There are a total of 5 detection switches on the transfer case. one is a neutral detection switch (operates briefly between high and low range). one is for 4wd detection, one is for 4wd operation, one is for center diff lock detection, and one is for center diff lock operation. basically, there is a switch that detects that you want it in 4wd, and then there is a switch that lets the ecu know that is successfully switched into 4wd. likewise with the center diff lock. there is a switch that detects when you push the stick into position to lock the center diff, and then there is a switch that lets you know when it actually successfully locks. just make sure all the plugs are plugged in correctly, (brown plug to brown plug, white to white, and black to black) all plugs are identical, and they will plug into each other in correctly (i.e. black to brown will fit, but will result in an incorrect circuit and the lights will act funny). if your t-case was working fine and then it just started acting up recently I would suspect that a switch came loose, a wire is cut or pinched, or if you had work done on it recently, the mechanic messed up something. when I had my t-case gears swapped out with 3.15's, the gear shop let one of the little steel balls that is supposed to sit right under each switch fall to the bottom of the case. when I changed my gear oil, it came out with it. I re-installed it accordingly. the switch it was missing from was the neutral detection switch, which you hardly even notice if it's working or not since your t-case is almost never in neutral. anyway, the switches are round with one wire coming out of them. you put a wrench on them to tighten or loosen them.

Here I figured a way to upload the pics

So these black tops are the switches





here are the connectors
and they are connected accordingly(white to white, black to black & brown to brown)




thanks again for the info <img src="/forums/images/graemlins/kewl.gif" alt="" />

Witht he help of this I found the 5 switches and connectors







and the info on this web page http://4wd.blogeasy.com/

in total, there are really 6 switches, the 6th one is at the very rear of the case next to the speedo sensor/harness. that sixth switch is the low range operation detection switch. it is different than the other switches b/c it doesn't have a hex head on it that you can put a wrench on to remove it. it has a white connector that connects at the top of the case with that group of 3 connectors. there is continuity through the switch when in 4low, and no continuity in any other position.

3 more switches lie at the top of the case kinda in the center of the case. there is a poppet plug (looks like a switch just no wire coming out) in the same area as these 3 switches and when viewed from the top, all 3 switches and the poppet plug form a square. one of these 3 switches has a white connector as well (different white connector than the 4 low switch at the rear of the case). this switch with the white connector does not connect to the white connector at the top of the case right next to it like you would think, rather it connects to another white connector more forward on the t-case and much lower (kinda on the driver side side of the case). this is your high/low range detection switch. this switch has continuity through it in all positions except when the t-case is in neutral (between 4high and 4low). I like to think of it as the neutral switch. the second switch out of the 3 at the top of the case has a black connector that connects to the black connector right next to it at the top of the case in that group of 3 connectors. this is your 4wd operation detection switch. it has continuity in 4h but not in 2h. the third switch out of 3 at the top center of the case is your center diff lock operation detection switch. it has a brown connector that connects to a brown connector right next to it in that group of 3 connectors at the top center of the case. it has continuity in 4hlc but no continuity in 4h.

more towards the front of the case the remaining last 2 switches lie. one has a black connector that plugs into a black connector right next to it and the other has a brown connector that also plugs into a brown connector right next to it towards the front of the case. the one with the brown connector is your center diff lock detection switch and just like your other brown connector switch at the center of the case(center diff lock operation detection switch), it also has continuity when in 4hlc but none when in 4h.

so basically to sum it up, your 2 black connector switches are for 2h/4h detection/operation. your 2 brown connector switches are for center diff lock detection/operation. and your 2 white connector switches are for high range/low range detection/operation. notice how they are in pairs, one switch detects that you want it to shift and the other lets you know that it has shifted and is in operation. for example, when you move the t-case lever from 2h to 4h, the lights start blinking to let you know that you have shifted into 4h. this means that the 4wd detection switch has been switched by you moving the t-case lever. the lights will continue to blink until the 4wd operation switch is shifted by a moving mechanism within the case itself. so basically one 'detects' that you want something, and the other lets you know when you have operation of what you 'wanted' it is a very clever system that gives you a lot of info about what is going on within the case. now, with the 4wd mode, there is also another detection switch in the front axle free-wheeling clutch assembly, this has nothing to do with center diff lock or anything going on in the t-case, but I wanted to throw this info out there. that front axle switch also gives info to the computer to let it know when the passenger side cv axle is fully connected to the differential assembly via a free-wheeling clutch assembly that operates on the engine vacuum system with solenoid valves. even though the t-case is ready for 4wd operation and the front output shaft to the front diff is providing torque, the front axle is still going to be 'static' (meaning that the spider gears within the front diff are spinning against themselves as each cv axle turns but does not turn the ring gear) until the free-wheeling clutch actuator moves over and connects the passenger side cv to the diff.

tell me more about your problem, when you are in 2wd, just your center diff light blinks? what about when you are in 4h, does it still blink? what about when you are in 4hlock, does it blink then? what about when you are in 4lowlock, does it blink then? if it stays on constantly when in 4hlock and 4lowlock then your operation switch or detection switch for the center diff lock could be stuck closed even when in 2wd. more than likely it would be the detection switch before it would be the operation switch, but it could be either switch with brown connectors, there are two in total. let me know what is going on with it, if everything 'feels' like it is working fine, then it is either a switch, wire, or connector somewhere. I want to identify what it is before I tell you what I think you need to take apart.

ok, before we go any further, you haven't told me if you checked the level and condition of the gear oil within the case???? for example, if it is low, you may want to drain and replace it. when you pull the plug you may find metal debris which may indicate internal damage. I don't think internal damage is the issue as long as you didn't experience loud grinding or popping from that area of the truck. if it is low on gear oil, I would fill it to specified lever first to see if that solves the problem. remove the t-case skid plate and look for a 15/16" plug half way up the case facing the rear of the truck on the driver side of the case. that is your fill plug. the level of gear oil inside the case should be right in line with the bottom of that hole in the t-case, if oil doesn't seep out when you remove the plug on level ground, then fill it until it seeps out slowly. then it is filled to proper level. you must check the gear oil lever first b/c wiring or switches could be just fine the way they are.

oh and by driver side, I mean left side as you are sitting in the truck, don't want this to be confusing if you have a right hand drive truck. mine is a left hand drive meaning the driver side is the left.

Hey Scott

Sorry havn't replayed sooner

Anyways: the system feels like it is working right(because I tried it locking and unlocking the diff)

the c/d diff light keep blinking in 2H and in 4H. When I lock the diff the light becomes solid in 4HLc and 4LLc.

I had the front indicator blnking issue solved last year, the problem was a bad control solenoid keeping the front wheeling clutch enganged at all times resulting the blinking front tires indicators

I still havn't got the time to check the level yet <img src="/forums/images/graemlins/scared.gif" alt="" />,(busy with work, thats why I replayed late)

yes, check your fluid level first, if it is low, could be causing a switch to stick or something. if fliud is ok, then unplug one of the brown connectors and drive the truck. let me know how the lights behave. then re-plug that same brown connector and unplug the other brown connector and drive it to see how the lights behave. let me know and we will go from there.