New to the forum and i'm having a problem trouble shooting the electrical on this truck. On start the 4wd indicaters illuminate on instrument cluster then go out,dash slector has 12 volts to the bulb that is burnt out ohms on the different selections on the 4wd location seem to be correct. According to my owners guide only fuses are 17 under hood transfer case motor, fuse 23 under the dash 4wd solenoids book has no relays? No voltage to transfer case switch motor, 12 volts to solenoids but no clicking. Haynes manual has just about as much information as the owners guide. Can't check accuator till i get power. My question is there a way to check the generic electric module while it is still connected to the fuse box and is there some relays i'm missing or the location of them? I understand that then switch on the dash sends low signal to the gem then the gem sends a signal to the shift selector the returns to gem then back to the shift selector if it reconizes the shift selection and the speed. All help with my situation would be appreicated thanks stumped. PS NO ELECTRICAL PROBLEMS OTHER THEN 4WD. My problem is the 4wd doesn't work.

 

What exactly is your problem?

 

4x4 won't engage no power to shift motor? Are the relays for the different sequences the gem does in the gem itself or can you tell me there location? Owners guide shows no relays, Haynes manual doesn't refer to there location.

 

4x4 won't engage no power to shift motor? Are the relays for the different sequences the gem does in the gem itself or can you tell me there location? Owners guide shows no relays, Haynes manual doesn't refer to there location.

 

The relays are activated by the GEM. Fuse 17 (underhood fuse box) powers the transfer case shift relays and the GEM grounds the relalys. Fuse 12 (interior fuse box) powers the front axle disconnect/connect relays. Hope this helps.

 

Don't have my 97 EVTM handy, so the info I have is for the F-150 ( cannot confirm if they are exactly the same, so it is really a SWAG ).

You have power from CJB ( aka Central Junction Box, cab fuse panel ) fuse #23 to the top of the vacuum solenoids ( the White w/ Light Blue stripe wire on both ).
If you do not have power to the transfer case, the GEM won't bother with trying to activate the front axle.

Appears that you have gone another route to get here, but just to be sure

Lift and support the front of the truck so the front wheels are off the ground ( take safety precautions, chock wheels, jack stands, etc )
Key on, engage 4x4 and try to turn the front drive shaft.
If it turns it is a problem with the transfer case ( and checking the vacuum solenoids is a waste of time right now ).
If it doesn't it is a front axle engagement problem.
Not sure what you were checking for power on the transfer case, could be the transfer case is seized up. Could try having someone switch from 2WD to 4H while hitting the transfer case with a dead blow hammer ( not a metal hammer, it can damage the transfer case ).

Did you remove the connectors to the transfer case, and see if the pins in the connector are clean ?

The F-150 has a transfer case electric clutch relay in the RPO relay block.
Not 100% sure if this is the additional one under the hood, this is a 1/2 size ISO relay ( marked unknown in this picture ) :


This is what power the magnetic clutch coil in the transfer case, once the GEM grounds the coil on this relay.



You can check if the coil is getting ground from the GEM by checking for continuity to ground from the terminal to the GEM in the socket, or you can just check for VDC with a meter to the terminals #1 & #2, when someone switches the mode switch to 4W or 4L.



Just a few thoughts on the topic, again this is for a '97 F-150, so it very well could be different on your 97 EXPY.

 

Thanks SScully and Merry Xmas I'll start checking things right away.

 

So what were the results?

 

I also have a 97 expedition, XLT 5.4L 4x4.

On mine, I have been having the flashing A4WD light intermitently for better than a year now. Lately, it has stopped shifting into 4x4h/l. In A4WD it will usually shift into 4x4 after having just starting the vehicle. while driving,it is more often than not getting an error that disengages the 4x4 and causes the light to start flashing, it will not go back into A4WD until I shut off the engine and restart it. When shifting into 4x4h/l, I am no longer hearing the second relay click in. I used to hear click click click, when shifting from 2WD to 4WDH. I have not yet crawled under the truck to check for power at the electronic shift motor, but I am wondering if it would be getting power in 4WD since I am not hearing the relay. Also I looked in the dash for these two relays, and cannot find them. I removed all the bezels on the dash, and the oval shaped insert on the top passenger side of the dash, and cannot locate them. It sounds like they might be coming from the far right side of the dash based on the one click I still hear when shifting into A4WD.

I do not doubt that I may have more than one problem to solve at this point, but any help would be appreciated.

sscully, thank you for the picture of the relays under the hood. I have been looking for that info for 3 years.

 

Hey guys, new to the group and I realize this post is old but I am hoping you can help me. I have a 1997 expedition, it will only go into awd mode, not 4 high or 4 low, when you turn the switch to 4high or low, it just stays in awd mode. I replaced the shift motor, still the same problem, and now, when i have it in awd mode, the front tires won't turn, unless the vehicle is in the air with no restriction on the front tires, so I am assuming the clutch system is slipping, so my question is any idea why it is not going into 4high and low, and where is the clutch system located for these vehicles, in the transfer case or in the front differential? any info will be greatly appreciated!!

 

any updates to this?