4wd died on the beach today...

[oldpaddy]

Had the wife and 2yr old. Plus no cell phone signal. Got stuck once and had a devil of a time getting up the steap dunes to exit. Scary.
So I get out there and I see the 4wd light isn't on, but a4wd was lit up even though I was in 4h. Then the a4wd kicked off and I was screwed.
I've been off the beach a couple of hours, and now the a4wd light is on and working (can feel it working). 4h and 4l isn't lighting up or working. Any ideas?
Thanks

 

[IL67BP]

Sorry I have nothing helpful to say but what year is your expy? And where is the a4wd light? Mine says 4wd when auto kicks on and when 4hi is on (shows same thing)... Then 4lo is something diff

 

[JUST4FUN]

bad shift motor on the transfer case

 

[oldpaddy]

Sorry I have nothing helpful to say but what year is your expy? And where is the a4wd light? Mine says 4wd when auto kicks on and when 4hi is on (shows same thing)... Then 4lo is something diff

Sorry, I thought my user info on the left displayed my expy. It's a '97 5.4l
The lights are on my dash, selector near the radio.

 

[oldpaddy]

bad shift motor on the transfer case

Thank you!

 

[panda24619]

that could be it. make sure your switch is plugged in fully. thats the easiest thing to check. pull the cover off thats around the radio where the switch is. and check the plug. unplug it, look for any corrosion, most likely none, then plug back in. then i would check the shift motor.

 

[oldpaddy]

that could be it. make sure your switch is plugged in fully. thats the easiest thing to check. pull the cover off thats around the radio where the switch is. and check the plug. unplug it, look for any corrosion, most likely none, then plug back in. then i would check the shift motor.

Ha! That's the first thing I did when I was on the beach. Then I checked the fuse.
I don't know how I got up and over those dunes!

 

[panda24619]

i do all the time in 2wd. just have to stay on the skinny pedal and slide everywhere. also 15psi helps.

 

[oldpaddy]

i do all the time in 2wd. just have to stay on the skinny pedal and slide everywhere. also 15psi helps.

I was at 12psi until I got stuck. I dropped it down to 10psi and that helped. I don't know what beach you're driving on, but I wouldn't reccomend lower cape cod beaches and dunes without 4wd. Haha I feel like a hero for getting my family off the beach!

 

[toms89]

I have my doubts about the shift motor being the issue. It shifts the transfer case between hi and low range. If it fails I would assume you would just be stuck in whatever range it happens to be in. You would have one or the other. I was thinking along the lines of the center axle disconnect but if it failed you should have no 4wd period.

 

[oldpaddy]

I have my doubts about the shift motor being the issue. It shifts the transfer case between hi and low range. If it fails I would assume you would just be stuck in whatever range it happens to be in. You would have one or the other. I was thinking along the lines of the center axle disconnect but if it failed you should have no 4wd period.

You would have a better idea than I. I looked at the shift motor and it is rusted pretty bad. A4wd is working, the light goes on and I can feel it when I'm backing into my driveway. I live on a dirt road and the front tires rip up my driveway a little when I back in.

 

[JUST4FUN]

its a 97 so it sounds like the motor never shifed the trasfercase, if it did the light would of lit on the dash so it sounds like the allwheel drive was trying to work, but the center axle disconnect might have a problem too , remember the shift motor does nothing going bettwen 2hi and A4WD it all electronic kinda like the brown wire mod.
97 had switch reading 2HI, A4WD,4HI,4LO

 

[JUST4FUN]

You would have a better idea than I. I looked at the shift motor and it is rusted pretty bad. A4wd is working, the light goes on and I can feel it when I'm backing into my driveway. I live on a dirt road and the front tires rip up my driveway a little when I back in.

It sounds like the A4WD is working ok im still thinking its the motor on the Tcase

 

[oldpaddy]

It sounds like the A4WD is working ok im still thinking its the motor on the Tcase

I'm going to replace the shift motor by Friday, so we'll find out shortly.

Just wondering, why did I lose a4wd while on the beach, but regained it a few hours later?

Thanks guys for all the help! You guys are the best!
Hope everyone is having a great memorial weekend!

 

[toms89]

http://www.youtube.com/watch?v=Al6sO_2A90w

 

[JUST4FUN]

I'm going to replace the shift motor by Friday, so we'll find out shortly.

Just wondering, why did I lose a4wd while on the beach, but regained it a few hours later?

Thanks guys for all the help! You guys are the best!
Hope everyone is having a great memorial weekend!

as Tom said this might be a vaccum problem . look at the front diff there is a actuator
that is vaccum controled follow the hose till you find the leak

 

[oldpaddy]

http://www.youtube.com/watch?v=Al6sO_2A90w

Thats a great vid! I saw that last night. My shift motor looks as rusted as that one. The part is pretty cheap, so I figure I can't lose by changing it. Even if it's not the problem.

 

[toms89]

as Tom said this might be a vaccum problem . look at the front diff there is a actuator
that is vaccum controled follow the hose till you find the leak

I took this from my 2000 expy service manual :
Please note that the 2000 expy does not have center axle disconnect but the 1997 does..

Principles of Operation

The automatic 4-wheel drive A4WD system is a full time 4-wheel drive system with an electronic shift 4x4 system that allows the operator to choose between three different 4x4 modes. The operator can switch between A4WD, and 4WD high mode at any speed, and 4WD low mode. To engage or disengage low range, the vehicle speed must be less than 5 kph (3 mph) , the brake depressed, and the transmission must be in NEUTRAL.
In A4WD, the generic electronic module (GEM) varies the torque split between front and rear drivelines by controlling the transfer case clutch. The transfer case clutch allows for slight speed differences between the front and rear driveshafts which normally occurs when negotiating a corner on dry pavement. When the rear wheels are overpowered, the GEM detects this slip condition, and the duty cycle to the transfer case clutch is increased until the speed difference between driveshafts is reduced.
The 4WD mode switch is a rotary switch which allows the vehicle operator to choose between A4WD, 4WD high, and low range positions. There is no A4WD lamp, and the 4x4 lamp is controlled by the GEM and tells the owner that the vehicle is in 4x4 high mode. The LOW RANGE lamp is controlled by the PCM.
The vehicle speed signal is hardwired between the powertrain control module (PCM) and the GEM, speed control, overhead message center, air suspension, and EVO steering. The instrument cluster also receives the speed signal, but receives it over the standard corporate protocol (SCP) communication network. The PCM determines vehicle speed from the output shaft speed (OSS) sensor which is hardwired directly to the PCM.
The Hall effect sensors are mounted to the transfer case and are used to determine the speed of the front and rear driveshafts.
The shift motor sense plate, an integral part of the electric shift motor, is used to inform the GEM what mode the transfer case is actually in.
The digital transmission range (DTR) sensor, located on the left side of the transmission, informs the GEM of the transmission gear position.
The 4x4 shift motor relay is a module containing two relays which, under the control of the GEM, shift the transfer case shift motor between the three 4WD modes.
The torque on demand (TOD) relay is used to activate the A4WD clutch within the transfer case by the GEM. This relay controls the torque split between the front and rear axles.
The throttle position signal is hardwired from the PCM to the GEM. The GEM uses the throttle position to anticipate a rear wheel slip condition when the vehicle is in A4WD.

After reading this and looking at diagrams I believe you could be on the right track. I originally believed the clutches in the transfer case engaged/disengaged the 4wd and the shift motor was purely for engaging/disengaging the 4low planetary. Looks like the shift motor may have more than one function after reviewing this.

 

[toms89]

 

[oldpaddy]

Interesting...
Battery died, jumped it and now 4wd appears to work. I switched to 4h and 4l and I heard the clicking and the "4x4" light came on. I'll see if it's working later. I can't remember, is the "4x4" light come on for both 4h and 4l, or does each gear have it's own light?