each of the 4 lights. Possibly just cleaning the relay contacts would fix it.

Look on Barney's site as he has several pages about the relay. Here is one of them. http://www.mgaguru.com/mgtech/electric/et105.htm

Jeff Schultz

The flasher unit is not the issue. there is a single load wire that feeds either the RH or LH turn signals both front and rear. Very odd that both the LF and RF turn signals stoped working at the same time. They are separate circuits within the real box.

Take a test light or analog meter to the screw head at terminal #6 while the LH signals should be flashing and see what happens. If you get continuous 0 volts or no light from the test light, then I would suspect that cleaning/adjusting the contact points internal to the relay is in order. If things are properly working, then you should be getting alternating 0V and 12V. If this is the case, then check your bulb/sockets. Similarly with terminal #2 and the RH signal.

If the rear signals flash, as you say they are, then the coils internal to the relay box should be good.
Chuck Schaefer

a bit obvious (and coincidence if they went together) but did you check the bulbs?
Neil McGurk

Mike, -- Parking lights and turn signals are totally unrelated, working from different power circuits. Parking lights un-fused and work with ignition switch off. Turn signals are fused and work only with ignition switch on. This could be a little bit of a fooler because the 1500 parking light and turn signal are in the same bulb, but using two different filaments (same as if it was two different bulbs with a common ground connection).

Start with the all important electrical diagram here:
http://mgaguru.com/mgtech/electric/circ_f2.htm

Note first that the original flasher unit should flash only when there are two bulbs connected. If one bulb burns out or is disconnected the thing should stop flashing as a warning to the driver. Since yours seems to flash with only one bulb working (rear only), I suspect that someone has installed an incorrect "heavy duty" flasher unit. This is intended for use with 4-way hazard flashers and will flash at same rate with any number of bulbs connected. Since the flasher unit does flash, the front and rear lamps should flash together. This most likely not any problem with the flasher unit. For testing of the flasher unit see here:
http://mgaguru.com/mgtech/electric/et104.htm

Back to the relay issue, grab a test light and connect the tail to chassis ground. Ignition switch on, right turn signals on, probe terminals 2 and 3 on the relay. With left signals on, probe terminals 6 and 7 on the relay. All four of these terminals should make the test light flash. Terminals 3 and 7 are for the rear lights which obviously do work. Terminals 2 and 6 are for the front lights which do not work.

If 2 and 6 flash, but the front lights do not, then you have wiring issues between the relay and the front lamps. You can test these circuits by connecting a hot jumper wire to 2 and 6 to see if the front lamps will light up.

If 2 and 6 do not flash, then you have contact issues inside the relay unit. These relays do sometimes cause problems when 30 to 50 years old. Sometimes you can bend the contact arm slightly to get two contacts at once. Other times it may ultimately be a lost cause requiring repair or replacement of the relay unit.

For debugging of the relay unit see here:
http://mgaguru.com/mgtech/electric/et105.htm

For rebuilding of the relay unit see here:
http://mgaguru.com/mgtech/electric/ts202.htm
This is functionally the same as the new Moss Motors "upgraded repro" relay unit, except theirs is on a circuit board, and my (cheap) hand wired unit was done a few year earlier.
Barney Gaylord

Just because I found one in my parts bin I replaced the flasher unit. All this did was cause the rear lights to blink really fast and the green light on the dash to glow constantly. Checked the relay and both are clicking very well.
Mike Razor

Check everything out. Must be a break between the relay and the front lights. Had to bypass with new wire. Put in a new flasher from local parts house. Everything works except the indicator light has a faint glow all the time.
Any hints?
Mike Razor

Very odd. Wires between relay and front lights are a continuous run with no intermediate connectors. If a bypass wire makes any difference, then one of the end connectors must have been bad. Parking lights DO have circuit splitter snap connectors, one near the starter switch, one at RF corner and one at RR corner.

Indicator lamp with a slight glow can only get power from the flasher unit. That should be open circuit when at rest. If the lamp glows you may have the wrong flasher unit for the application.
Barney Gaylord

Just realized how old my email address was on this post.
Anyway, I used the exact flasher that was on the car when I got it. I just don't know what else it could be. At least I have turn signals, brake lights, running lights when I am suppose to. It may have been in the relay. We jacked around with it as well. I took it off and filed the points and we bent it ever so slightly. Of course, the lights didn't work until we put a new wire in. I hate doing that wish I could have found the fault in the harness just makes it harder to trace stuff later.
Mike Razor

This thread was discussed between 22/07/2010 and 26/07/2010

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