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Jim Grant's Tech Tips
Hot
Diagnostics
Q:
Can you help me troubleshoot my problem. A few days ago I lost the tail
lights in my van. I thought I could smell something burning. Also the
dash lights are out. I checked the fuse and it was spent. I replaced it
with a new 15 amp fuse and it burnt right away. I went to 20 then 30,
both burnt. I bypassed the fuse and started getting smoke (not too smart,
huh). My brake lights work, my directionals work, but no my emergency
or tail lights. I would appreciate any constructive advice rather than
the obvious of going to see a tech.
A: Bypassing
the fuse with a jumper is a sure fire way to get things smoking. You're
likely to do more damage than good using that approach to identify the
problem. Whenever a sudden electrical problem appears, the first question
I ask is: what has been worked on recently? Has there been any body work
or accessory upgrades such as a radio? A wire can be damaged during these
procedures and become a problem a short time later. If I'm not mistaken
you have problems with three different electrical circuits. The dash lights
use a different fuse than the tail lights and the emergency flasher is
another circuit in itself. The ideal approach would be to obtain a wiring
diagram and start tracing the wires from the fuse panel to the first connector
and disconnect it, then install a new fuse. If the fuse doesn't fail then
you know that part of the wiring is good. Then move to the next wiring
harness connector of that circuit and repeat the procedure. A good wiring
diagram, patience and time is needed to diagnose a problem like yours.
If you still come up short, take your car to a qualified tech.
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