Indicator fuses intermittently blowing

[Selseymech]

Fuse blowing (intermittent or instant)

There have been many accounts on various sites regarding Defender indicator/stop light (15A) fuse blowing

 

This procedure was arrived at after several hours spent attempting to find out why both indicator and hazard fuses were blowing.

    The vehicle is an Ex Military Defender 1991.To avoid any confusion do check that the 6 way lighting switch is in the off position and for safety, disconnect the negative battery lead.

   It is important to understand the current path when :-

1/.A turn signal is requested.

    From the fuse (15A)the current flows through the hazard switch to the relay (Green/purple) up to the indicator stalk (Green/red) and thence to either the left or right 3 bulbs.

  The current drawn by the bulbs will be 

21+21+2=44watts which is 44/12=3.6A

2/.When hazards are turned on.

  From the hazard fuse (20A) (permanent 12V) current flows to the hazard switch thence to the relay and back through the hazard switch to both sets of indicator bulbs(Green/Red for LH and Green/White for RH) The current drawn by the bulbs in this case will be will be 2 x44 watts  therefore. 88watts and 7.2A well within the limitations of the relevant fuses.

      

Next steps are the easiest I found to eliminate the fault without unnecessarily disturbing the wiring harness.

1/.Access the hazard switch and unplug it

2/.Remove all 6 indicator bulbs

3/.Remove flasher relay

4/.Put multimeter ohms range on output pins of hazard plug, green/red for left green/white for right, check readings should be infinite.If any short circuits are found disconnect indicator stalk multi plug may have to remove steering wheel and cowling.

5/.If short circuit still present,isolate front and rear indicators by disconnecting the chassis/body multi plug in centre of engine compartment ( its the loom that runs through the right hand chassis).We now should have narrowed down the short to the wiring loom either front or rear on one side or the other.

 

The offending fuse can be replaced by a resettable fuse while live faultfinding/testing thereby saving a pile of open circuit fuses.

My fault turned out to be the indicator stalk intermittently short circuit and I was lucky enough to track it down in the fault condition because intermittent faults are the worse!!

Hope the above helps 

 

Good luck!

[Snagger]

Chafing damage and shorts are very common on the wiring under the front wings on all years of Defender, especially where they pass through brackets or fittings.