First a story from a friend of mine...and yes there are other symptoms besides what is listed in the bulletins below...stalling/no crank no start/gauge displays going wacky etc
The WOW test he refers to is when the key is turned prior to trying to crank the engine the gauge needles and all idiot lights cycle...
Also the specifics for replacing the ignition switch varies model to model and year to year...
Finally keep in mind his "how to" involves a Montana NOT a Terrain or Nox...but the location in Chevys is fairly common on the steering column...usually 2002 and prior are located lower on the column and don't involve the Air Bag and 2003 and newer are located in conjunction with the lock cylinder and involve putting the Air Bag in "safe mode" first.
"By far the most common concerns written on ro's is..."my gauges (or gages...lol) go to zero and then come back up to normal," or my truck has no power when pulling away from a stop and my check is light is on. These are the most common concerns for us by far.
I just replaced a ignition switch on a Montana today for a no crank. so like everything elese there are exceptions to the rule.
Now to test.. this can be hard for the guy who has no info such as service manual, it requires checking the power flow from the ign switch using a wiring scmat, the most common is the trans in 2nd and the ses light on(cause the trans sets power loss related dtc's due to the ckt being open(no power) use a test light at the trans fuse, no power at both sides and assuming the wiring harness is ok(never had a harness cause this) you can bet the ign switch is bad. also i catch many intermitent concerns by starting the truck and just wiggling the key around and watching the gauges for drop out, or watching my test light light that i have connected to the trans fuse, if the test light goes out or the gauges drop out while i am wiggling the cylinder then i know the switch is bad. another way i test is turn the key on/off many times hard and fast while watching the gauges, if i know i had the key on and the gauges didn't come up then i know or if the "wow" test ( the bulb check) fails to perform its self test then its the switch. again the most popular concern is either no power from a stop or my ip is in op sometimes these are my normal procedures for ign switches and rarely fail for me
Replacing this can vary from year to year, first thing is to disconnect you battery(first move the seat all the way back cause your going to be under the dash if your seats are power) remove the steering wheel air bag, to do this look for two slots on back side of the wheel towards the ip, these are a spring bar that needs to be pryed to release the bag from the steering wheel, these can make you mental, take your time!! air bags cost a ton!!. then remove the elec. connects that connect the air bag, there is a safety clip that must be lifted up on the connector before you can unplug the connetor, then remove the nut that holds the steering wheel, you will need a steering wheel puller( i leave the nut on by 6-8 threads and firmly but gently rock the wheel back and forth, release and repeat, the nut is left on so you dont eat the wheel when it pops off), ok the bag and the wheel is off, remove the lower hush panel, remove the metal sheild that you see under the hush panel(4--10 mil nuts) then look at your lower strg col cover, some have torx screws to undo some don't. remove the tilt leaver, it pulls straight out remove the lower cover it is snapped to the upper and its a good pull to seperate them, then look up at the upper you will see one more little torx screw holding the upper on to the col assy, remove that screw. now you have the upper loose and the ign cyl. is in the way, look for a little hole on top of the housing...stick a pick in there and turn the ign cyl to the crank pos, once there depress the pin thats down in that hole and pull the cylinder out. right by that hole is a little white tab that has to come out, it has 3 wires going to it the release tab is kinda hard to see so be careful, now go under the dash to the big connector with the 10 gauge wire going to it, undo the 9/32 bolt in the center and pull it out. the 2 outter rows of wires will be staying in the truck its the big center one thats the ign switch harness (some years you will unplug the switch at the switch near the ign cyl, some years you unplug the switch at the big connector under the dash) either way you will see two little slots on each side, stick a pick in there and release each pin while pulling down, be careful the sir coil is near by. so now the switch is out. compare the two, look at the teeth on the old one, set the new one to match, install it and connect all elec connectors for the ign switch, the connect the bat and make sure the new switch is "timed" meaning the acc pos is the acc pos etc, reassembly is the reverse. it sounds hard but its not......so remove air bag, steering wheel, hush panel, metal sheild, lower col cover, undo upper, pick in hole, remove ign cyl. disconnect ign switch harness, remove swtich, time new switch and reass as req....thats all."
Now some bulletins from Chevy (PLEASE NOTE THE INCLUSION OF "2006 and Prior GM Passenger Cars and Light Duty Trucks" which means those not specifically listed...
Models: 2006 and Prior GM Passenger Cars and Light Duty Trucks
2005-2006 HUMMER H2
2006 HUMMER H3
2005-2006 Saab 9-7X
with 4L60-E, 4L65-E, 4L80-E or 4L85-E Automatic Transmission (RPOs M30, M32, M33, MT1, MN8)
This bulletin is being revised to update model years, add additional models and add additional diagnostic information. Please discard Corporate Bulletin Number 01-07-30-002D (Section 07 -- Transmission/Transaxle).
Some customers may comment on one or more of the following conditions:
• The Malfunction Indicator Lamp (MIL) is ON.
• The transmission is defaulted to second gear (4L80/85-E).
• The transmission is defaulted to third gear (4L60/65-E).
• The instrument cluster is inoperative.
Upon investigation, one or all of the diagnostic trouble codes (DTCs) P0740, P0753, P0758, P0785, P0787, P0973, P0976, P1860, P2761, P2764 and P2769 may be set depending on the vehicle.
The most likely cause of this condition may be a loss of voltage to the transmission solenoid power supply circuit.
This condition may also be the result of an incorrect installation of an aftermarket electronic device such as a remote starter or alarm system.
Important: If the vehicle is equipped with an aftermarket electronic device and the DTCs are being set when the device is being used, verify that the appropriate fuse is being supplied battery voltage during operation. If voltage is not present at this fuse, these DTCs will be set due to lack of voltage at the solenoids. This condition is most likely to occur with an incorrectly installed remote starting system. If this is the case, refer the customer to the installer of the system for corrections. ANY REPAIRS DUE TO AFTERMARKET INSTALLATION OF ACCESSORIES IS A NON-WARRANTABLE ITEM.
With the ignition switch in the RUN position, test for battery voltage at the circuit fuse in the transmission solenoid power supply circuit. Refer to the appropriate SI Document for the transmission solenoid power supply circuit information.
If battery voltage is present at the fuse, inspect the ignition voltage circuit between the fuse and the transmission for possible opens.
If battery voltage is not present at the fuse, test for continuity between the fuse and the ignition switch. If NO continuity is between the fuse and the ignition switch, repair the open in that circuit.
If you have continuity between the fuse and the ignition switch, the most likely cause is the ignition switch. Replace the ignition switch using the appropriate Ignition Switch Replacement procedure in SI.
Document ID# 1371241
2002 Chevrolet Avalanche - 2WD
Malfunction Indicator Lamp (MIL) On, Transmission Stuck in Third Gear, Insrument Cluster Inoperative (Replace Ignition Switch) #01-07-30-002C - (Aug 21, 2003)
Malfunction Indicator Lamp (MIL) On, Transmission Stuck in Third Gear, Instrument Cluster Inoperative (Replace Ignition Switch)
1999-2000 Cadillac Escalade
2002-2003 Cadillac Escalade, Escalade EXT
2003 Cadillac ESV
1997-1999 Chevrolet Full-Size Pickup, Suburban, Tahoe (Old Style)
1997-2003 Chevrolet Blazer, Express, S-10
1999-2003 Chevrolet Silverado, Suburban, Tahoe (New Style)
1999-2003 Chevrolet Blazer RH Drive (Export)
2002-2003 Chevrolet Avalanche, TrailBlazer, TrailBlazer EXT
1997-1999 GMC Sierra, Suburban, Yukon (Old Style)
1997-2001 GMC Jimmy
1997-2003 GMC Savana, Sonoma
1999-2003 GMC Sierra, Yukon, Yukon XL (New Style)
2002-2003 GMC Envoy, Envoy XL
1997-2003 Oldsmobile Bravada
2002-2003 Oldsmobile Bravada
with 4L60-E or 4L65-E Automatic Transmission (RPOs M30, M32)
This bulletin is being revised to update the model years and to add additional models. Please discard Corporate Bulletin Number 01-07-30-002B (Section 07 -- Transmission/Transaxle).
Some customers may comment on one or more of the following conditions:
* The Malfunction Indicator Lamp (MIL) is ON.
* The transmission is stuck in third gear.
* The instrument cluster is inoperative.
Upon investigation, one or all of the diagnostic trouble codes (DTCs) P0740, P0753, P0758, P0785, P1860 may be set.
The most likely cause of this condition may be a loss of power to the transmission on circuit 1020. This loss of power may be caused by an open in the ignition switch. This condition may also be the result of an incorrect installation of an aftermarket electronic device such as a remote starter or alarm system.
With the ignition switch in the RUN position, test for battery voltage at the appropriate fuse listed below.
[Edited out chart]
Ignition 0 For the C/K trucks. (2002~2006)
If battery voltage is present at the fuse, inspect circuit 1020 between the fuse and the transmission for possible opens. If battery voltage is not present at the fuse, replace the ignition switch using the Ignition Switch Replacement procedure in the Steering Wheel and Column sub-section of the applicable Service Manual. Refer to group number 2.188 of the parts catalog for part description and usage.
If the vehicle is equipped with an aftermarket electronic device and the DTCs are being set when the device is being used, verify that the appropriate fuse listed above is being supplied battery voltage during operation. If voltage is not present at this fuse, these DTCs will be set due to lack of power at the solenoids. This condition is most likely to occur with an incorrectly installed remote starting system. If this is the case, refer the customer to the installer of the system for corrections.