4X4 High/Low flash of death

[jkstang78]

Ok I have done some of the Searching around on this topic. I read a lot of what came up with still no answeres. I understand the speed sensor can be bad. I also see that people have unpluges the battery also.

But My ? is I want to change out the speed sensor. The Battery trick didn't work for me. I just went to the auto parts store and I got this sensor. Pic below

Now this is the sensor I was just given. Which is not the right sensor.

I thought the sensor above was this. But I noticed that that wire goes to the motor.

Now is this the Sensor that needs to be changed.

 

[drdoom]

The bottom photo is the VSS (Vehicle Speed Sensor)...for the speedometer.

 

[imp]

What year is vehicle? Mine does not have the 2-wire dingy coming out of the case, just the clutch wire. imp

 

[drdoom]

Control Trac...

What year is vehicle? Mine does not have the 2-wire dingy coming out of the case, just the clutch wire. imp

Maybe the 2 wire sensor (Hall Effect) is for a Control Trac variant. Mine has those (front & rear shaft), and it is a Control Trac.

 

[jkstang78]

It's a 1996 and that (Hall Effect) sensor is a 3 wire sensor. I didn't know what the name of the sensor was until yesterday. When I saw a thread on here on how to rebuild a transfercase.

This thread.
http://www.explorerforum.com/forums/showthread.php?t=182071

My lights flashes 6 times every 2 minutes. I have read that it could be a speed sensor. So what I'm trying to figure now is which sensor is it. Is it the vehicle speed sensor or that Hall effect sensor that need to be changed

Does anyone know what the Hall effect sensor does?

 

[drdoom]

Hall Effect Sensors

There are two Hall Effect Sensors in that case, one for the front drive shaft, one for the rear. They sense any disparity between rear wheel speed and front wheel speed, i.e the rear wheels are spinning so we let the GEM know that and the GEM powers up the clutch pack via electromagnet, sending power to the front wheels (4WD).

 

[imp]

There are two Hall Effect Sensors in that case, one for the front drive shaft, one for the rear. They sense any disparity between rear wheel speed and front wheel speed, i.e the rear wheels are spinning so we let the GEM know that and the GEM powers up the clutch pack via electromagnet, sending power to the front wheels (4WD).

Any idea why they would have done this when they already had speed data coming from the front and rear ABS sensors? imp

 

[drdoom]

Any idea why they would have done this when they already had speed data coming from the front and rear ABS sensors? imp

That is a good question, imp, wish I had a good answer...Only thing I can think of is that perhaps the data coming from the case is somehow more pertinent, given that it is read off of the 2 drive shaft tone rings, or maybe it just simplifies the wiring harness layout.

 

[jkstang78]

There are two Hall Effect Sensors in that case, one for the front drive shaft, one for the rear. They sense any disparity between rear wheel speed and front wheel speed, i.e the rear wheels are spinning so we let the GEM know that and the GEM powers up the clutch pack via electromagnet, sending power to the front wheels (4WD).

Merry Chirstmas everyone Thanks for this info. Ok so what do I need to change to fix the problem I'm having. which is the high/low 4 wd lights flash 6 times every few minutes. Do I need to change out these 2 Hall Effect Sensors or do I need to change out the Vehicle Speed Sensor.

 

[gmanpaint]

Does the rig drive in all gears? How is the shift patterns going from 1st thru 4th? Smooth, harsh, same? Does reverse work? What drive is it in now, & will it shift into 4hi or 4low?

I have gone thru a few of these cases, and have never seen a hall sensor go bad. The VSS has gone bad for me. I have also had a couple other things go bad. This is what I know what to do to figure it out.

If the ABS light is on, it could be one of the 3 sensors gone bad, either mechanically, or electrical.

If the VSS is bad, you would have very erratic engine / trans behavior. The RPMs would jump up & down, the trans wouldn't know which gear to be in and jump thru them in a crazy manner, eventually the trans would kick itself into Neutral and you wouldn't be able to move at all. The speedo needle would jump up & down also.

The 4405 can have multitudes of problems. Drain the fluids and inspect for contamination. Look for white plastic=shift fork. Look for copper particles=clutch pack.

Remove the shift motor and do the following......

With a helper, hold the shift motor and look at the backside of it. Have the helper turn the 4x switch, and watch it. If it moves in sync with the switch its good, if not, its bad.

With the motor off, Trans in Neutral, try to turn the shift rail that sticks out of the case where the motor was. It does not turn a full 360*, so just go from H to L back and forth, and listen / feel for a "click". If it locks into both ranges, It should be good. If it gets harder as you move it, it could be a blown clutch pack, a jammed shift fork a broken helical coil, or a few other things.


Good luck!

 

[drdoom]

Test them

I would test the sensors before I replaced anything. YMMV

 

[muhl5443]

the first sensor that you posted is the wheel speed sensor for the rear differential.

 

[gmanpaint]

the first sensor that you posted is the wheel speed sensor for the rear differential.

96 has the VSS in the t-case. The rear sensor is just the ABS sensor.

 

[drdoom]

ABS Sensor

96 has the VSS in the t-case. The rear sensor is just the ABS sensor.

ABS Sensor is in the differential, I think.

 

[gmanpaint]

ABS Sensor is in the differential, I think.

Correct, and the 1st pic is it.

 

[jkstang78]

Does the rig drive in all gears? How is the shift patterns going from 1st thru 4th? Smooth, harsh, same? Does reverse work? What drive is it in now, & will it shift into 4hi or 4low?

I have gone thru a few of these cases, and have never seen a hall sensor go bad. The VSS has gone bad for me. I have also had a couple other things go bad. This is what I know what to do to figure it out.

If the ABS light is on, it could be one of the 3 sensors gone bad, either mechanically, or electrical.

If the VSS is bad, you would have very erratic engine / trans behavior. The RPMs would jump up & down, the trans wouldn't know which gear to be in and jump thru them in a crazy manner, eventually the trans would kick itself into Neutral and you wouldn't be able to move at all. The speedo needle would jump up & down also.

The 4405 can have multitudes of problems. Drain the fluids and inspect for contamination. Look for white plastic=shift fork. Look for copper particles=clutch pack.

Remove the shift motor and do the following......

With a helper, hold the shift motor and look at the backside of it. Have the helper turn the 4x switch, and watch it. If it moves in sync with the switch its good, if not, its bad.

With the motor off, Trans in Neutral, try to turn the shift rail that sticks out of the case where the motor was. It does not turn a full 360*, so just go from H to L back and forth, and listen / feel for a "click". If it locks into both ranges, It should be good. If it gets harder as you move it, it could be a blown clutch pack, a jammed shift fork a broken helical coil, or a few other things.


Good luck!

WOW thanks for all this info. The truck does drive in all 4 gears and reverse. It does shift smooth when driving. I have notice that when coming to a full stop that it acts a little weird. The truck wants to almost stall and the trans has a very slight kick down could be going into Neutral. Once I step on the gas everything starts to work fine again. There is no ABS light on. I Don't think the speedo cable is jumping since haven't noticed. But that just be something I didn't notice. I'll check it when I dirve it later.

Now as far as driving and being able to shift on the fly into 4wd drive High or Low I can't do that at all. The 4wd high light comes on and then after a few minutes it will give me the 6 blinks of 4H/L. Now If i come to a complete stop and throw the switch to 4H. I hear the motor click on. It will also go into 4WD. I haven't tried to drive with it like that and see if the lights will start blinking. I guess I will find out the next few days. Said there is going to be 6 to 12 inches of snow. So that will give me time to test that system for sure now.

I'm going to have to try the shift motor Thanks for the bit of info.

 

[gmanpaint]

There is no speedo cable in your rig. Its just sensor wires from the VSS.

The shift motor only works for low range. It can only be activated while stopped, in neutral, and the brake pedal depressed. Same for taking it out of low range.

4wd H can be activated on the fly as it does nothing for the shift motor. It only sends a signal to the clutch pack that is used for 4wh.

There is a chance of internal damage to the t-case if the lights are blinking.

No ABS light means you have a good circuit, so I would forget about that all together.

There are more things that can be wrong, such as the GEM, and 4x4 module. Just have to keep digging with it.

Have you checked the fluid level in the t-case yet? What color is it? Was it low? Do you see any signs of a leak? Check the obvious first.

 

[drdoom]

Correct, and the 1st pic is it.

OK, here is a photo that shows the transfer case sensors:

 

[gmanpaint]

Those are the hall sensors. Used for the GEM.

 

[drdoom]

Rear Output Seal

From your photo, it looks like it is leaking a bit.