1987 740 gle electrical problem?

hi,

again, i turn to this extrememly helpful forum for help. it's a doozie...

just last night, i noticed that the bulb light came in my dash. it only
used to come on when i hit the brakes (the third brake light on the rear
window doesn't work). it the right rear tail light as well as the
right front orange light isn't on (and one of the rear licence plate
light). the light bulbs are fine. i checked the fuse under the ashtray
(strange place to put a fuse box, but i digress...) and the
corresponding fuse was blown. i changed it, and the new one blew
immediately.

now, isn't it strange that the left side of the car functions without
the fuse? or maybe left and right ones are on a different fuse, but i
couldn't decipher the fuse box. the blinkers work fine.

does anyone know what might be going on? i think there is a short
somewhere, but why only the right side?

confused,
jun

 

It sounds like the bulb failure sensor itself has failed, it's pretty
common for the solder joints to crack in here just like happens in the
fuel pump and overdrive relays. Thankfully it's pretty easy to repair
them as new sensors are $$$.

 

Left and right are on different fuses. Disconnect the wires from the
taillight and see if a new fuse blows. Then do the same for the front
light. If the fuse continues to blow with both disconnected, then you
need to start searching the wiring for a short. Pulling the bulb
failure sensor will remove the wiring to the taillight from the circuit,
so that would be a good place to start. Note there are 3 wires for
running lights going to the taillights. One is for the left, a second
does the right, and the third does the small side lights in the tail
lights and the license lights. The first 2 go through the bulb failure
relay, the 3rd does not. However the 3rd wire shares a fuse with one of
the tail light wires, so there's only 2 fuses.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)