4wd neutral light

[klittle1417]

So here's is the scenario...1999 K1500 suburban 5.7 with auto 4wd..4wd worked fine, I plowed a drive way last night then came home. Parked for a couple of hours then went out to move the suburban. Was in ice so I tried to use 4wd. The neutral light is on as well as 2hi and 4lo. 4hi won't engage. No flashy lights just nothing.

Thought it may be the switch so I got a new one and just installed it. Still the same thing except 4lo isn't illuminated.

What say you experts? Was working normally then suddenly not. Also, it's been wicked friggin cold in Maine but it worked at first.

Thanks in advance for any help.

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[df2x4]

Are you switching the transfer case while the truck is in gear? While that will work for 2HI/4HI, in my experience you have to shift to neutral (not park) to engage or disengage 4LO.

Probably no help, but it pays to check the easy stuff first.

 

[klittle1417]

I can't get 4hi while sitting still.

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[df2x4]

Gotcha. My guess would be the actuator since you've already replaced the switch, but I'm sure someone with more knowledge on the subject will chime in.

 

[L29Sub]

You likely resolved this issue but...if not. Problem's likely the encoder motor. They become intermittent early when failing. Another common enough issue is water incursion into the TC encoder wiring connectors and bad grounds. Cold weather screws with old T-cases.
Simple fix (more or less?) Is install an NP241. 94 to 99 NP241will bolt in where a 243 or 246 lived, and VSS speed sender will be correct. NP241 was used thru 2000...but 99 and 2000 k1500 is quite different. A bit of research might be in order on fitment. Similar year model doner will give correct driveshafts and shifter too. You'll need to have the ecm remapped, but the truck will operate OK without mapping.
If you determine that the encoder is faulty, and decide to replace same ....avoid those eBay cheap encoders. Replacing an encoder must be done per instructions.
243 and 246 T-cases were known for this cold and wet intermittant crap.
I changed my 246 out for a 241 (99, BB, k2500) for the reason you describe. It would work all damn summer and when cold weather set in it became a crapshoot....then it would start shifting normally...problem solved with manual case! Installed an NV3500 with an NP241C. NO problems since. Added a control switch in the dash for front axle lock. However, the T-case will control the front diff if . A good 241 can be found for $150-250 bucks. Often have shifter assembly with them.
All 4x4 GM 4l60e, 4l80e, NV3500 and 4500, 94-99 old body style will accept an NP241, and all have 31 spline output shafts.
I'm