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MG MGB Technical - Indicators won't flash

My 1975 RB GT indicators don't flash. Each bulb illuminates but stays on permanently. I've replaced relay but no luck? What next?
P G LIDDER

Step number one for many/most electrical problems: disconnect the battery and wire brush the fuse holders. You may have a weak/bad connection there.
Dan Robinson

This happened to my '79 GT. The problem was caused by a bad connection at the multi-pin connector near the steering column which had loose/dirty/badly fitting pins.
Brian Shaw

If all four light, but don't flash, with two flasher units (strictly speaking they are not relays), then it is probably a bad connection as been stated. However first disconnect one of the spades at the flasher unit to make sure you don't get the lights even glowing. If they still glow with a flasher unit connection disconnected then the flasher unit is being bypassed somehow.

If not that then the next thing to do is flip the hazard flasher switch on and off a few times. The 12v supply to the indicator flasher goes via the hazard switch in the off position, and bad connections in this switch are common as it is rarely used.

If that makes no difference, then it is time to start digging deeper. Assuming they used to work, and just stopped flashing, then it is reasonable to assume the bad connection is somewhere between the column switch, back through the flasher unit, hazard switch, green circuit fuse, ignition switch, down to the solenoid. Test the voltage at each of these points, with the ignition and indicators on, looking for a sudden change in voltage, which will indicate a bad conenction between that and the previous test point. There are many connectors in this route as well as the components mentioned.

If the car is new to you and they have never flashed, then it could be any number of things, or combination of things, including bad connections and/or incorrect bulbs anywhere between the indicator switch and the corners of the car, including the light unit earths. The rears pick up an earth from their physical fixings to the rear wings, the fronts on an RB have an earth wire that joins with the headlights and goes to an earthing point by the fusebox. If this earthing point, or the bullet connector by the right-hand headlight is the cause, then it will affect both sides.
Paul Hunt

First I would check and see if the four way flashers work on all four corners. If so then the rocker switch should be checked for continuity across the two lower green wire connections, If there is continuity across that switch then the problem lies further down the line. Is it possible that there hs been a cross over of connections at the flasher unit itself?
Sandy
conrad sanders

Poor earth connections at the bulb holders can cause this problem.

On a slightly different track I recently had a flasher unit go duff and when I asked my MG people for a replacement they suggested a Ring RFL3 electronic verison instead. A very worthwhile upgrade. Now the flashers always operate at the correct rate wether the engine is off, ticking over or reving. Makes a great difference at the traffic lights! No wiring changes apart from adding an earth wire to 31 terminal.
Graham Gilmore

The modern electronic flashers *are* a lot less sensitive to voltage and current than the original type it is true. But if you are getting slow or non-flashing because of bad connections, then you will still have those bad connections with an electronic flasher, and they will be reducing the light intensity with *either* type of flasher. Much better to find and fix the bad connections, they will only get worse and your lights dimmer.

Whilst rubber bumper front flasher units do share a wired ground so a single bad connection along this can affect both sides equally, it is also shared with the headlights and parking lights making finding and fixing it far more important than simply getting round it by fitting an electronic flasher. Chrome bumper fronts, and all rears, have independant earths from the physical fixings so you would need two or more separate ones to affect both sides. It all depends on whether this suddenly started happening, in which case two separate faults are unlikely, or the car is new to this owner and has always done it, in which case there could be any number of faults.
Paul Hunt

This thread was discussed between 17/12/2008 and 24/12/2008

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