Indicators stopped working - '72 roadster

[timgrant]

MGB Roadster 1972. The indicators have stopped working, although the hazzard work properly. The brake lights and reversing lights continue to work. I have a feeling they were starting to work slowly and intermittently in the past week or so.

Am I right in thinking that it's not the fuse or the bulbs for reasons above and likely to be the flasher unit?

Can you tell me where it is and do you agree?

Many thanks

Tim

[Vic Butler]

I believe without looking at a wiring diagram that the hazards use a different relay because a heavier duty one is needed.
It's likely to be the relay. It's best to replace it with an electronic one as they're more reliable than the old bi metallic strip type.

[Paul Scott]

Hi Tim,
Wiring Diagrams can be found here http://www.advanceautowire.com/mgb.pdf

I believe the flasher unit is under the steering column and hazard flasher behind central console.
Some indicator issues are caused by the hazard switch. In the off position it works as a bridge to direct power to the normal flasher unit. Sometimes switching it on and off several times will clean up the contacts inside.

Regards
Paul

[ChargedAutoGT]

same symptoms - happened to me - just recently. mine was intermittent and drove me mad.

the connector on the hazard switch had worked loose and pin7 was making/breaking the circuit for indicators, but hazzards were fine.

G

[Michael Barclay]

Hi Tim
I think Paul is on the right track. As the brake lights work and hazard lights work I think the problem is limited to either the flasher unit or indicator stalk.
The hazard lights use a separate flasher unit located behind the centre consol. The normal flasher unit is located under the dash mounted on the bulkhead to the left of the wiper motor. The regular flasher circuit gets its 12V feed from the Hazard warning switch. These switches are known to suffer from sticking contacts preventing 12 V from getting to the regular flasher circuit. Try operating the Hazard switch several time to see if this fixes the problem. If not, locate the flasher unit under the dash and pull off the Green wire. With the ignition on check with a multimeter or a bulb to see if you have 12 V present. If no you will need to go back and check the operation of the Hazard warning switch. If yes then remove the other wire from the flasher unit (Light green/brown) and join it to the green wire. With the ignition on and the direction indicator switch moved to either left or right position you should see the appropriate front and rear lights illuminate. If this happens then the flasher unit is faulty. If not you need to investigate the indicator switch.
Hope this helps.
Best regards
Mike Barclay

[timgrant]

Hi Tim
I think Paul is on the right track. As the brake lights work and hazard lights work I think the problem is limited to either the flasher unit or indicator stalk.
The hazard lights use a separate flasher unit located behind the centre consol. The normal flasher unit is located under the dash mounted on the bulkhead to the left of the wiper motor. The regular flasher circuit gets its 12V feed from the Hazard warning switch. These switches are known to suffer from sticking contacts preventing 12 V from getting to the regular flasher circuit. Try operating the Hazard switch several time to see if this fixes the problem. If not, locate the flasher unit under the dash and pull off the Green wire. With the ignition on check with a multimeter or a bulb to see if you have 12 V present. If no you will need to go back and check the operation of the Hazard warning switch. If yes then remove the other wire from the flasher unit (Light green/brown) and join it to the green wire. With the ignition on and the direction indicator switch moved to either left or right position you should see the appropriate front and rear lights illuminate. If this happens then the flasher unit is faulty. If not you need to investigate the indicator switch.
Hope this helps.
Best regards
Mike Barclay

Many thanks everybody................ especially Mike Barclay for your clear and helful advice. I've followed Mikes instructions and diagnosed a faulty flasher unit. I've ordered a replacement Lucas and an electronic one. Should be back on the road in the sunshine in a day or too!