Hi ,
I have a 97 Expedition 4.6 4x4 that I've owned 10 years..no major problems until now. The truck sat for about a year ,and last month we put it on the road ,drove it 220 miles and it shuts off at 50 mph and the theft light began blinking rapidly,disconnected battery for a few minutes & it started a few miles later the same thing . Took off battery terminals and left it overnight ,next day it started &while running we took it to a Ford dealer and had second key made and old one + door remote reprogrammed ..after they ran diagnostics ,but couldn't pull a code.They said they hoped it was the key ,didn't charge me for diagnostics,because they said it wasn't what they had originally thought ,which they never said what that was .(leaky windshield syndrome?).I could have told them my windshield was replaced in 2000,when I bought it. Anyway drove another 300 miles it rained ..and it happened again,same as before and today no rain .Now it wont start ..only cranks &theft light is blinking rapidly .From reading other threads and posts ,I know its not the PATS(as did Ford) or it wouldn't have shut off while driving ,and that it could be PCM relay ..Here's the question.Where is the PCM relay? My owners manual and mitchel1 repair guide doesn't say. Is the EEC Power relay in the PDB it .I see the fuse marked PCM power relay #24 but not a relay.By the way all fuses that we can find are good ,but we found water in passenger side kickboard .Could that be related ? Only other electric problem is 4x4 will click in and out when engaged .Fuses and under driver side dash looks perfect no rust or water.Thanks in advance..
Loretta

 

It's in the fuse box under the hood, it's relay #6.

You can download a PDF copy of your owners manual here:
https://www.fleet.ford.com/maintenan...ls/default.asp

 

Thank You.I have a 98 owners manual and its marked EES in that one .I'm not familiar with anything electrical,but I'm learning as I go. This sight is great.I've seen that link in alot of posts,but didn't realize there would be a different name on the relay in a year later model..Appreciate your help.
Loretta

 

I would check the area around the passenger side of the windshield and under the hood as the PCM is located way up in the corner to the outside of the of the passenger side. To make sure the water is not getting to the PCM as that could cause a major expense.

 

Hi . The area around the PCM looks o.k. too.doesn't seem to have water there or traces of water,just under the trim of the floor boards in that channel inside the kick board on passenger side it doesn't seem to have come down the fender wall ,but lower, cant see any rust or traces of water around the computer, or whatever that is up under there.Hoping it's a relay ,because this morning after terminals were off all night ,it fired right up...Go figure.Another question can you switch the horn or washer relay to trouble shoot or should I just try a new one ? Could rain or moist air,like fog, affect a faulty relay and cause this type of problem.
Thanks...Loretta

 

Yes, if the relays are of the same value and the plug is the same. There should be some ID on the relay and if they are the same, no problem.
Rain and heavy fog can cause problems if the units affected are not properly sealed. The PCM slides through a hole in the firewall from near the right kick panel and the engine harness plug is exposed to any moisture that gets up and around the engine. There is only an 8 or 10 mm bolt that secures the plug to the PCM, there is a rubber seal built into the plug and I suggest that you or someone check it to be sure it is good and snug.
The water that you have found might be some overflow from the ac unit not draining out of the HVAC box. There must be a drain through the firewall or floor that could be clogged causing the water to be inside the cabin.

 

Actually it's marked EEC, which stands for Electronic Engine Controller. It's the same thing as a PCM but with a different name. I agree that they should label it ASD since most everyone is familiar with that term.

 

Yes EEC ,I got it right in the original post .So many abreviations ,and they are all new to me .I've got alot to learn about this vehicle.It's confusing trying to process this info overload.But I'm glad this sight exists.My car is getting old ,and I've never had to worry about fixing it but with everyones knowledge on these posts..i'm thinking we just might fix this thing yet.Without breaking the bank..(I hope!)
Thank You Again
Loretta

 

FIRST do you have the code for the door? Put the code in (original code). and then try to start the truck.

I had the same issue and the truck started with the original code.

 

If you don't have it it is on a box above the E-Brake under the dash.

 

Hi
I'm not sure what you mean by a code.As I said I took it to the dealer and had a second key and old one reprogrammed ,it's not the key.The dealer could not find any codes ,because it wasn't doing it at the time (so they said) and they told me they thought the key too.They never mentioned any concerns about water intrusion either and at the time i wasn't aware of that sort of problem on these vehicles.However they did give me an estimate of $2500 to replace both manifolds and either upper or lower ball joints ,I don't know which ,because they never gave me a copy of the estimate .I wasn't there for ball joints and wasn't paying attention .My concern was it shutting off at 50mph with no warning,and the PATS .I even asked if the key sent a continuios signal to the PCM and they told me yes,because It didn't make sense that it was the key ,if not. Now I know thats not true.
I actually stumbled across the fact it seems to happen after rain when it did it again about 2 or 3 hundred miles later .Thats when I found this sight,and began to look for water intrusion to Fuse box and such .We are starting with the PCM relay and waiting on the rain tomorrow ,if it does it again its not the relay ,then we will be looking at 02 sensors next .I'll keep everyone updated.
Thank you everyone for your input..Loretta
P.S. It could be tired it's got 220,000 miles and this is first major problem.

 

Here's a thought regarding your suspected water intrusion. Before it's too cold you could take your truck to a DIY car wash and have someone position themselves so they can see up under the dash with a strong flash light and look for any place that shows seepage or a leak. You could do much the same at home with a garden hose by spraying water at a high pressure on all of the suspected areas of water leaks.

 

Well it rained and when we started it ,and it fired up .Then we opened the hood and the engine started to stall and run really rough and die out ,then it recovered on its own ,and didn't trip the PATS it just shut off,but on second attempt to start it , it fired up and ran rough, straighted back up ran normal for 5 minutes ,then died and then the theft light came back on and it would only crank,and not start .So its not the relay ,but we are almost certain that water is dripping on to PCM via the plastic piece that is under hood and supposed to divert the water to the fender wall especially if you open the hood .Not sure how long this has been happening.So we need to inspect PCM.

Can we remove the bolt and pull the plug on PCM to inspect it?

We are going to reseal that plastic piece ,but the damage may already be done ,and may have to replace PCM
Thanks...Loretta

 

Hello again,
It turns out the bolt holding the plug that goes to the PCM was loose enough to remove by hand and after removing the PCM and looking there were a few drops of water and some dirt or residue to prove water had been there before .We lifted the blue rubber where the prongs or metal point things were ,just enough to see if there was moisture and there was .So we used a hair dryer to dry it out ,we also opened metal cover to see if water had gotten inside .It doesn't appear to have entered there.So after reinstalling it ,It started ran a minute and died ,and theft light came on,then after 8 or 9 attempts to start it,It fired right up and... without removing terminals (first time since this all started).All lights were normal and it ran smooth !
I'm really hoping no permanent damage is done to the PCM .So THANK YOU.. Moto Mel ..you were exactly right.
Amazing the havoc a few drops of water can cause!!
If problem returns we will replace PCM.I found one online at ALL COMPUTER RESOURCE.COM for $265 programmed and flashed .

WE will most certainly fix the water issue with the leaf gutter ,thats where the water seemed to be dripping from.

Thanks Again
Loretta

 

You're welcome.
You should pick up a tube of Dielectric grease from a parts store, then remove the PCM again and dry it once more and apply a small dab of the dielectric grease on each of the plug holes that a prong goes to. This will help insure a good electrical connection for some time to come. Good luck with it.

Also;
If you have to replace the PCM let me know as I have a couple of spares. I don't think you will have any further problems though.