Trans Solenoid Blows EEC fuse

[Telebend]

1992 Explorer 4x4
The EEC fuse blows unless the small connector on the driver's side of the trans just above the pan is unplugged. How do I determine which solenoid is the culprit? If I have to replace the solenoid(s), is there anything else I should do while in there? Could it be something other than the solenoid(s)? The truck has almost 300k on it, 2 tranny rebuilds so far, and a new fuel pump, but runs fairly well until this.

any suggestions? this newbie would appreciate it!

 

[MrShorty]

How do I determine which solenoid is the culprit?

I'd probably start by using an ohmmeter to see which circuit is grounding to the case.

Could it be something other than the solenoid(s)?

Possibly the wire(s) between the connector and the solenoids.

 

[Maniak]

My guess is the harness fell against the manifold and has melted. Its somewhat common.

You can manually check those wires by using a DVM and make sure your getting 25-40 ohms on the solenoids themselves (through the wire of course).

~Mark

 

[Telebend]

Thanks for the input!
I plan on doing some testing tommorow night. Will I be able to get to the solenoids/wiring once I drop the pan? I have read that the VB will have to be removed to replace the solenoids, but can you test them without removing the vb?

 

[Maniak]

I would try testing the following way.

Find the harness for the 3/4 and od and follow it up to the drivers fender. There is a plug on the harness there. Disconnect it. Now using a dvm measure the impedence between the redwire and each of the other 2 wires. That wiil test the wire and the solenoids. Also check between each wire and ground (looking for a short).

My guess is you will show a short between one of the solenoid wires and ground.

If so, disconnect the harness from the side if the trans. If the short goesaway take a good look at the connector at the trans and make sure the damage isnt there. If you find no external damage then you need to drop the trans so you can see (cant replace) the solenoids and the wires.

If possible, test for the shorts now. You should be and to find which has the issue amd my guess is a wire is frayed and shorting to ground in the pan.

If a solenoid needs to be changed the vb does come down.


~Mark

 

[Telebend]

quick update

I had just a few minutes this afternoon to look at it, so I pulled the connector on the driver's fender you mentioned. ALL of the wires checked as shorted to ground. The harness did not look to be against the exhaust or anything. I moved the harness around and the meter reading never changed. Hopefully I can pull the pan tommorow and look around.

 

[BrooklynBay]

It's usually the internal wiring harness. The insulation falls apart, and shorts against the case or the pan.

 

[Telebend]

Good info...I hope that is the problem. Is that harness available, or do you just repair with electrical tape?

I will post an update once I pull the pan.

 

[BrooklynBay]

WWW.TransmissionPartsUSA.Com sells it. Don't bother taping it since it will come off as soon as it gets sumbmerged in hot transmission fluid. It might be possible to use heat shrink tubing for a temporary repair.

 

[Telebend]

Bad News!

Pulled the pan and found the terminal on one of the solenoids completely burnt off. Any idea what caused this? What do I do from here? I know I need to replace this solenoid, but should I change both of them? Do I need to make any changes or upgrades while I have the vb down. I have never pulled a VB, but I am sure instructions are available on this site. Do you have any recommendations where to order the parts?

Thanks,

Hopefully these pictures show up.

 

[Telebend]

Update...VB done, but no OD

I have rebuilt the VB using the Transgo Kit, Replaced both solenoids, and other various things. It seems to run and shift fine except i have no Over Drive. Since the 3-4 Solenoid was the one that had burnt, it makes me wonder if I had OD before I started or not. This is my teenaged son's car, so I don't know if he would have noticed the lack of OD just driving back and forth to school.

I don't know if something I did during the VB rebuild caused it, or if it had already failed. Any suggestions on where to go from here?

As a side note, I used the "Firm" setting for the the drill sizes, and the shifts are definitely not harsh.

Thanks!

 

[MrShorty]

Because the 3-4 shift is electronically controlled, I'd start by checking the wiring and and electronic controls to see if the signal to command the shift is getting to the transmission.

1) Pull codes from the computer. Some faults in the engine management system will cuse the computer to not command the upshift.

2) The 3-4 shift solenoid circuit is a pretty basic DC circuit, so it is pretty easy to check with a voltmeter and a wiring diagram. See if the trans connector has power with the key on. Use the output state test (see my notes on pulling EEC-IV codes thread) to see if the computer can command the upshift. During a test drive, see if the computer is choosing to command the upshift.

 

[Telebend]

Problem Resolved -A simple fix!

I had forgotten that I unplugged the solenoid harness at the wheelwell during initial troubleshooting. Plugged it back in, and "viola" I have overdrive again!

Thanks to all on this forum who offered advice!

PS. I ended up not using the internal solenoid harness (23389B A4LD Transmission case connector 3 Prong 1989-94) $34.79 from Transmission PartsUSA. I did open it, but didn't use it. If anyone on the forum needs or wants it, Just send me a PM with a reasonable offer, and it's yours.

 

[BrooklynBay]

Thanks for the update!

 

[Maniak]

Woohoo... Glad to hear its up and running....

What did you use instead of the internal trans harness to fix the shorts?

~Mark

 

[jake122288]

hey im having a siilar issue with my 94 Ex. the eec fuse blew and i traced it to the plug where it goes into the trans... (its shorting internaly within the trans with the plug unplugged it works fine).... could this be a reason for not getting any forward gears?

 

[jake122288]

hey i pulled the pan off and sure enough my 3-4 shift looks just like yours did... burnt! so i found my short and i have one already but what do i need to change this... is it just the part or will i need a vb gasket (upper lower or both) is there anything else i should check for beings my truck lost drive all together when this issue occured... any help is fine sorry if im hijacking this thread im just lost and looking for input..

 

[Telebend]

3-4 solenoid

I believe the 3-4 solenoid was what fixed mine. The terminal broke/burnt off the solenoid. I was able to get the remnants out of the harness connector and clean it up. My plans were to replace the harness anyway, but with the trans in the car, it looked very difficult to get to the snap ring that holds it in. Since my harness was OK, I elected not to go through the trouble to replace it.

While I had the valve body out, I did a rebuild based on the excellent "rebuild diaries" on this site. I ordered everything but trans fluid and torque wrench from TransmissionPartsUSA, and it arrived quickly. The cost of everything minus fluid, torque wrench etc. came to $186.13. The wrench came from Harbor Freight. To save money, (assuming your harness is ok) you could probably just replace the solenoids $34, and filter and gaskets $14 and be ok.
If you need the harness, just let me know. It was $34.79 new, I will let it go for less if you need it

Good Luck

 

[jake122288]

I believe the 3-4 solenoid was what fixed mine. The terminal broke/burnt off the solenoid. I was able to get the remnants out of the harness connector and clean it up. My plans were to replace the harness anyway, but with the trans in the car, it looked very difficult to get to the snap ring that holds it in. Since my harness was OK, I elected not to go through the trouble to replace it.

While I had the valve body out, I did a rebuild based on the excellent "rebuild diaries" on this site. I ordered everything but trans fluid and torque wrench from TransmissionPartsUSA, and it arrived quickly. The cost of everything minus fluid, torque wrench etc. came to $186.13. The wrench came from Harbor Freight. To save money, (assuming your harness is ok) you could probably just replace the solenoids $34, and filter and gaskets $14 and be ok.
If you need the harness, just let me know. It was $34.79 new, I will let it go for less if you need it

my harness is fine also... i found the short tho too one of the wires that went form the tcc solenoid to the 3-4 shift solenoid almost all of the insulation was missing thus grounding out... so i just cut it out and crimped in a new chunk of wire and covered it in heat shrink tubing (around the crimp) havent tested it out yet due to not pulling the vb off to change the solenoid. what trans issues were you having with this problem? did you lose all drive gears or just crazy shifting? my filter doesnt even have 100 miles on it yet so i feel i should be good without changing it. what gaskets for the vb will i need? i think i may wanna look into a shift kit while i have it apart but i do not wanna put a bunch of money into it if the trans is shot (since i lost all forward gears, reverse works great tho)

 

[Telebend]

My trans was shifting fine, the car just shutoff going down the road, and had to tow it home. This was due to the blown fuse. With the help of this forum, I found the burnt solenoid, and "the rest is history".

It seems you may have other issues as well....