Ambear136

I am trying to help my husband figure out what is going on with his truck. He is gone to the field for a week so I am trying to help him out and fix some things. First if all he just bought a 98 f150 4x4 . We took it straight to dealership because the tires were bad. They told us the fuse box needed replacing and the hoses . I guess the truck was sitting for a while. Well they wanted to charge us over 3 grand to fix everything. My husband bought a new fuse box and gem module and replaced those. Here are the issues... Truck wouldn't crank at first without being jumped. ( before replaced fusebox an gem ) after truck ran a couple of days now it won't even turn over. Won't start w a jump or anything. Key in ignition lights come on on the door but intermittently. Can anyone help me figure out what is wrong?

par_124

How soon after the purchase did these troubles begin? Did it have starting problems when test driving and inspection? Surely it didnt come out of the blue as soon as u bought it or has it been a while?

( if it already had starting problems before transfer of ownership) The person who would know the most is the previous owner. If u bought it from a reasonable individual they may not mind a quick phone call to give u a head start on diagnosing the actual cause.

If u got it from a dealership then hopefully its still under a 30 day warranty in which case they should definately attempt to fix it.

mawk

Plug the original GEM back in. If it works, use it or purchase from the dealer. They're not interchangable across the board. Double check the fuse block, as it may have a faulty connection.

Ambear136

Thank you for the advice. I ended up spending all day cleaning the connections and cables for the battery and it is starting. The heat doesn't work so I spent all day today flushing and drain and more flushing until the water was pretty clear . Still no heat but I believe it is the control button. Any ideas? The hoses are both hot to the touch so I believe the heater core is working .

Sappy72

My heater control is like that. If I put it at 100% heat, it goes cold, so I have to put keep it at 90-95% of the ****.
I'll eventually get around to replacing the module, but don't feel like shelling out $25+ for it right now.

Frank_Ford

Sounds like you are doing real good without my help or the help of anyone else. The most common reason for no heat is low on fluid. I trust you changed out the hoses when you did the flush. I also understand that both of the hoses to the heater core are hot which would indicate that the circulation is good through the heater core. However, a test of the water pump given the previous condition of your cooling system is no cost, easy and narrow down the problems. First make sure your fluid is full. When you flushed your system you may have left a bubble in the system when adding fluid so make sure your fluid level is full. To test your water pump , pinch top radiator hose with engine idling. Release hose and feel for surge of fluid in the hose that would indicate good water pump. What happens with the water pumps is that they rust if not maintained and impeller blades disintegrate and the water cannot circulate properly through the engine and especially through the heater core.

The rest of the heat system works by mixing outside air through duct work and through the heater core. If these doors in the duct work are not operating properly you won't get heat. However, fixing these is out of my pay grade and I cannot help you much. I understand they work by vacuum lines so if it was me, I would listen to see if I could hear them working. If not, check the vacuum lines under the dash. Then if I still can't find the problem, I would take it to Joe Malcolm's garage along with my check book.

Warspite

+1. Check the vacuum lines near near the firewall, battery side. They're plastic, and can go brittle, and poof! Are you able to direct the air from floor to panel to windshield with the switch? If not, then those vacuum lines are the problem, most of the time.