Transfercase problem!

[checkedout]

What should I do next? Here's the story. The transfercase went bad so I had it replaced about 3 1/5 months ago. The other day I noticed the 4wd & 4hi lights flashing on the dash. The 4wd system still works but something must be going! Any help?

Thanks
Pete

 

[TPLYNCH]

Might be a problem with the speed sensors.....

 

[checkedout]

Could that be an intermittent problem? I have been looking at some of your old posts on this very subject but mine seems to be working fine. It's not getting stuck in 4wd as far as I could tell. Should I have the computer scanned for a code? Snows gone for now. I'll check it out a lot better next time though.
Thanks
Pete

 

[checkedout]

I tried it again last night when I left work.... now when I put it in 4wd auto it locks into 4hi. I notice aquite a few posts with this same problem. Did anyone fix it yet? Was it the speed sensors? Is that something for the do-it yourselfers?

 

[TPLYNCH]

I believe the sensors are on the T/F case. Crawl under the truck and make sure all the wires/connectors are still plugged in. Sometimes they'll pop loose and cause the problem. If they are fine, then its probably the sensors themselves. Not sure about how to replace.... Also, the flashing lights represent a code, so you can always have that pulled to determine the exact problem the system is having.

 

[checkedout]

Thanks Tom. I looked in my Haynes manual, it shows one speed sensor behind the transfercase damper. I'll check the connector. Hope that's all but thats not how my luck usually works! I'll call around for a price on the sensor.

 

[checkedout]

Can I retrieve the code with a scan tool? Has anyone done this? It looks a little tight getting into the sensor. Advice anyone?

 

[checkedout]

Could someone tell me where I can get the sensors online? I checked a couple places but can't seem to find a listing for them. Are they both the same?

 

[TPLYNCH]

You can try Torrie at FordPartsNetwork.

 

[slow-demon]

The speed sensors on the transfer case are as follows. The frt output sensor is located behind the 4x4 shift motor, held on by a bolt, and monitors the frt driveshaft speed. The rear output speed sensor is located on the extension housing of the transer case and monitors rear output speed (rear driveshaft). Chances are one of the sensors is either contaminated or defective. The only way to figure out exactly which one is bad is to hook up a scan tool and watch the speed sensors and see which one is not working. With one sensor bad and not giving the correct reading the ford GEM module is thinking that one of the tires is spinning and is activating the 4x4 automatically which is what it is supposed to do when the system is working correctly. I would try to get a scan tool or get it in to ford for a diagnosis. The sensors are easy to change and you should also change the fluid since there might be something contaminating the sensors. You could also try taking out the sensors and cleaning them.

 

[checkedout]

Thanks for your help guys. I'll let you know the results when I get it done.

 

[checkedout]

I've got the sensors from Torrie. I'll put them in this weekend, do I need to drain the case first?

 

[Robert]

I can't remember if the speed sensors are above the fluid or below for sure, but from what I remember when I removed mine they were right at the fill level. You won't loose all of your fluid though when you pull them out since they aren't at the bottom. I removed mine at the same time that I replaced my transfer case fluid so I drained it first. My '97 manual calls for a fluid change every 30K miles and it actually went smoother than an oil change (less messy) so you might as well go ahead and do it to. It only adds a few minutes and all you need to buy is two quarts of Ford Mercon ATF.

Regarding your question about whether or not a scan tool will read the codes for your flashing 4x4 lights, the answer is not unless you have a Ford NGS Star tester or equivalent. I do know my $450 AutoXray scanner will not read them since they are a Ford specific code that most consumer scanners are not capable of reading.

If the speed sensors do not fix your problem, a faulty transfer case shift solenoid will also cause the same symptoms you are seeing. The solenoid is a worm gear that shifts your transfer case into low range when activated. When it fails you won't get Low and will get flashing 4x4 lights.