I gotta 2000 F350 Dually 7.3l. A few months ago the truck didn't want to start and I kept having to jump start it as the batteries would seem to go dead after a day or so of sitting so I took the truck to Autozone and they said the batteries were junk. I bought new batteries and after a few days it started going dead again. I was thinking I had a parasitic drain somewhere so I hooked up my meter and it showed a .16 amp draw. I started pulling fuses until I found the GEM fuse to bring it down to zero. Everything I've read leads me to believe I may have a bad GEM unit but I need to be sure before I drop $350 on one. My passenger window is slow to go up or down and power locks click but don't actually lock or unlock.

Where I'm confused is that I took the batteries back into the store and had them checked to be sure they were good, they checked good and charged them up. I put them back in the truck, inserted the key and waited for the "wait to start" light to go out. It turned over good and fast but wouldn't start. I did hear a clicking noise while it was cranking (possibly a relay) coming from the drivers interior fuse panel. I let it sit for a minute, put the key in and immediately cranked it without waiting for "wait to start" light to go out. The truck started right up. This has become an everyday issue. The truck cranks decent but wont start and I hear the clicking noise by the fuse panel. If I cant get it to fire up by just putting the key in and cranking it, I have to jump start it with another vehicle. If I jump it, it starts up like normal. What other checks can I perform?

 

forgot to add that once the truck runs for a bit it will start just fine, if it sits for a half a day or more it doesn't want to start.

 

Try and measure your voltage when starting... it may be a voltage drop due to corroded or bad cables or possibly the starter "dragging" your IDM needs to see 10.5 volts minimum to start the truck

 

battery voltage is 12.6V right now. Trucks starts great right now as I just got home from a 45 min drive. Volt gage on the dash is showing over half (13-ish I guess). When I tried to start it to come home it showed just under half on the gage, it cranked over fine but clicked a little bit then started. Alt shows good voltage on the dash panel when driving and batteries show over 13V when truck is running so alternater seems good. whats the best way to check voltage drop when starting? Through the cig lighter?

 

checked voltage through cig lighter while starting. Voltage dropped to 8.5 and truck started. Did this 3 times, same each time.

 

Check it tomorrow when the truck is cold.. How is the oil? Fresh and full? Dirty and or low oil can make for hard starts too whereas we rely on high pressure oil to fire our injectors

 

oil is good

 

since last post (30 mins) I watched the game for a bit and went back out. Voltage on batteries are 12V and 12.6V so the drivers side dropped .5V. Gage on dash is well below 1/2 on the scale now and truck cranks but wont start. Clicking noise is coming from under the steering column and not from the fuse panel.

 

the battery that has only 12v needs charged & tested its dead as that voltage.

 

Did you measure the voltage on each battery while they were connected or did you disconnect them to take the readings? If you measured the voltage while they were connected, your batteries should not show a half volt difference between the driver and passenger side, regardless of charge. They are connected in parallel with heavy cables and should read the same voltage. Double check your cables (positive and ground) for clean, tight connections at each end.

Clicking noises coming from the dash usually mean low voltage while cranking. This also points to posible loose or corroded battery cables.

 

good call on the batteries. All connections are clean and tight. A friend suggested looking at the glow plug relay incase it was stuck closed causing the glow plugs to heat continuously. GPR seems good as it clicked off after about 30 seconds and voltage went dead on glow plug output wire. Truck wouldn't start until I jumped it with our other truck.

 

Ran truck for 30 mins after jumping it last night. This morning batteries had 12.4V and 12.6V. Truck cranked but wouldnt start. Jumped driver battery to passenger battery - no start. Now cranking slower and slower. Jumped from other truck and it started. Runs and drives fine once started. No smoke on start up. Cant stand this anymore. Every morning in this rain.

 

There are two ends to every cable. This sounds like the other end of each battery cable needs a visit. 12.5 V until you turn the key - then 8 V? Connection - or really bad Glow Plug circuit is suspect. One really remote possibility is the trailer wiring or relay. Very few things on the truck can suck the juice that hard when you turn the key... at least without catching fire. Smoke signals have one advantage - you know where the problem is.

 

did you check the grounds where the bolt to the block. i had same issue last winter, driver's battery had loose connection at the block causing intermittent surface charge that would dwindle over night. i would drive the truck normally then disconnect both batteries over night, then before you reattach them check voltages, if one is low compared to the other then you have a direction to go. get that one rechecked, and recheck connections.

another way to test for bad connections is to use a V.O.M. and check voltage with truck running. connect negative lead to battery POST, and positive to battery POST, then move + to batter clamp and see if there is a difference, then leave + on battery clamp and move - to battery clamp see if there is a difference, then move - to other battery or a good ground on the block. do this to both batteries, this will help determine if you have a poor connection or cable, it helps if while testing you try to move cables and see if readings change.

 

did you check the grounds where the bolt to the block. i had same issue last winter, driver's battery had loose connection at the block causing intermittent surface charge that would dwindle over night. i would drive the truck normally then disconnect both batteries over night, then before you reattach them check voltages, if one is low compared to the other then you have a direction to go. get that one rechecked, and recheck connections.

another way to test for bad connections is to use a V.O.M. and check voltage with truck running. connect negative lead to battery POST, and positive to battery POST, then move + to batter clamp and see if there is a difference, then leave + on battery clamp and move - to battery clamp see if there is a difference, then move - to other battery or a good ground on the block. do this to both batteries, this will help determine if you have a poor connection or cable, it helps if while testing you try to move cables and see if readings change.