4lo engaging by itself
 

i have a 2001 blazer 4 button. my 4wd is constantly trying to put itself into 4lo. the 4lo light flashes while i drive or when im parked. i tried replacing the vacuum actuator on the firewall and it solved nothing. i dont wanna throw more money at the problem with no results. oh yea and all the other functions of the system work but its very difficult to get it to any other setting when 4lo is saying otherwise. can anyone shed some light on my problem please? thaaanks

Have you checked the TCCM connector(s) for corrosion or tested the switch resistances (NV236 switch resistance is covered in the Tech Article section)? Either could cause a resistance reading consistent with a 4LO selection even though the 4LO button has not been selected.

So i unplugged the tccm and pin f16 is corroded. (4wd switch selection signal) im guessing this is my problem. can i use dielectric cleaning spray to clean it or will that damage the tccm and corresponding plug? btw thanks for the help

That would definitely be a contributing factor. You can use electrical contact cleaner, but it may not be enough to get the connection back within spec resistance. If the corrosion is really bad on the female terminal, you may have to replace the terminal. To clean this without pulling the terminal from the connector, a small brass pipe cleaner can be used.

ok so i used the contact cleaner and no luck barely made a dent in the corrosion. i may just buy a whole new connector but im having trouble finding one online

You can buy just the female terminals from your local NAPA or online. Much more economical & easier than replacing the whole connector! I'll see if I can find the part numbers sometime today.

thanks a lot man. i appreciate ur help with this.

The 32 pin connector is a micro-pack 100 with female terminals.

Delphi 12146447 - 20/22 gauge Micro-pack 100 female terminal - $0.19 each w/ minimum buy of 5 pieces from PCS Connectors and a minimum order value of $10. You may want to add in a micro-pack 100 terminal disconnect tool (if they have it) or something else to get the value up to over $10 before shipping & handling (S&H was $7.65 for priority mail to my location). Good prices if you have more than one thing you want to buy or need them in quantity, but unless you want to hang on to 53 of these (to get over $10), it really isn't that great of a deal.

The GM part number for this terminal is 12084913. Expect to pay $3-$4 at a dealer parts counter for this part and it will likely come with 2 in the package.

NAPA has a PN for this as well, but availability is spotty. They have to buy it in boxes of 50 and rarely move these connectors. I was lucky to find the Metra-pack 150 female terminals when I added footwell & glovebox lighting to my Tahoe. You might get lucky so it's worth a shot looking through their connector catalog

More importantly find your water leak. Just burned my TCCM. Seems to be water coming thru the recirc vent via the vent air intake.

So i went to napa. No luck. Went to the dealership. They dont carry the terminals and the harness is over 100 bucks. I guess my next option is to buy a handful of them online. Im just sick of this headache that is my 4wd system. Lol