Four-wheel drive

[bsamoul]

Four-Wheel Drive Blinks!

Ok, so after reading a couple posts about people's four wheel drives, here's my case. Neither 4 hi or lo will stop blinking on my switch, no matter how long I have it on. I removed fuse 2 for 5 minutes and put it back in because that's for the transfer case, but nothing. It kind of feels like it is working though because there is more power distributed to the front. When I click 4lo, there is a big metal clunk as if it is force engaging. What could be my problem? I'm going to need 4wd this winter up in Tahoe. TIA

 

[bsamoul]

I've also read around and found that it could be the actuator. Only problem is, is I'm not really quite sure where that is. And how do I know if I have the thermal sensor or not?

 

[loulblades]

The actuator sticks out the passenger side of the front differential. It is screwed into the diff and is pretty easy to get out.

The thermal actuator diff has a 2 pin connector above the actuator. Refer to TSB 76-43-01A for more info.

To listen what is engaging (or not) have someone press the button while you listen underneath. Key only needs to be in the ON position. Not that I haven't laid on the ground under a running truck but I try to avoid it when someone is changing the controls.

As I said previously, you should hear the motor on the transfer case and the front diff actuator.

Since you are hearing a "clunk" then most likely the transfer case is engaging since it would be difficult for the front actuator to engage otherwise unless someone bypassed the transfer case switch or it is shorted.

If I recall there are 2 fuses for the 4WD system.

 

[bsamoul]

Should I take the skid plate off or can I hear it with it on? And is it loud or what should happen? I'll check the fuse box again in the morning to see if there is another fuse to look at. I drove with it supposedly on today but couldn't tell if was actually on...

 

[loulblades]

I don't need to remove my skid plate to see the front differential.

 

[bowhunter22]

After the big CLUNK when 4low is engaged and you put it in gear do you have low range? If so then the transfer actuator is working. As for the blinking light you need to figure out if the slide collar in the front axle is engaging. If you have 4x4 to the ground then it is a bad proxy switch not telling the control that it is in position.

 

[bsamoul]

After the big CLUNK when 4low is engaged and you put it in gear do you have low range? If so then the transfer actuator is working. As for the blinking light you need to figure out if the slide collar in the front axle is engaging. If you have 4x4 to the ground then it is a bad proxy switch not telling the control that it is in position.

I'm pretty sure 4lo works because if I put it in drive after there is a lot of torque, so that has to mean it's working right? If it is the proxy switch that isn't working right, does that make too big a difference since it is working? I'm still not sure about 4 hi if it's working or not..

 

[loulblades]

I'm pretty sure 4lo works because if I put it in drive after there is a lot of torque, so that has to mean it's working right?

This would indicate that the transfer case is engaging but, in itself, doesn't mean the front diff is.

If it is the proxy switch that isn't working right, does that make too big a difference since it is working? I'm still not sure about 4 hi if it's working or not..

If it is the proxy switch (thermal actuator) or the contacts (motor actuator) and the system is engaging (transfer case and differential) then as long as you can put up with the blinking, no problem. So either the front actuator isn't engaging or the controller is not receiving feedback that it is.

I have an updated controller board that will return to 2WD if it doesn't see the system engaged in 5 seconds so mine couldn't do what you are suggesting (running with the blinking). If I recall, with my older setup (thermal) the light would continue blinking. I don't think there was a time limit because in cold weather the actuator took longer to engage.

 

[bsamoul]

Ok, so I brought it into the dealer today. They said they need to replace the front actuator and service the system. It would have cost $600. How much, and where can I get an actuator from???

 

[loulblades]

The dealer or the local parts store.

 

[loulblades]

BTW replacing the actuator, if you are using the same type that you have, is about a 10 minute job. Unplug it, unscrew it from the differential, screw in the new one, plug it back in.

$600 seems a bit hefty since the actuator itself is in the $90 - $150 range depending where you get it, but then again I don't know what is included in the "servicing". If you are upgrading from a thermal unit a wiring harness would also be included, which pushes the price up some, and that would require some cutting and splicing of wires.

 

[Hoosier Zephyr]

I have the same thing happening to my 96 2 door. I went and listened to it, it sounds like it was trying to engage. How can I tell if the actuator is bad. Is there anything else it could be?

 

[bsamoul]

BTW replacing the actuator, if you are using the same type that you have, is about a 10 minute job. Unplug it, unscrew it from the differential, screw in the new one, plug it back in.

$600 seems a bit hefty since the actuator itself is in the $90 - $150 range depending where you get it, but then again I don't know what is included in the "servicing". If you are upgrading from a thermal unit a wiring harness would also be included, which pushes the price up some, and that would require some cutting and splicing of wires.

So I just replaced the actuator, and still nothing. It gets really warm, but I don't hear anything coming out of it and the light continues to blink. Any other idea?

 

[loulblades]

You said it gets "really" warm. If this were a thermal actuator it would get warm but I recently read that thermal actuators are hard to come by.

Notice if there is a 2 pin connector above the actuator sticking out of the diff and if there are wires connected to it. If there is, that would be indicative that you are still using a thermal actuator. Also how many pins were on the actuator connector?

If the actuator is getting warm when you select 4WD, this would indicate the transfer case switch is operating. Have you determined that you have 4WD (either by getting all wheels off the ground or gunning it in some snow) or not? The blinking when you select 4WD is an indicator that the control module is not sensing that you are in 4WD, whether you are or not.

Ok so if you have a motor actuator can you hear it engage when you select 4WD (you pretty much have to be standing at the front of the vehicle so you not hearing the transfer case motor)? If it is the motor type and it is getting "really" warm when you select 4WD, your diff may be locked up in the disengaged mode. Haven't seen that happen but certainly could imagine it.

 

[bsamoul]

You said it gets "really" warm. If this were a thermal actuator it would get warm but I recently read that thermal actuators are hard to come by.

Notice if there is a 2 pin connector above the actuator sticking out of the diff and if there are wires connected to it. If there is, that would be indicative that you are still using a thermal actuator. Also how many pins were on the actuator connector?

If the actuator is getting warm when you select 4WD, this would indicate the transfer case switch is operating. Have you determined that you have 4WD (either by getting all wheels off the ground or gunning it in some snow) or not? The blinking when you select 4WD is an indicator that the control module is not sensing that you are in 4WD, whether you are or not.

Ok so if you have a motor actuator can you hear it engage when you select 4WD (you pretty much have to be standing at the front of the vehicle so you not hearing the transfer case motor)? If it is the motor type and it is getting "really" warm when you select 4WD, your diff may be locked up in the disengaged mode. Haven't seen that happen but certainly could imagine it.

When I was testing it, I had my friend in the car hitting the button. I had my hand on it too to see if I could feel it moving. What I did notice while driving and seeing if it would work, is I feel a power shift. I would be accelerating and I could feel power moving. Another thing I noticed, was that when I hit the switch with the car off, I heard the relay under the dash and also under the car I heard something else moving that sounded kind of like an electric hole punch (if you've ever heard one).

Would trying to get a video and capturing the sounds be helpful at all?

 

[loulblades]

When I was testing it, I had my friend in the car hitting the button. I had my hand on it too to see if I could feel it moving.

If it is the motor type you will hear a motor running. A thermal type will get warm and you should hear some mechanical movement.

What I did notice while driving and seeing if it would work, is I feel a power shift. I would be accelerating and I could feel power moving.

I am not sure exactly what you mean

Another thing I noticed, was that when I hit the switch with the car off, I heard the relay under the dash and also under the car I heard something else moving that sounded kind of like an electric hole punch (if you've ever heard one).

The clicking you hear inside is the TCCM (transfer case control module) mounted on the steering column. As I previously said, the sound from underneath is the transfer case encoder motor.

Would trying to get a video and capturing the sounds be helpful at all?

Probably not since everything sounds right except for the proper operation of the actuator. Of course you could setup a camera and record stepping on the gas in 4WD in snow and see if the front wheels spin.

 

[bsamoul]

What I mean by the power moving, is it really feels like some power is shifting from the rear to the front. It isn't much, but I do notice something.

 

[heveymetil]

Hi all...

I've been having the same problem(s) as described by Bsamoul....my 4 hi and 4 low constantly BLINK everytime I try and engage the system. I, too, can hear clunks and clanks as if it's "working" but NO power to the front wheels...whatsoever. I've had the actuator replaced once last year, which was okay four about a month this winter...go figure.

The "good" news is that I don't have a garage and the ground is freezing - 0F today - so I took my 'hoe in to a local shop to diagnosis. I'll let you know what happens and we can compare results...

...also....I'm a newbie...be gentle!

WAT

 

[loulblades]

What I mean by the power moving, is it really feels like some power is shifting from the rear to the front. It isn't much, but I do notice something.

When the transfer case engages, you might feel a slight change since power is now being provided to the front differential but that doesn't mean it is making it to the ground. The front differential actuator and the engaging of the differential determines that (also assuming that the shaft to the front differential is intact).

I think we previously determined that your transfer case is engaging since you could feel the difference in gearing when you put it in 4WD Low.

 

[bsamoul]

Hi all...

I've been having the same problem(s) as described by Bsamoul....my 4 hi and 4 low constantly BLINK everytime I try and engage the system. I, too, can hear clunks and clanks as if it's "working" but NO power to the front wheels...whatsoever. I've had the actuator replaced once last year, which was okay four about a month this winter...go figure.

The "good" news is that I don't have a garage and the ground is freezing - 0F today - so I took my 'hoe in to a local shop to diagnosis. I'll let you know what happens and we can compare results...

...also....I'm a newbie...be gentle!

WAT

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