740 turn signal problem - buzzing noise, relay issue?

Jul 26, 2007 2 Replies

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"


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:

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