Have a 2005 gmc envoy xl slt 4.2 lt when you put 4x4 into 4 hi or 4 low you can hear electrical switches and hear and feel like it is in 4x4 the front drive shaft locks up but front wheels stay like they are in 2 wheel. Took to gm dealer and they ran a scan and said things were fine electrical but for some reason the 4x4 is not engauging

SOURCE: 2002 gmc envoy slt 4x4

Had the same concern. Had to take mine to the dealership and have them replace the system. Be careful when you change between the drives. Vehicle MUST be in park, of course started, and you can change the drive. WAIT until the light completely stops blinking before placing into gear or trying to change to another setting. When you change the setting, a gear arm raises or lowers, and resets. Listen and you can hear it. Often when the vehicle has sat for a while, or if the battery has been disconnected, you will hear it resetting. If this does not work, you have to take it into the shop to have the gear sensor repalced.

SOURCE: replace starter on 2002 GMC Envoy SLT

check to see if the starter itself is getting a signal to crank. youll need to use a test light and have someone else try to start the vehicle, while you probe the wire to the starter to see if it is getting power. if not, check the starter fuse to make sure its not blown, as well as the starter relay to make sure that is good too (very common on gm's for bad relays) if the fuse and relay are good, but your not getting signal, it is an ignition switch problem.

Dan De Groote

• 35 Answers
• Posted on May 26, 2009

SOURCE: need fuse box diagram 2002 gmc envoy

If I remember correctly if you look at the back side of the fuse cover, it should tell you what the fuses are. Also in the owners manual in the index, under fuses, it should give you a diagram of the fuse location for the acc. outlets. Good luck. The fuse should be a 20 or 25A fuse.

SOURCE: 2002 GMC envoy SLT 4x4, tccm, switch problem

About 45% of all transmission problems are due to a defective battery, its components and the charging system. Make sure you have the correct battery in the vehicle and inspect all items relating to the charging system and the battery. The vehicle should charge between 13,5 to 14.5 volts. The condition of the belts is part of this inspection. If all of this is A-ok then get a scanner and pull the codes in the PCM.
Remember once light is illuminated for a item that item no longer works. Once you've gotton to this point let me know and I'll walk you threw it. Hopefully its just a weak or incorrect battery or something along those lines. Good luck and keep me posted

SOURCE: will not go into 4 wheel low

Make sure you have it in (N) before shifting it. Did it work before?