Hey all , I'm new to this group and am hoping I can get some advice/info ! My husband has a 99 F150 with the Triton engine . For about 5 years now it decides to go dead whenever it wants to . Today I hooked it up to the battery charger and let it sit for about 2 hours . Went out to start it and the blower motor was running full blast , so I hopped in the truck and shut it off . The keys were NOT in the ignition . I then let it charge for an hour , went outside and it was trying to start itself over and over again ( never had enough juice but just enough to try from the charger ) . The ignition was replaced by the dealer this summer , so I know it's nothing to do with that . Anyone have any ideas ? I really don't want to call a tow truck to drive it 25 miles to the dealership where they will charge me an ungodly rate ! Thanks in advance !

 

It sounds like you have a HEAVY parasitic current draw issue. Parasitic draw is the drain on the battery from things like the radio's memory that ALWAYS use power. To measure the current draw, pull one cable off of the battery and connect a multimeter between the cable and battery. It doesn't really matter which cable you do this on, it works the same either way. For my 97 Expedition, I use the Negative cable, while my 1987 RX-7 is tested with the positive cable.

Parasitic Draw should be approximately 50 mA. If it reads more, pull one fuse at a time to identify which circuits are draining the battery excessively. Having long meter leads with alligator clips really helps with this. Please note that most average multimeters are limited to 10A, so don't try starting the engine while measuring current draw. I did it once years ago and caught the meter on fire. It still works though

Just to confirm, which was replaced by the dealer over the summer: The ignition switch or the ignition coils? IIRC, the blower is an ignition-switched circuit, so it leads me to believe that the ignition switch was either defective or incorrectly wired. Logically, the blower behavior you've experienced could also be seen on other ignition-switched circuits like the radio. Try turning it on with the key OFF or not in the ignition. If it can be turned on, the ignition switch is suspect.

 

Thank you Travis S , I will try that . The dealer replaced the ignition switch ( tumbler ) because the security light was on constantly ( it had been replaced before , but not with Ford factory parts ) . I have the battery disconnected right now and need to charge it ( it was trying to start every 20 seconds when I had it hooked up to the charger ) . No worries on the meter , I'm an electrician so having a heavy duty meter is kind of a must for my job ! Thanks again , hopefully I can get it figured out ! I forgot to mention that all 8 of the ignition coils have been replaced over the last 3 years ......

 

Thanks for joining

Tony