4wd auto and 4low lights flashing

[Diff Whack Daddy]

Okay, I am new to the second gens, but have vast experience in the 1st gens. I have just aquired a 1995 Explorer with the switch labled 2wd/4wd auto/ and 4low. Here are the symptoms

While stopped with the tranny in nuetral and the foot on the brake. Switching from 2wd to 4wd auto, I can hear the shift motor move, but the only indication I get on the dash is a series of flashing lights, 4wd auto and 4low.

Turning the nob to 4low gives me the distinctive engagement clunk and is confirmed with a quick test in drive to prove I am in 4low, at least on the rear axle.

So, basically, that tells me the shift motor on the t-case and the switch are properly connected. PLEASE CORRECT ME IF I'M WRONG.

So what is my next step. From SEARCHING, I am going to check the vacuum lines for the axle disconnect for cracks, but after that, I am kind of stumped. Is there any other way to troubleshoot this other than the scan tool at the stealership?

 

[Glen4X4]

Actually in 2wd your transfer case is in 4high gear its only that in 2wd the front axle is in the disconnect position when switching to 4auto your connecting the front axle and allows for the automatic 4wd to take place you can switch to 4auto on the fly. Not sure on the lights flashing but I "thought" that was an indication of a bad speedo sensor.

 

[Diff Whack Daddy]

I am pretty sure that in the 2wd position, the front driveshaft is disconnected in the transfer case, just like in the 1354 transfer cases. Again, somebody please correct me if I am wrong.

 

[Glen4X4]

These transfer cases only have 2 gear positions. It is a torque on demand t-case so its only in 2wd until the clutch coil in the transfer case gets power then it drives the front drive shaft. In 4auto your essentially in 2wd until your rear wheel slips then it engages briefly.

 

[Albino 94LTD]

Maybe this thread has the answers?



http://www.explorerforum.com/forums/showthread.php?t=10166

 

[Diff Whack Daddy]

Maybe this thread has the answers?
http://www.explorerforum.com/forums/showthread.php?t=10166

Apparently the 95-96 control trac is different than the 97-01 control trac. In 95 and 96 they used a center axled disconnect (CAD) system to disengane the right front axle. Therefore, my system has more moving parts. So far, I have figured out that I need to test the CAD to ensure that it is locking the right front axle, then move on from there. Somewhere the GEM module is either not getting the proper input signal or the GEM is bad. I will start with the CAD, then clean all the sensors and shift motor contacts, and then the old ratheon reset on the battery. If all that fails, I will pay the diagnostic fee to have the dealer tell me the problem, then source and replace the parts myself.

I have ran in to this before on the F-350 where a secondary scan tool that costs an arm and a leg is needed to do the diagnostics.

 

[35Remmy]

Last time my lights were flashing I disconnected the battery for 5 minutes...problem solved.

 

[Diff Whack Daddy]

Well of course I'll try that first.

 

[Diff Whack Daddy]

Okay, so the battery disconnect, wait, reconnect fixed the light problem, but I also noticed that the front tires did not spin in opposite directions as the troubleshooting indicated they should, nor did they spin in the same direction. This leads me to believe that I have a problem with my CAD.

What are the troubleshooting procedures for that?

 

[gijoecam]

Got your PM this morning, but figured I'd just reply here....

As you seem to have figured out, the problem lies with the CAD. You have a couple of options... the easiest long-term and headache-free solution would be to swap in the front axle from a 97-01 sans the CAD, and cap the lines at the solenoids. There might be an electrical issue with the GEM waiting to see the CAD engaged switch being made, but that could be bypassed with a simple toggle switch.

To deal with the CAD itself, I'd first check to see if you're getting the proper vacuum signals ot it. Engine idling, you should have vacuum to one line in 2wd, and the other in 4high or 4low. You should never have vacuum on both lines at the same time. It's also possible that one of the lines is broken or leaking, so some tube-running could be in order.

If that's not it, then it could be the CAD itself. Quisman was having a similar issue with his in this thread... Might be worth perusing. But it's pretty simple mechanically-speaking. I'm sure you can figure that part out without any trouble.

This is all, of course, assuming that the t-case is actually engaging. Lock it in 4low and see if the front driveshaft is also locking to the rear. Idling in drive, it should lock the front shaft. If it doesn't, there could be other issues...

 

[Diff Whack Daddy]

Well I finally got some time to trouble shoot the CAD today. Turns out the CAD was fine. I applied vacuum to it and sure enough it engaged and disengaged properly.

I then checked vacuum at the vacuum switches. They had source vacuum from the engine, but were not switching. My first thought was the GEM, but I decided to go a little more basic and check fuses. Luckily the Chilton's manual I have for my 91/93 goes all the way up to 97 so it had the fuse block diagram in it. I started by checking the fuse in the main distribution block under the hood, good. Next I went to the passenger compartment panel and checked every fuse that said 4 wheel drive or GEM. When I got to 26, it wasn't there. Instantly I though hmm, could this be the whole problem? While looking for the spare fuses, didn't know they were on the door the was sitting on the floor board, I noticed that there was a fuse in spot 30, which is not used. So I pulled it and stuck it in slot 26 and everything works great now.

What I don't understand is why somebody would have pulled that fuse and put it into an unused spot. Maybe time will tell.

 

[Tbars4]

...Congrats on the cheap fix...

...I wish they were all that cheap...