Hey guys! I asked a question about this problem in the Expedition forum months ago and never got a response, so I am hoping someone here can help me out, since our trucks are pretty similar. When I start my 97 Expedition the qauges read perfect but after a few minutes the oil pressure gauge will usually creep up to the high point and the voltage gauge will usually do the same or drop to the low point. That is driving with the headlights off, now when I turn my headlights on the gauges will either peg out on high or drop to low. The fuel gauge will occasionally drop to empty but only about half of the time. I am dumbfounded and have no idea what the problem is, the truck always runs great, just has the gauges acting funny. It sounds like a short somewhere but hitting bumps going down the road has no effect or me wriggling the wires with the dash apart. I appreciate any suggestions that come my way and hopefully explained this clear enough. Thanks!

 

That's a strange one. Haven't seen that , but if I had to guess I'd say it had something to do with the GEM. Possibly water intrusion/corrosion at the GEM connector, behind the fuse block and under the dash.

So it's just those 4 gauges then?

 

Yes sir, just those four. I have read about the water intrusion problem these trucks had but the Gem module doesn't look to have ever seen water but looks can be deceiving. I also kind of ruled it out cause the problems I read about coming from a bad Gem had nothing in common with mine but that also doesn't necessarily mean anything. I will check it out again and look into replacing it cause at this point I don't have a clue where to begin on fixing this. The truck has had the engine replaced with a P.I head engine so I have wondered if something from that may be the culprit. I bought this truck last year with the intention of just keeping it a year to get through some financial hurdles but it has earned a spot beside my other vehicles and I would like to fix this one problem to make it almost perfect. Thanks Jbrew!

 

I was thinking about the cluster PCB, - the circuit board, but I don't know..- Doesn't sound like a cracked solder joint or board IMO. It's possible tho, - look at those solder joints magnified, - when looking for cracked joints. That's happened in the past, - it just didn't present this sort of problem.

Do you have a circuit/wiring diag ? Perhaps they tie into a relay that's malfunctioning. A bad relay needs a little time to heat up before it starts malfunctioning. I think you mentioned a delay, or problems occurring a short time after start.

 

I never did give a relay any thought. That does make since and I will look for a wiring diagram to see which one controls them and see if they are both on the same one.Thanks!

 

Turn the key to run , or just start the truck. A bad relay is usually real warm/hot when touched. Doesn't have to be, - most of the time.....

 

check solder joints as mentioned, but I really suspect a ground issue as you can change operation by activating other circuits. Check your service manual for ground location and do a volt drop test on the ground wire. No volts should be observed.

 

Good Idea! - The grounds are behind the kick panels. Both sides of the cab. Green 10mm heads.

Ford F150

There's one cab strap that corrodes on the passenger side under the cab. The cab to frame ground.

Passenger side in the engine compartment on the firewall there's 3 grounds, - easy to find. Furthest over is the PCM ground, battery misc, -then cab engine ground.

The grounds you want are behind the d-side kick panel. Well, there's one in plain site and another, just a little further forward and up a little higher from that one. Approx 8" in both directions.

Not sure how I remembered all that; best thing to do is go off a diagram for yours in particular. The ground pertaining to the fault area of course.

Keep in mind, you can't just see a bad ground, you need to test it. I clean them regardless, - pull the bolt then wire wheel it. Clean the connectors and take a little paint off the cab where they tie down.

You have a good diagram don't yuh ?

 

Have you had the battery and alternator tested yet?

 

That type of behavior is quite often a weak battery.

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Thanks for the tip. I will give them a check today.

I don't currently have a service manual but will try to find one. Thanks for all the helpful info, jbrew.

The battery is brand new and I have never suspected an issue with the alternator cause the truck has never failed to start or shown symptoms of it being bad.

I know exactly the symptoms you are talking about cause my F150 done something similar when it's battery went bad. It's two totally different symptoms though, the F150's gauges would flutter at startup, this problem only occurs after the truck has been running a while.

 

On further review, I see what yoiu are saying about the symtoms being different.

 

So, I went outside to try and get a video for you guys to see. So far the problem isn't really showing it's face yet, so it sounds like something has to get warm for the problem to really begin. In this video just skip ahead a minute or so at a time and you will see the oil pressure gauge slowly but surely moves to the high point. The clicking noise you will hear is me cycling my headlights on and off trying to get the gauges to move. The truck had only been running about five minutes when this video was taken and it's usually running for a little bit longer when I have the main problem. The oil pressure gauge is predictable and does this every time right after startup.

 

Man that truck is quiet. You have a vacuum leak btw.

 

LOL It's the hot air intake the previous owner installed. The thing whistles like crazy for some odd reason.