If your 4WD switch looks like this 2WD, 4Auto, 4LO then...

[IAmTodd]

The other one has been around for a while, and they got 2WD!! Why can't us early Control Tracs get 4HI? Theres got to be a way!

 

[Yomie]

Hahahaha

Maybe if you can somehow take the wire that sends the pulsed signal when in auto4 and somehow get it to feed a continual signal to the t-case, you could have constant 4hi!

sounds like it would work, now, who's gonna test it

thats basically the opposite of what we are doing, we are taking the pulsed signal away to get 2wd, if you make the pulsed signal constant maybe it will be always engaged

 

[IAmTodd]

I understand that it runs off of a pulsed signal and all of that. In thinking that, wouldn't you think that sending a constant 12v power supply to the "brown" wire would force the clutch to engage the front full time?

What about switching computers from a '97+? and then doing the brown wire mod? If someone would like to take a look at wire colors and connectors to compare to mine. Or if they know already.

I love 4Auto. But I miss 4HI

 

[Yomie]

OK, i think i have to work at the shop tomorrow, if i do, i will take a reading(in voltage) off my brown wire in 4hi and let you know what it is, from there you can see if you can apply this same voltage to the t-case side of your brown wire and maybe it will work...

 

[IAmTodd]

I think I've found it!! I did a little work on it tonite and heres what I've found

2WD- 0 Volts
4Auto- .4 Volts
4LO- 11.8 Volts- Wasn't running so it reads a little low I'm assuming.

So my theory works I think. Applying a constant 12 Volt supply would engage the clutch fully and therefore make 4HI. Or atleast as much 4HI as 12 Volts can hold or something of that nature

So If someone could verify this I'd appreciate it. I mean take a reading of theres in 4HI. Thanks guys. I thiunk I might have solved it

 

[Yomie]

ok, i lost the leads to my multi meter, i'm looking for them, i'll try to find some

 

[IAmTodd]

I tried to do it on our '02. But the wire must be located somewhere else, or is a different color, or I jsut missed it. The one I tested on it had a constant 12 Volt no matter what setting it was in.

 

[dogfriend]

We actually did discuss this in the other thread in quite a bit of detail.

The problem with supplying a voltage to the clutch coil is that it wasn't designed to have a constant voltage applied to it. Ford controls the clutch by controlling the amount of current supplied to the clutch coil. The current isn't on all of the time, but instead is controlled by sending a PWM (pulse width modulated) signal where the current is varied by varying the length of time that the current is on compared to the amount of time that the current is off. The BW patent says that the frequency of the PWM signal is 33Hz (the on-off signal repeats 33 times every second).

I would speculate that you run the risk of burning out the clutch coil if you supply a constant current to it, because it may heat up more than it is designed for.

I could be completely wrong, but if you do burn out the clutch coil you will lose 4wd completely and will have to take the case apart to replace the coil to get it working again

 

[dogfriend]

Originally posted by IAmTodd
I

What about switching computers from a '97+? and then doing the brown wire mod? If someone would like to take a look at wire colors and connectors to compare to mine. Or if they know already.

I love 4Auto. But I miss 4HI

The problem with using the 97 + GEM is that the 97+ doesn't have the vacuum disconnect at the front axle - so the GEM won't engage / disengage the vacuum disconnect.

I really don't mean to be such a pain in the ass, but I'm an engineer - I can't help it

 

[IAmTodd]

So a multimeter wouldn't pick up the frequency of the pulse. It would just display peak or watever?

 

[dogfriend]

Originally posted by IAmTodd
So a multimeter wouldn't pick up the frequency of the pulse. It would just display peak or watever?

Yeah, a multimeter will probably give you the average voltage peak of the waveform. If you want to actually see the pulse, you would need to use an oscilloscope to see the waveform. Then you could find the actual frequency and see the amount of time that the current is on or off. The BW patent indicates that the time on varies between 4% and 86% in auto mode depending on the amount of slip detected by the speed sensors. The actual values may be slightly different because Ford doesn't appear to use exactly the same programming described in the patent, but they do use a PWM signal to control the clutch, according to the Ford Service Manual.

 

[Yomie]

Dear Dogfriend,

I think you lost me on PWM...

Sincerly,
Yomie




Hahahaha

 

[dogfriend]

Originally posted by Yomie


Dear Dogfriend,

I think you lost me on PWM...

Sincerly,
Yomie




Hahahaha

Introduction to Pulse Width Modulation

If you don't want to read it, scroll down to the picture - that will explain about 90% of it (i.e. a picture is worth a thousand words)