You could try removing the terminal from the connector and bending back the sides to expose the contact inside. Clean it up and then fold everything back together. Apply liberal amounts of dielectric grease before reassembling. See if that works. If not, then a new terminal has to be obtained somehow. Heck, even a junkyard terminal would work provided it isn't corroded too. Doesn't even have to be the same wire color.

 

Why dont you try removing the 4lo wire and see if the problem goes away. This would point you to the switch vs the connector. If you have a meter it is easy to test the switch resistance of each button. Its also easy to open up the switch if you find a problem.

 

tested the switch and all the readings are spot on. i looked through the schematcis and saw several wires refering to 4lo. which one specifically is it? on which module?

 

Have you tested for the same resistance readings at the appropriate pins (F14 & F16) in the TCCM connector?

 

So I made a bad. U cant pull the wire. There is only 2 wires that go from the switch to the TCCM. F14 & F16. So are you saying the truck will actually shift into 4LO or is it just the indicator light blinking. The 4Lo indicator lamp is F1 PPL/WHT wire. I would agree somehow the resistance the TCCM is seeing is not accurate if it is truly shifting into 4LO. U could also open up the TCCM and measure the resistance on the backside of the TCCM connector F14 & F16. Check if thats solid even when wiggling the connector. U will need tiny clip on leads

 

Yeah. With the NV236, there isn't a single wire associated with the 4LO button as there was in the NV233 switches. The TCCM supplies 8V to the switch and monitors the voltage returning on the circuit after it has been modified by the switch via the parallel resistors.

 

Ill try that. And yes my truck actually shifts into 4lo if i let it. All 4wd functions work. Jus the 4lo has a mind of its own. So f14 and f16 should read the same as the a and b on the back of the switch correct?

 

Yes. If they don't, then you have a wiring problem between the switch and the TCCM.

 

and the chase continues. checked the resistance on the backside of the tccm and all readings are good. so that tells me my wiring to the tccm are good. but does that also mean the tccm is not to blame. because its connection with the switch is good. correct me if im wrong but i think i have ruled out the tccm and the switch. but something that confuses me is that i read somewhere that the issues with hvac go hand in hand with the vacuum switch rite? my hvac keeps letting in outside air even with the recirc button selected. but ive already tried replacing the vacuum switch and it still doesnt work.....sooooo now what? lol.

 

I dont think you ruled out a bad TCCM. You ruled out the switch and the connection corrosion. So you actually opened up the TCCM and made the measurements at F14 and F16 on the TCCM pc board with the connector plugged in? I havent tackled the vacuum problems yet but I can tell you there are a few vacuum lines by the power steering and ABS that were totally disintegrated on my 99. One of them actually supplies that vacuum switch on the firewall. It tees off and a line runs into the truck. You might take a look at those hoses for your vacuum problem. I bought used TCCMs at the junkyard when I got to about where you are. I ended up buying and returning several TCCMs til I got one that worked. All of them had corrosion at the connector. The TCCMs get wet from the vent you said is not functioning. That vent is located just above the TCCM harness. You can see it thru your glove box.