Big HEADACHE !!!!!

Topic: Big HEADACHE !!!!! (Read 1740 times) previous topic - next topic

Big HEADACHE !!!!!

April 06, 2013, 08:34:03 PM

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

Big HEADACHE !!!!!

Reply #1 – April 06, 2013, 09:29:47 PM

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

Big HEADACHE !!!!!

Reply #2 – April 06, 2013, 10:28:13 PM

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!!!

Big HEADACHE !!!!!

Reply #3 – April 06, 2013, 10:41:59 PM

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

Big HEADACHE !!!!!

Reply #4 – April 06, 2013, 11:06:12 PM

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.

Big HEADACHE !!!!!

Reply #5 – April 07, 2013, 06:51:06 AM

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

Big HEADACHE !!!!!

Reply #6 – April 07, 2013, 08:41:55 AM

Quote from: Thunder Chicken;412768

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.

Big HEADACHE !!!!!

Reply #7 – April 07, 2013, 07:52:28 PM

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!!!!

Big HEADACHE !!!!!

Reply #8 – April 07, 2013, 08:38:08 PM

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.

Big HEADACHE !!!!!

Reply #9 – April 08, 2013, 01:18:34 AM

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

Big HEADACHE !!!!!

Reply #10 – April 08, 2013, 05:36:07 AM

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!!!!!

Big HEADACHE !!!!!

Reply #11 – April 08, 2013, 06:31:02 AM

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.

Big HEADACHE !!!!!

Reply #12 – April 08, 2013, 09:48:04 AM

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."

Big HEADACHE !!!!!

Reply #13 – April 08, 2013, 12:24:56 PM

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

Big HEADACHE !!!!!

Reply #14 – April 08, 2013, 12:31:27 PM

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