Is my 4WD working???

[dogfriend]

If you look for the fuse that supplies the Torque on Demand relay via the Accessory Delay relay, that should cut power to the transfer case clutch.

 

[topo4u2]

Yes, I will look into that fuse and let you know what happens. If it stops that front shaft from turning in 2wd than on goes a quick disconnect to the brown wire. Cheap fix for sure. Man Im sure not impressed with the BW 4405!
I really miss my New Process 208!!!!

 

[topo4u2]

Hey, does anyone know where the torque on demand relay is on a 95??? I may just unplug it.

 

[mikefox]

hope some of this might help...

The torque on demand relay is located behind the radio to the right of the center air duct. The GEM is to the left of this air duct. With the center bezel and radio out of the way you will see what I mean. I am going to attach some pics from the Ford manual to show the wiring connectors for these pieces. I am also going to include some other pics for the Dana35 and the T/C itself. Here goes:

Dana35_1
Dana35_2
T/C
Electric Shift Control 1
Electric Shift Control 2
Electric Shift Control 3
Electric Shift Control 4
GEM Electric Shift Control 1
GEM Electric Shift Control 2
GEM Electric Shift Control Pinout
My 4hi Idea Decided it wasn't a good idea to apply 12v to T/C clutch.
T/C Motor/Shift Relay Connectors
T/C Connector
T/C Relay

 

[dogfriend]

Re: hope some of this might help...

Originally posted by mikefox


Thanks for posting this. Now I understand the differences between the 95-96 system and the one in my 97.

I think it might be possible to use your idea for getting 4wd High, but you need to figure out how to limit the amount of current supplied to the transfer case coil. The safest way to accomplish this would be to come up with a scheme to supply a PWM signal like the GEM does. Another way might be to use a resistor in the circuit so that that your current is equivalent to the average current sent by the Torque on Demand relay when the system is in 4wd Low. I don't know if constant 12v will burn out the coil immediately, but I suspect that it would over a long period of time or if used continuously a few times.

 

[dogfriend]

Topo4u2:

I have a new theory for what your problem is:

The solenoid which disengages your vacuum disconnect is either sticking or has an intermittent connection.

This explains why your vacuum disconnect was working (sometimes?) when your 4wd Switch was hosed.

It also explains why sometimes your driveshaft is rotating and sometimes not.

What do you think?

 

[topo4u2]

Thanks mike for the post again...a lot of excellent electrical pics!!
I may just yank a fuse and see what happens before I dig for the relay..I will likely know quickly if power is keeping my clutch activated in 2wd.
My truck is headed back in the shop where the oringinal saftey was done(not Ford) they have to install new rear emergency brakes as they never checked them and they have been metal to metal for god knows how long. They are also checking a few other things. This will all be the deciding factor as to whether we keep her or not.

 

[topo4u2]

Hi all, well here we go again, more questions.
Well for sure I do not have four wheel drive, its snowing out and I took my X for drive. No chance of those front wheels spinning in either 4Auto or 4 low. Besides having a completely screwed up transfer case which I believe to be the case, I'm also thinking that power is not going down that brown wire from the GEM or relay...have to check the wiring diagram for sure. Maybe that brown wire is cut or a bad connection at a plug? My big question is,...is there any way to check for a voltage reading on that brown wire? Does it get 12 volts in 4 low?
I would love to get this 4 wheel working. If I can positively determine that the clutch in the case is shot..its going straight back to Ford Ugg!!
please help!!

 

[dogfriend]

Originally posted by topo4u2
Besides having a completely screwed up transfer case which I believe to be the case, I'm also thinking that power is not going down that brown wire from the GEM or relay...have to check the wiring diagram for sure. Maybe that brown wire is cut or a bad connection at a plug? My big question is,...is there any way to check for a voltage reading on that brown wire? Does it get 12 volts in 4 low?
I would love to get this 4 wheel working. If I can positively determine that the clutch in the case is shot..its going straight back to Ford Ugg!!
please help!!

Are you sure that the vacuum disconnect is working? Earlier, it sounded like it might have an intermittent problem.

You should be able to test for voltage either at the Torque on Demand relay or at the connector next to the shift motor. I don't think that you will get exactly 12V, but you should get some reading between the brown wire and ground. Someone in the other thread measured the current in 4wd Low and got .6 amps.

Its a PWM signal which means sometimes its 12V and other times its 0V. The signal looks like a square wave with a frequency of 33 Hz if that makes any sense. Your reading will be the average of the voltage.

 

[topo4u2]

Hey DF, how are you? Iam a pain for sure. Yes, the front vacuum disconnect is working. I checked it several times. It sounds like that brown wire might have 12 volts in 4 low? but different voltages during 4 auto operation?
It just snowed here tonght...what a piss off! Well, the wife and I decided that we have no damm choice but to head back to that Ford dealer on Monday and see what comes of it. I will be very surprised if they dont tell me that I need a GEM or relay or anything but that piece of crap transfer case they installed.
If it clears up tomorrow I will crawl under with my multimeter and check for voltages. That should cancel out anything electrical

 

[dogfriend]

I was hoping that you would find that one of the vac disconnect solenoids wasn't working right, because that would be easy to fix.

Even in 4wd Low, I don't think it will read 12V, but you should get some voltage reading which will be the average voltage of the PWM signal.

The difference between the voltage in 4wd Auto and 4wd Low should be different though.

In 4wd Auto, the clutch is only getting about 4% of the current possible. If the rear wheels start slipping, then the GEM increases the current in steps of 4% (or is it 8%?) until the front and rear are turning the same speed.

In 4wd Low, the GEM ramps the current up so that the front and rear axles are both getting about 50% of the torque. According to the BW patent Dead Link Removed ,the current for 4wd is about 86% of the current possible.

I wouldn't be surprised if the dealer tries to replace your GEM next. They should test everything else first to rule it out, but those guys will probably just go for the GEM next because its easier.

Are there any other dealers you can take it to?

 

[topo4u2]

Yes, we have another Ford dealer here. Im not sure if I should go that way because if it turns out to be the transfer case then the original dealer is liable to fix it(wouldn't you think)? Besides they have a loan a car. Although that is not much consolation after all this.
I will try and get under her tomorrow and test that brown wire.....who knows maybe a fuse?

 

[dogfriend]

I'm thinking that a different dealer might be able to verify that the transfer case is the problem (or not). I wouldn't have a lot of confidence that the guys who installed the used transfer case will be able to figure out the problem. If the second dealer says the transfer case is messed up, then I would go back to the first dealer so they could make it right.

I keep thinking back to the post you made earlier where you said that the fluid was dark in the used transfer case. It shouldn't have been. Either someone put in regular gear oil because they didn't know any better, or the ATF was really contaminated badly. That could mean that the clutch is messed up in the used transfer case.

I think its also possible that the GEM is messed up, and causing the vacuum disconnect problem and the 4wd problem. I think that the best way to verify that the GEM is bad would be for someone to hook up a scan tool to see if it is working the way it is supposed to. They should be able to scan for PID's (parameter ID's) that will tell them if the GEM is trying to engage the clutch and the vacuum disconnect. They may also be able to "flash" the GEM to update its program if it isn't working right.

Before replacing the GEM, they should verify that the Torque on Demand relay is ok, because that could cause the 4wd problem also.

 

[topo4u2]

Ok, here is the deal. Just got inside from a snowy ground...hands are frozen!
I jacked her up on all 4's. Put it in 4wd auto....6volts to brown wire....front axle engaged via vacuum solenoid...put her in 4low...12 volts to brown wire...front axle still engaged via vacuum solenoid...put her in drive and NO front wheel action. The shaft between the case and front diff has a fair amount of friction but no torque to front whatsoever!! Ok now Im pissed...its for sure a chunk transfer case....calling dealer in am for an appointment!!!
wish me luck.

 

[topo4u2]

Continuing on with this scenario....does anyone know if it is possible for one of the speed sensors on the case to not allow that front driveshaft to turn??? I would think that the speed sensors would send a signal to the gem to ease up on voltage to the clutch? I'm really digging for answers on this one!! If I knew a speed sensor could cause that front shaft to stop spinning I would change them no problem....but I really do feel that I have a burned out (slipping) case clutch.

 

[dogfriend]

Good luck.

Hopefully they will do the right thing and replace it without too much hassle.

 

[dogfriend]

Originally posted by topo4u2
Continuing on with this scenario....does anyone know if it is possible for one of the speed sensors on the case to not allow that front driveshaft to turn??? I would think that the speed sensors would send a signal to the gem to ease up on voltage to the clutch? I'm really digging for answers on this one!! If I knew a speed sensor could cause that front shaft to stop spinning I would change them no problem....but I really do feel that I have a burned out (slipping) case clutch.

If you are getting voltage on the brown wire but no torque at front wheels, it must be the clutch.

If it were the speed sensor, you should get a flashing 4wd light. Also, in 4wd Low, the sensors are taken out of the loop; the transfer case clutch should be locked no matter what.

 

[topo4u2]

Thanks DF, that is good info, I did not know that the sensors were taken out of the loop in 4low. Well, just got finished dropping her off at the Ford dealer..yes the same one! Got there 2002 Focus loaner. Told them the situation.....now lets wait and see what happens. This could get interesting....I wonder if they will agree that the used case is crap? Not much left that it can be.

 

[Stumpgrinder]

Hello Everyone and Happy Thanksgiving to those in the USA!

This thread has been dormant for 2 years but I didnt want to start another because my explorer's symptoms are exactly like what CJeff describes in the first post. Hopefully this reply will be noticed.

I have a late-year '96 XLT with control trac and the 4.0 V6, it has about 150K miles on it. When I select 4W Auto (high) on the dash switch the dash light comes on and the system appears to be working but after a minute or so the "4W Auto" and "4W Low" dash lights blink on and off several times then go off. At this point the vehicle feels like it is locked in 4W Low, if I make turns on dry pavement the front tires scrub and the drivetrain groans. If I put it park and select 2WD everything goes back to normal.

I took it to AutoZone and the diagnostic hookup found no error codes, not sure if the guy knew what he doing.

So I'm thinking that I should remove and clean the front and rear speed sensors. To make sure I am after the right thing, is this the rear sensor: Rear Sensor. And is this the shift motor that must be removed in order to access the front sensor (pointers to mounting bolts): Shift Motor

Do I have to worry about any fluid draining out when I pull these items? Will I need to replace any seals? How exactly should I clean the sensors?

A couple other things: I recently replaced the fluid in the transfer case, at this mileage I realize it was way overdue but the fluid was still pretty clean looking. Much cleaner than me after I got Dextron all over my shirt trying to refill the case anyway I have been guilty of NOT putting the vehicle in 4WD every month or so, could something be "stuck" somewhere? Also, I recently traced a problem with the defrost control to a broken vacuum line, are there any vacuum lines that (if they were leaking) could cause these 4WD symptoms?

Thanks very much,

russ

 

[TPLYNCH]

The flashing lights would be an indication of the speed sensors being bad, or the GEM misinterpreting the signals, and based on your description of the problem, engaging the clutch in auto. The motor is only used to get into 4low. If you engage 4low, does it work? Removing the shift motor will not include any fluid issues. The sensors are just magnets, so cleaning shouldn't be difficult.