740 turn signal problem - buzzing noise, relay issue?

[Call me Bob]

I have a 1991 740 which has just developed an indicator (turn signal)
fault.

The problem began recently as a grumbling buzzing noise, sounding in
time with the blinking of the indicator light. The signal now also
intermittently cuts out and does not work at all. This also affects
the seat belt not deployed dash signal, which seems to be on the same
circuit.

I've had a look at the fuse behind the ashtray and it is fine, but the
buzzing noise can definitely be heard from the fuse box area now the
front cover is off.

I found that wiggling the whole fuse box when the turn signal doesn't
work at all can persuade things to work for a while, so this might
suggest a loose or corroded connection?

The buzzing noise is very distinct, not a burning or shorting out kind
of noise, more an electro/mechanical thing. Could that be a relay
fault?

I'm going to get out my Haynes manual in a bit and go play with it
some more, but was hoping someone here might have some knowledge or
advice that might point me in the right direction.

Thanks very much if you can help....

"Bob"

 

[Mr. V]

I have a 1991 740 which has just developed an indicator (turn signal)
fault.

The problem began recently as a grumbling buzzing noise, sounding in
time with the blinking of the indicator light. The signal now also
intermittently cuts out and does not work at all. This also affects
the seat belt not deployed dash signal, which seems to be on the same
circuit.

I've had a look at the fuse behind the ashtray and it is fine, but the
buzzing noise can definitely be heard from the fuse box area now the
front cover is off.

I found that wiggling the whole fuse box when the turn signal doesn't
work at all can persuade things to work for a while, so this might
suggest a loose or corroded connection?

The buzzing noise is very distinct, not a burning or shorting out kind
of noise, more an electro/mechanical thing. Could that be a relay
fault?

I'm going to get out my Haynes manual in a bit and go play with it
some more, but was hoping someone here might have some knowledge or
advice that might point me in the right direction.

Thanks very much if you can help....

"Bob"

 

[Mr. V]

Check the Flasher relay, which should be in the middle position of the
second row of relays.

Perhaps the connection is oxidized: a blast of Electronic Cleaner
aerosol might solve that.

Or the Flasher itself could have gone bad: easy to source another from
a wrecking yard.

Helpful link: http://www.swedishbricks.net/700900FAQ/Electrical-CircuitsRelays1.html#Relay Locations