Dead Battery on Towed Vehicle
On our crab fishing trip in September 2000, one of the
towed vehicles in our group arrived at our destination with a dead battery.
It was a mystery as to why the battery ran down while the car was being towed.
To work around the problem, the battery cable was disconnected before towing
and reconnected when the use of the car was needed.
After arriving home from our trip I discovered a story on page 24 of the
September 2000 issue of the FMCA magazine. The story was about a 2000 Saturn
L-Series car that had a problem that may be common to other makes of automobiles.
It seems that the Saturn, being towed with four down, twice arrived at
its destination with a dead battery. When the car was serviced the second
time, the dealer had received a service bulletin covering just such a problem.
The Technical Information Bulletin tells the story, the solution provided
may not be elegant, but it is simple to achieve. When the ignition key is
turned to the "Accessory" position for towing, the Body Control
Module (BCM) can draw enough current from the battery to run it down. The
fix is to remove a couple of fuses. This disconnects the power to the BCM
So, if youve had a similar problem, you might find the answer at
you dealers service center. Better yet, the answer may be in the owner's
manual for some vehicles.