It may be a bad connection at battery terminal scrape and clean.
I wouldn't suspect ignition switch , not without testing . B+ voltage in an out . I would do voltage drop testing on the main battery supply cable to the starter an under hood fuse box . You could have bad connection or bad cable , Starter Voltage Drop
When turning the ignition key to start ,voltage is sent to the PCM - engine computer . When the PCM see's this voltage it energizes the starter relay , closing the contacts inside the relay sending B+ voltage to the S terminal on the starter solenoid . Before replacing parts use a volt meter an test for B+ voltage at different places in the underhood fuse / relay box . IGN A 40 amp fuse . This fuse supply's B+ to the ignition switch . If you have B+ there , test at the CRANK fuse 10 amp while someone turns the key to start . IF B+ voltage is read there ignition switch is OK . Crank fuse is also located in the underhood fuse box.
On vehicles that have several control modules connected by serial data circuits, one module is the power mode master (PMM). On this vehicle the PMM is the body control module (BCM). The BCM uses 3 signals from the ignition switch. These are the Ignition 0, Ignition 1, and Accessory.
To determine the correct power mode the BCM uses:
• The state of these signals
• The sequence of switch closures received by the BCM
• The status of the engine run flag
The chart indicates the power modes detected and transmitted by the BCM:
Fail-safe Operation
Since the operation of the vehicle systems depends on the power mode, there is a fail-safe plan in place should the body control module (BCM) fail to send a power mode message. The fail-safe plan covers modules with discrete ignition signal inputs as well as those modules using exclusively serial data control of power mode.
Serial Data Messages
The modules that depend exclusively on serial data messages for power modes stay in the state dictated by the last valid BCM message until they receive the engine status from the powertrain control module (PCM). If the BCM fails, the modules monitor the serial data circuit for the engine run flag serial data. If the engine run flag serial data is true, indicating that the engine is running, the modules fail-safe to Run. In this state the modules and their subsystems can support all operator requirements. If the engine run flag serial data is false, indicating that the engine is not running, the modules fail-safe to OFF-AWAKE. In this state the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.
Discrete Ignition Signals
Those modules that have discrete ignition signal inputs also remain in the state dictated by the last valid BCM message received on the serial data circuits. They then check the state of their discrete ignition input to determine the current valid state. If the discrete ignition input is active, B+, the modules will fail-safe to the RUN power mode. If the discrete ignition input is not active, open or 0 voltage, the modules will fail-safe to OFF-AWAKE. In this state the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.
×
Go to www.reliable-store.com
they've got solution to all technical problems
IF battery voltage is above 12.2 volts, I'd suspect a bad IGN switch
SOURCE: My GMC Envoy 2005 has
Hey. Your problem look to be a battery concert.
if you are sure of the battery is Ok.
Remove the Battery terminal inspect and clean.
And put back the teminals. Tight a little hard.
because one of the problems on this kind if vehicles are the battery conncetions. That came in misscontact.
After all of this . Check all the fuses Include the MEGA FUSES.
Replace as need. with the same rating.
Check the Red wire going to the fuse block. If is nessesary
Go to the autopart and buy a test light.
OK.... I hope this can be a start prosses to fix your car.
SOURCE: the ignition won't turn for a 2003 gmc yukon denali
make sure the wheels are straight.. if you park them with them turned to one side the steering column is under a bind.... if they are turned all the way to the right you will for example have to turn it a little to the left to release pressure as you turn the key...
SOURCE: 2005 GMC Sierra 2500HD 6.0 Won't turn over
I have seen many ign switchs. Check to see if the theft doesn't flash when you try to start. It is still posable that the starter is going. Have someone crank the engine. Check for power on the purple wire. If there is power and the it does not crank. Check that the big wire has a soild 12 volts. You can use a screw driver and jump the purple and the big 12v battery at the starter and it should turn on if not replace the starter
145 views
Usually answered in minutes!
×