Rear defog problem

[colinc]

Early 74 260z. Had the centre console off to replace shifter bushings which went well. I decided to tackle my rear defog problem. Last year it was intermittent at best (i.e. if I turned on switch the indicator light may or may not come on - I couldn't tell you if the defog grid worked as I didn't drive in conditions where it was required). Testing today showed power to the switch but intermittent power to light (I could here relay cutting in and out with switch). After messing with it for a bit I managed to get no power to switch -great!. The FSM shows a 10A fuse between the ignition and the defog switch (I assume in-line fuse). Does anyone know approximately where this fuse lies (note the 20A fuse in the fuse panel has power over it).

As a follow-up, if I manage to get power to the switch I will still have the intermittent power to the indicator light problem. What are the chances the relay has gone? (I have a replacment but it is very difficult to get at).

Thanks for the help.

Edited January 22, 2012 by colinc

[colinc]

Upon further review, it appears the 10A fuse is the same fuse that the radio uses??

[SteveJ]

Yes, the coil of the defroster relay is on the same fuse as the radio.

As for the relay failing, yes, the coil can fail. If you hear the relay clicking, that would support a coil getting weak before failing.

Don't forget to check the connectors for failure, too.

[colinc]

Yes, the coil of the defroster relay is on the same fuse as the radio.

As for the relay failing, yes, the coil can fail. If you hear the relay clicking, that would support a coil getting weak before failing.

Don't forget to check the connectors for failure, too.

Thanks for the reply. I hope it is just the fuse but the relay was definitely clicking. I will post results (probably a couple of weeks as the battery is off the car and back in the basement waiting for the next warm spell).