Lucky #13 fuse in the battery junction box keeps blowing.

I had this problem about 4000 miles ago. When the fuse goes, I get 7 transmission fault codes. I replace the EPC and all has been well. I just popped the blasted fuse again. Now I have 12 codes including o2 sensors, cam position sensor, and canister vent solenoid failures.

Ford has put way too many circuits on this little 15 amp fuse. I have started to check wiring for shorts and "green death" but havn't found anything yet. Has any one else had this issue or any thoughts on which circuit is the culprit ??

Thanks for any and all imput !

 

check for burnt harness over the trans back of the engine???

 

I am doing "pin point" tests now. I have determined that I do have a short to ground but have yet not found it. Is that part of the harness a "problem child" ??

Thanks, Mark

 

can be if someone has been in there before and not put the wires back in there retainers

 

It dosn't look like the harness has been tampered with. I have ruled out the canister vent solinoid circut. The EVR wiring is OK. The only thing left is all 4, o2 sensors, the EPC and all the shift solinoids, and of coarse the wiring in between.

Any body know of tests for the trans solinoids?

I just ordered the Auto Enginuity scan tool with enhanced Ford program. Hopefully I will be able to see the solinoids working......or not.

 

The scan tool is not in yet............

I cannot find any shorts in the wiring harnesses. If a shift solinoid or HO2S goes bad, could it cause a short to blow a fuse ???

Thanks for any and all help!

 

Yes they could cause a short. Does the short happen as soon as you replace the fuse or is it intermittant?????

 

there should be a splice running fromc118 that is lb/og wire with about 6 wires in it. If you could find it you could put inline fuse in each line to help find which circuit has the short. c 118 should be about the centre of the engine may be in the area of the pcm and should be a 16 pin square connector you would have to open this harness up to find the splice. You may want to disconnect each o2 sensor and the canister vent value and the egr solinoid one at a time to see if your short goes away. I know it is very hard to find but the most common area of a problem is around the trans and back of the engine and exshaut pipe. good luck

 

I have C118 apart and the the short harness from C118 out of the truck. I have put a ohm meter to all pins and have found nothing.

I have put in line fuses into the LB/OG wires coming off the battery box. After about 5 miles, the fuse pops for the o2's and trans solinoids.

By watching the live data on the scan tool, should'nt I be able to see what sensor or at least circuit has failed?

 

the front left, rear right and left sides o2, and the transmission has 3 wires going to it they are all down stream of c118 as is spilce 179. sound like you eliminated everything upstream of c 118. so next i would find spice 179 and fuse each circiut in it. Or try driveing the truck with all the o2 disconected except the right frt o2. if the fuse still blows you will have norrowed it down. The right front o2 in the book is powered upstrean of the c118 good luck

 

I can see S179.............This location is worse than the spark plugs!

Short of pulling the intake, how the heck do you get to it?

 

Hey, wait a minute...............S179 is in the harness I have out. I need another cup of coffee. I'll splice them in and keep you posted.

Thanks!

 

I have put 4 inline 15 amp fuses into the harness. One for all 3 HO2 sensors and one for each of the transmission circuits. I have driven it now 60 miles and all the fuses are still alive. Is it possible that with all these fuses I now have, I could be hiding the problem since the amp draw is now seperated into each circuit ??? Should I be using a lower amp fuse ???

Thnaks for any and all help!

 

any thing is possible but I suspect that somewhere along the way you have moved your problem away from ground and may never return. I have had this happen and the customer return couple years later and say never had another problem.