Hi,
Earlier this year, I had a fuse that kept blowing (heater/AC, cruise control, reverse lights), so I narrowed it down to the reverse lights - would blow every time I put it in reverse. But after about 4 or 5 fuse replacements, it just stopped blowing. Then everything worked fine for a few months, and now it's blowing again.

Not sure how I start to diagnose/fix whatever is going wrong in the reverse light wiring (any helpful hints appreciated), but does any one know why it blows intermittently? That seems odd to me.

Thanks for any info,
Kim

97 F150 Lariat shortbed flareside, 5.4 engine, 4WD

 

I would start up by the transmission.

The DTR switch is on the driver's side of the trans, and runs back in the same harness as the O2 sensor into the engine compartment.

You will see the trans case speed sensor and the hi/loo for the indicator on the cluster as well as the DTR. Last item prior to turning up into the engine compartment is the HO2Ss on that side.

Just had a thread not too long ago, where the wires ( as they turn up into the engine compartment by the xhst manifold ) where loose and got melted.

Just a thought on where to look first.

 

I would be suspicious of the tail light housings. You may have moisture collecting around the backup lamp sockets. When you have the problem, look for condensation or water in the housing where the backup lamps reside.

 

Because there's an intermittent short.