RAM 2500 Truck 2WD L6-5.9L DSL Turbo VIN 7 (2001)
Ignition Off-Draw (IOD) Fuse: Description and Operation
Fig.3 Ignition-Off Draw Fuse
IOD FUSE
All vehicles are equipped with an Ignition-Off Draw (IOD) fuse (Fig. 3) that is disconnected within the Junction Block (JB) when the vehicle is
shipped from the factory. Dealer personnel are to reconnect the IOD fuse in the JB as part of the preparation procedures performed just prior to
new vehicle delivery.
The left end of the instrument panel cover has a snap-fit fuse access panel that can be removed to provide service access to the fuses in the JB. A
finger recess is molded into the access panel for easy removal. An adhesive-backed fuse layout map is secured to the instrument panel side of the
access panel to ensure proper fuse identification. The IOD fuse is a 10 ampere mini blade-type fuse. The fuse is secured within a black molded
plastic fuse holder and puller unit that serves both as a tool for disconnecting and reconnecting the fuse in its JB cavity, and as a fuse holder that
conveniently stores the fuse in the same JB cavity after it has been disconnected.
The term ignition-off draw identifies a normal condition where power is being drained from the battery with the ignition switch in the OFF
position. The IOD fuse feeds the memory and sleep mode functions for some of the electronic modules in the vehicle as well as various other
accessories that require battery current when the ignition switch is in the OFF position, including the clock. The only reason the IOD fuse is
disconnected is to reduce the normal IOD of the vehicle electrical system during new vehicle transportation and pre-delivery storage to reduce
battery depletion, while still allowing vehicle operation so that the vehicle can be loaded, unloaded and moved as needed by both vehicle
transportation company and dealer personnel.
The IOD fuse is disconnected from JB fuse cavity 12 when the vehicle is shipped from the assembly plant. Dealer personnel must reconnect the
IOD fuse when the vehicle is being prepared for delivery in order to restore full electrical system operation. Once the vehicle is prepared for
delivery, the IOD function of this fuse becomes transparent and the fuse that has been assigned the IOD designation becomes only another Fused
B(+) circuit fuse. The IOD fuse serves no useful purpose to the dealer technician in the service or diagnosis of any vehicle system or condition,
other than the same purpose as that of any other standard circuit protection device.
The IOD fuse can be used by the vehicle owner as a convenient means of reducing battery depletion when a vehicle is to be stored for periods not
to exceed about thirty days. However, it must be remembered that disconnecting the IOD fuse will not eliminate IOD, but only reduce this normal
condition. If a vehicle will be stored for more than about thirty days, the battery negative cable should be disconnected to eliminate normal IOD;
and, the battery should be tested and recharged at regular intervals during the vehicle storage period to prevent the battery from becoming
discharged or damaged. Refer to Battery for the location of additional service information covering the battery.
