The dash switch is known to fail? I previous owner said that he had it replaced about 4 or 5 years ago, if not longer. Does the switch light up behind AUTO 4, 2H, 4H, 4L? I'm taking about the lettering not the indicator light. I think last year that my AUTO button was lit but not any of the others, but now none of them are lit. How would I go about testing this? Sorry for always asking how to do these thing but I am learning.

 

Don't worry about asking-the only way(or at least one of them) is top ask! Yes, those dash switches are prone to fail although I would hate to be in your shoes and buy one and have it not be it. In my shop, I service basically only Blazers/Jimmies and sell 95% only these so...I stock the switch and could try it and if not it put it back on the shelf for the next time. With you...well that may be different-not sure if you have any connection where it could be returned if not it.I'm sure there is a way to test and someone here may have the info but I have found, atleast for me, that it's not usually time effecient to check, test, repair.(although you may not be doing all those choices). I'm trying to save customers money which usually involves buy and try-but I've already bought it so...have you a buddy with one of these you could try and switchh? A junkyard near although you could get a bad one there also..Good luck-sorry about the longwinded answer to your simple question. JP[>:]

 

BTW-did you ever hook the battery cables together per my earlier post? I know it sounds 'backyard' mechanicish but it may work and I think where sometimes these systems go 8 months without being used sometimes if it can be gotten to work it may continue for who knows how long! JP[>:]

 

You can test the switch operation with an ohm meter. Here is a schematic for the transfer case shift control switch which shows the resistance values both base line and when pressing the individual buttons:


For the resistance, you have to use the parallel resistance formula:

In this case, there are only two parallel resistors when only one button is pushed.

The resistance between connector 1 pins A & B are as follows for single button push:

• No buttons pushed - 9.09kOhm (9090 Ohm)
• 4Low pushed - 2.345kOhm (2345 Ohm)
• 2High pushed - 1.516kOhm (1516 Ohm)
• 4High pushed - 0.663kOhm (663 Ohm)
• Auto4WD pushed - 0.064kOhm (64 Ohm)

For multiple buttons pushed at the same time you would need to expand the formula above and find the equivalent resistance for the circuit.

Just for others that take a look at this thread later on, this is for the Auto4wd (NP8) NV236 transfer case shift control switch only. The NV233 (NP1) transfer case is a direct connection with dedicated wires for the different modes and is easier to test.

 

JP - I tried that backyard stuff I left it there for over 5 minutes while trying to find the right size wrenches for the battery terminals.

Kyle - So I connect the multimeter up to PIN A & B on the schematic? I see A that goes to the IP FUSE BLOCK, but where is B? And the second pic is not showing up.

Is there lights behind the the buttons? Not the indicator lights but light so I can see what button I'm pushing, because I push the button and it his kind of a feel and hope I'm pushing 4H not 4L.

 

You are looking for the pins that connect to the light blue wire (Pin B in connector 1) and the light green with black tracer (Pin A in connector 1). Look at the label "Transfer Case Shift Control Switch" and then look just to the left of that for the "AWD", "4H", "2H", and "4L". Follow the traces to the lower part of that box and you will see the wire colors for the wires associated with pins A and B on connector 1.

 

Ok let me make sure I got this right. I hook up my multimeter up to the light green w/ black wire and the light blue wire. With no buttons pushed (which would be in Neutral) I should have 9.09K Ohms. With 4H I should be getting 2.345K Ohms and so on with the rest of the buttons. These wires should be right behind the 4X4 switch on the dash right? And I want to thank you guys for all of this information your throwing out there for me I am so glad you have the knowledge that some may lack and helping out!


EDIT: As I am looking at the schematic for this I notice in the "Transfer Case Shift Control Switch" all the way to the left it shows two bulbs that say Illumination Lamps, would this be the lights inside of the TCSCS that illuminate the the push buttons them self, the back light?

 

You need to disconnect the electrical connection and hook the multimeter up to the pins in the switch that correspond to the wires mentioned. So look at the plug on the switch with the connector disconnected and find which pins get connected to the light blue and the light green with black tracer wires. Then you can connect the multimeter and test resistance. You cannot test resistance with the wires connected.

And yes, there are bulb in the back that should backlight the switch.

Just thought I would throw a link to THIS ARTICLE as well. It is for the NV246 which is the big brother to the NV236 used in the s-series trucks. RSGear.com has a lot of tech articles on the New Venture/New Process/Borg Warner transfer cases.

 

So I was going to test the selinoid on the firewall today but when pulling the bottom vac hose off the nipple totally cracked off! I went to the dealer to get an new one and installed it and still no 4wd! There goes $60 on a part that wasn't even the problem, I'm so frustrated, mad, annoyed, and many more. My money right now is on the 4x4 dash switch. I'm about to go out there in this 30* weather to test the resistance of the switch, or can I just pull if off and test it inside the house?

 

Definitely pull it off and test it in the house.