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MG MGA - Turn Signals Won't Work -HELP!

I cannot get my turn signals to work. My car is a 1500. I have LED taillights/brake lights and have the required electronic flasher. I have gone through Barney's website thoroughly. At first, I was trying to use my original turn signal relay. I thought that it might be the problem so I bought one of Moss's solid state turn signal relay and it doesn't work either. The taillights, brake lights and side lights all work but the dash indicator light doesn't come on.

I have checked continuity and I have power to the green wire that attaches to the signal switch. I tested continuity through the turn signal switch and it is good. I have tested everything I can figure out to test and still cannot get my turn signals to work.

One thing I haven't done is add a dedicated ground to the indicator lamp. If this is not properly grounded, will it prevent the turn signals from working altogether or just the indicator lamp? Can anyone think of something I'm overlooking?

Jim
JL Cheatham

A good earth is I pretty essential particularly when electronics are involved as they are usually more voltage sensitive. I would get a long lead on a known good earth and touch the bodies of each lamp and see if this makes a difference. Are all sidelight equally bright? If not this would tell you where to start.

Paul
Paul Dean

Grab the test light and start touching relay terminals to see what has power and what not. See diagnostics here: http://mgaguru.com/mgtech/electric/et105.htm

Notice the relay unit must be grounded on the body for the 9th electrical connection.

Disconnect one of the primary terminals of the ignition coil so you don't burn the coil while testing. Switch on. Test light on flasher unit terminal B to verify power input. Jumper between flasher unit B and P should make dash lamp illuminate. If it doesn't, then fix the dash lamp before proceeding.

When the dash lamp works with the jumper, but doesn't flash normally then the flasher unit is not cycling. Get two standard turn signal or brake light bulbs (21 watt incandescent bulbs), connect those in parallel for 42 watt load, and connect those between flasher unit "L" and ground. If it doesn't flash you have a bad flasher unit. A heavy duty flasher unit should flash with anything from 1 to 6 bulbs connected. An electronic flasher unit should flash with minimal load, one incandescent bulb or two led bulbs.

Jumper power to relay terminals 2, 3, 6, 7 to test four corner lamps individually. You already verified the rear lamps work because the brake light work. Even if the front lamps don't work, the rear lamps should illuminate when the signals are switched on.

Jumper power to relay terminal 4 for right signal, and terminal 8 for left signal. If that works, then you have a problem with the signal switch wiring. Use test light on 4 and 8 to see if the switch is working. If you don't get power to 4 and 8, fix the switch wiring. Again, the relay case must be grounded to make the relays click. If no click, then the problem is in the switch or relay trigger circuit.

Let us know how you make out this far along, and if still not working get back to us again.
barneymg

Don't forget to reconnect your coil when you've finished testing.
Dave O'Neill 2

Thanks everyone. I made a dedicated ground wire and connected it to the bottom screw that holds the signal relay to the firewall. I connected the other end to the stud on the back of the speedometer that the ground wire from the harness is connected.

I turned on the ignition and then turned on the signal switch and everything works perfectly!

Now on to the other gremlins.

Jim
JL Cheatham

No need for the wire, if you scrape a little paint off the back of the firewall for the screw to make the ground connection.
barneymg

This thread was discussed between 30/04/2017 and 04/05/2017

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