Electrical / 4x4 Problem(s)...?

[Jcovill125]

Ok so here is my story..

I was driving around one day and I hear the audible ound of the 4x4 engaging ya know *tik-tik*. But I didn't turn the switch into 4HI.. So I switch into 4HI, wait a few seconds then switch back into 4AWD. Thinking nothing of it I go about my business until about 5 minutes later start to feel like the truck is bogged down a bit and I feel like I lost power, then I hear a loud THUD come from under the truck where the transer case should be.. Then gain power back and everything seems find and dandy.. A few days pass and I decide to switch into 4HI as soon as I do the truck really boggs down and I feel like I lost 80% of the power steering.. So I quickly switch back into 4AWD and shift into reverse to make double shure I'm no longer in 4x4... I then did a hard reset, the truck feels like its back to normal now, but I'm almost afraid to switch back into 4HI again...

Any sugestions?

Sorry for any mispelled words..

BTW, I have a 2002 XLT 5.4 w/ tow and off road package.

You guys are awesome, and I'm looking forward to your help! THANK YOU.

 

[mindgame]

Sound like you may have bad speed sensor and it is not throwing a ABS light...

It kinda sound like the traction controls are applying abs to balance out your tire spin as well as retarding the engine..

 

[Jcovill125]

Sounds like an easy enough fix. I'll get on that and see if my bugs go away. Thanks for the help!

 

[toms89]

Sound like you may have bad speed sensor and it is not throwing a ABS light...

It kinda sound like the traction controls are applying abs to balance out your tire spin as well as retarding the engine..

The 1st gen expys are not that sophisticated. They do not use anti lock brakes for a form of traction control. They started that on the later gen expys possibly along with torque reduction. This also required open differential in order to operate correctly.


To the op... are you using 4wd on pavement?? If so any slight turn and it will begin to bind up. Going dead straight it should not notice unless your front and rear tires are different sizes.

It does monitor front and rear speed sensors and if they do not agree within a certain percentage it will engage 4wd. Basically if it senses higher wheel speed in the rear it will engage 4wd. But its designed to allow for a percentage of normal tire wear and differential between the front and rear due to turning.

 

[mindgame]

The 1st gen expys are not that sophisticated. They do not use anti lock brakes for a form of traction control.

Dangs!!! I keep forgetting about 1st gens!!! Thanks for the reminder!

 

[toms89]

Dangs!!! I keep forgetting about 1st gens!!! Thanks for the reminder!

You and your advanced technologically sophisticated expy... LOL.

 

[Jcovill125]

Actually yes, the second time I switched into 4wd I was on dry pavement... So you're exactly right in how it should have acted. and I now feel dumb lol.. All tires are the same size too. So I guess the expy did its job.

But what I'm still confused with is why would It switch into 4hi by itself? Bad relay maybe? I have been driving since and everything feels normal. Just that one thing really freaked me out. Better to ask than to find out the hard way. BTW and I'm sure this is redundant to you guys.. but, I only have 4AWD, 4HI, 4LO to choose from. and I'm always in awd unless the situation calls for 4x4.

 

[toms89]

Actually yes, the second time I switched into 4wd I was on dry pavement... So you're exactly right in how it should have acted. and I now feel dumb lol.. All tires are the same size too. So I guess the expy did its job.

But what I'm still confused with is why would It switch into 4hi by itself? Bad relay maybe? I have been driving since and everything feels normal. Just that one thing really freaked me out. Better to ask than to find out the hard way. BTW and I'm sure this is redundant to you guys.. but, I only have 4AWD, 4HI, 4LO to choose from. and I'm always in awd unless the situation calls for 4x4.

Should be A4wd, 4HI, 4LO.

It all depends on how you interpret it but these are not "All wheel drive". That to me anyways refers to vehicles that have some sort of differential between the front and rear drivetrain so it constantly receives power to all 4 wheels. A4wd means Auto 4wd or automatic 4wd. This works by engaging the clutch in the transfer case on demand which then applies power to the the front drivetrain. The pcm does this when it sense slip and varies the "on" time as necessary. Normally this set up is running in 2wd.

I personally feel "all wheel drive" is much better for the street as all 4 wheels constantly have power. It is also much friendly while turning due to the differential between the front and rear. But 4wd is better off road as you can lock both the front and rear axles to turn the same speed and you also have 4 low option. All wheel drives traditionally do not have this capability.

These terms seem to be used interchangeably now. But to me there is a basic difference in how they operate... A4wd vs Awd

Just my opinion and thoughts.

 

[Jcovill125]

Should be A4wd, 4HI, 4LO.

It all depends on how you interpret it but these are not "All wheel drive". That to me anyways refers to vehicles that have some sort of differential between the front and rear drivetrain so it constantly receives power to all 4 wheels. A4wd means Auto 4wd or automatic 4wd. This works by engaging the clutch in the transfer case on demand which then applies power to the the front drivetrain. The pcm does this when it sense slip and varies the "on" time as necessary. Normally this set up is running in 2wd.

I personally feel "all wheel drive" is much better for the street as all 4 wheels constantly have power. It is also much friendly while turning due to the differential between the front and rear. But 4wd is better off road as you can lock both the front and rear axles to turn the same speed and you also have 4 low option. All wheel drives traditionally do not have this capability.

These terms seem to be used interchangeably now. But to me there is a basic difference in how they operate... A4wd vs Awd

Just my opinion and thoughts.

I literally could not have said that better myself!

 

[eastmonsoon]

Have any of you experienced it shifting into 4WD from A4WD on it own? I am getting about 10 in the summer and half of that is highway miles. Just curious.