I am having some isues when trying to switch from 2HI to 4HI. If I do it while driving nothing happens. If I put it in nuetral and hit 4HI the 4 HI and 4 Lo lights flash but nothing happens. If I shift to 4 LO it works everytime but not 4 Hi. The handbook indicates that I may need to have the Transmission Indicator Switch adjusted. Is this a major job? Living in Cleveland I really need to 4HI.

 

The only time that a transfer case shift would be restricted to neutral or park transmission positions is when a range shift is attempted (HI to LO or LO to HI). Going from 2HI to 4HI or 4HI to 2HI is not restricted in any gear, programming wise.

If you do not have the Auto4wd option, I would start by following the OBD2 Non-Automatic Transfer Case Diagnostics in the Tech Article (DIY) section.

 

Im a little confused. I have very little mechanical knowledge and usually only fix small things that I can handle. I do not understand the article you pointed me to but I can say this. I have a memoscan u381 ODBII scanner and when I hook it and run the diagnostics I do not see any error codes that point to transmission. I only get an 02 sensor error whih is not related to this in any way. Should I just take it to a shop and get an etimate? if so what do I need to watch out for?

 

Usually when you do not understand something, you ask questions to gain an understanding... Please be specific about what you do not understand and we will help you through it. It is difficult to explain something when we do not know what you do not understand.

The first part of my statement (prior to the link) is that if you do NOT have the Auto4wd option. If you DO NOT have the Auto4wd option, you then have a 3-button switch in the dash which corresponds with the NV233 transfer case. If that is the case, then you can use the information in the link above to check for codes in the TCCM. Since it is not a serial connected device, it cannot communicate with OBD2 scanners.

If you DO have the Auto4wd option, then you will have the 4-button switch in the dash which corresponds with the NV236 transfer case. The TCCM used in this system is a serial connected device which can communicate with scanners, however, the scanners must be appropriately programmed for GM enhanced data. Generic OBD2 scanners will not access this system.

 

I appreciate your understanding and patience. I have read the link again and think I get it now. When I get home I will try to steps listed in the link. I do not have the Auto4wd option