Fox T-Bird/Cougar Forums

Ok electrical guys i have a big issue with an Explorer...

1998 Explorer V6 OHC

Issue Fuse #13 blows. With this the truck has no battery feed to the Tranny computer and the Oxygen sensors heater circuits. Also the cam sensors and EVAP solenoid and a bunch more obd 2 sensors. The truck is stuck in fail safe which means it starts out in Third gear. The SES light is on and i have 10 Codes. replaced fuse number 13 and all is fixed. BUT do i release the vehicle to the customer??? Why did the fuse blow and why is it holding now??? So please chime in and should i take the chance of delivering the car. I say flat out NO. But the truck has been working fine for a week. I have been driving it all week and it is good so far. Please chime in. I can use some advice!!!. I am thinking of breaking down the circuits and separating them in half. But where to do this is my problem. So a look at all data shows several points and splices in the system but what a job to accomplish this. The fuse just has to many things hooked up to it to trouble shoot. So how to isolate lets say the O2 HEATERS ETC. Thanks

When and what cirspoogestances did it blow? Sitting still, going down the road, hitting a bump, etc?

Good question!!! The owner was on her way home when the truck acted up. She was able to drive it to the shop. I think i hit every pot hole in the state to make it happen again. Thanks for asking that. Any ideas??? I am on the fence on this one!!!

List out the codes and VIN, I'll run them on PTS, and see if any flag TSB's.

Turns out F1.13 feeds TCC, EPC and SS 1-4. It feeds the hego heaters, too, but I wouldn't consider the heaters to have a high likelihood of a short to ground. Also the CVV, but I'd unplug it if the open event recurs, codes can be cleared too easily to worry about setting them.  I'd split the circuit at C118 near the front of the intake, just pull a pin out and feed it alternative fused power from down circuit of the PCM power relay.  Then you can see which fuse blows; f1.13, or the inline powering the trans and cat monitors.

I'd look at the wiring harnesses to the O2 sensors to make sure they haven't burned against the hot exhaust, and also check the one near the front driveshaft to make sure it's not touching the driveshaft

That's what I was thinking too.

FOE thank you and i will supply the VIN when i get it Monday morning. What about separating the circuits at the fuse panel. All Data shows 2 wire feeds from CKT fuse number 13. But you idea ias very good as i am going to split off the circuits. By the way to date the fuse is holding. What a pain in the tail this is!!!!! By the way do you think this fuse is overloiaded??? I think it is. It is only 15 AMPS. THOUGHTS!!!!

The only thing on the one side of the fork is the CVV, and as I said above, it's unlikely.  So unlikely, that I recommended that if it came to it, to disconnect to rule out component. That circuit leg is already isolated. If you want to, you can fuse it separately too, or at least while in diag.

Its possible that the item responsible for blowing the fuse also fried itself, in the process becoming a harmless open circuit.

Correct but the car runs PERFECT. What could have fried????

Connected to this fuse as follows


4 heated O2 sensors

EGR Vac sensor

EVR sol

Cam Poditioner

Canister purge

Automatic TRANNY ECM

WOW which one is the culprit!!!!!

The trans doesn't have it's own ECM.  It's operated by the PCM, same as the engine. What IS powered on this circuit and related to the trans is the Torque Converter Clutch solenoid, the Electronic Pressure Control solenoid, and Shift Solenoids 1 through 4.

Bryan's thoughts are what mine were but the fault should now be a code unless for some reason it does not show up,, the possibility of this being likely is very low.

ask your customer if there was a visit to a car wash during the day the car acted up or perpaps the day before~especially if the car wash is near by the owners house and water was still sitting in places and did not evaporate off ,, or soap sudes ect.

Sometimes, this stuff might require a couple fuses to below before you decide to interrupt more downstream connectors or circuits all for the the sake of getting to the root cause and speculatory exploration.  I have broken more stuff during my "speculatory exploration" than i care to count and it kinda  me off.
Perhaps inserting a circuit breaker fuse in place of the fuse will help you troubleshoot?
As your reintroduce individual branches at the connector, the circuit breaker will then open.  The problem with this is that its somewhat intermittant now and no signs of showing itself anytime soon.
Drive the car in manual first , second, third ect and let the rpms come up to simulate shift solenoid loads for as long as you like ~not saying shift solenoids are the issue, its more likely something  you may recall being "FM"~ f'ing magic!


My advice word for word to the customer~
"Ok, I have found a blown fuse which i replaced however, i want to know why it blew.  I have examined the wiring diagrams and performed a visual inspection for any wiring problems and havent located any issues.  I would like to know why this happened but for the past week all has been well with the truck and the fuse is holding.  I would suggest you operate your car as normal and if for some reason it acts up again, this will tell us both that the problem is much deeper and will require my full attention.  Right now I am speculating on what could have caused this fuse to blow in the first place.  There is an old saying ~ if it aint broke, dont fix it."

It feeds SR55E. This is some sort of tranny computer or Gem module. Reason being i got 6 transmission codes when the fuse blew.

5R55E is the transmission itself. You got 6 trans codes from the PCM, because you would have had 6 solenoids without power.

Hopefully that diagram will explain the transmission controls a bit better, and where the 6 codes came from.

MAN do i hate AUTO TRANNYS. They suck big time. Well not really. yes those are the codes i had. So once again holding for over a week now. The ford dealer advised me to install a 20A fuse. They said this fixes it. But why????? The truck has 120 on the speedo and runs perfectly and shifts like a dream. I hate these troubles with a passion. If the short was hard it would be easy. BUT NO THE MF has to be intermittent. Well i am so greatful for all your guys for posting. Foe i think at this point i will never find out what happened. Do you think the circuit is overloaded??? I cant see why as ford designed it this way. But one never knows. I am thinking the tranny solenoids are the issue but not 100% as the dam car is still running GREAT!!!  What a headache!!!! I was thinking of separating the tranny from the circuit. Thoughts!!!!

Thanks Foe those tranny prints are great. As you can see i have no clue when an AUTO TRANNY is involved.

have you checked condition of all your ground connections?

Unless you want to end up mired in Pinpoint Z, you might as well return to customer, and monitor the situation.  I'm sure you've got other vehicles to attend to.

+1    I've had fuses blow a couple of times over the years where I replaced the fuse and never had the problem again.

I got it Bryan but if it blows the car is going to run like real bad and the women might PANIC. I an trying to figure out how a fuse blows for no apparent reason and then holds after replacement. It makes no sense. Fuses do not blow for no reason. Just saying. But i am thinking you may be correct but WHY!!!!

Your Dungeon awaits you, sir.



Pinpoint Z is the worst thing in the world, but it usually finds your problem.

Thanks foe i can see you have been down this road once or twice. You sir feel my pain. But you were very helpful to me as i did not know that SR55E thing was the valve body solenoids. I hate auto trannys and you helped me a lot. Thanks FOE. Now once again i will try and break down the circuits to smaller groups. Thanks!!

I made it all the way through Z once.  It was horrible.  Now I spend my hour and If I can't get it to act up, I explain it to the customer and ship it.  Sounds bad, but I can't lose like that on a regular basis and still make a living.

Once again, I'd be checking the wiring to those o2's, making sure they didn't burn on the exhaust or wear against the front driveshaft, especially where the harness follows the cross member. This is most likely your problem. I'd also check the O2's themselves, to make sure the body of them isn't broken (common in rusty areas where the body of the sensor rusts and breaks).

Will do thunder Thanks!!