If you are sure the battery is good and fully charged and the cable connections are all good. You will need to check for voltage at the small purple wire on the starter solenoid while some one engages the starter. If you have good voltage at the purple wire and at the large battery terminal both, you will need to replace the starter. If you do not have voltage at the purple wire let me know so we can test the starting system and find where the problem is. I will need to know if it is a standard shift or an automatic. But be sure to check to see if you have any theft or security lights coming on, on the dash first. It may be an issue with the security system also. Thanks, Bob
OK, that's what we needed to know. That means that there is an open circuit between the ignition switch and that wire where it connects to the starter. Under the hood, there is a fuse box mounted on the fender. In it is a starter relay, that may or may not be the problem. If you look around there may be another relay that is the same configuration, if so, swap them and see if that helps. And you can jumper terminal 87 to 30 with the relay out and see if that makes it crank. If so, the relay is bad. Terminal 65 is a ground. The wire colors on we care about are 87=purple, 85=black, 50= red. If that does not help, check the crank fuse in the instrument panel fuse box. Fuse number 8, it is a 10 amp and will also stop the starter circuit from working. Next is the nuetral safety switch, which is also known as the back up lamp or range switch. Located on the side of the transmission, the shift linkage going into the transmission is where it is at. Slips over the stub going into the trans case. Check it in park and in nuetral both, to see if the starter will crank, try wiggling the gear shift in nuetral and park. Purple wire, (may have a white stripe) for power from ignition when key on crank, purple going out to solenoid. If both purple are hot when turning key to crank, switch is ok. If no power to either, go to ignition switch to test. Remove the cover under the dash at steering column and check the big red wire for power into the ignition switch from the battery, when you turn the key to crank, should get power to the yellow wire that goes to the relay and solenoid. If all of this checks ok, then you have a broken wire in the system and we will need an ohm meter to check them all for continuity. You may also want to check for any other bad fuses in all of the fuse boxes as sometimes a fuse for another circuit that you would never suspect, will cause a back feed and make a problem for a circuit it should not even be related to. Let me know what you find and we will go from there. Also sending a copy of the wiring diagram for the starter circuit. Also a flow chart, note the blue high lights will not open for you. GM access only. Thanks
Is the voltage reading the same as the battery voltage?
Go to Step 13
Go to Step 2
Does the test lamp light?
Go to Step 3
Go to Step 14
Connect a jumper wire between cavity 30 and 87 of the starter relay socket.
Does the starter solenoid click?
Go to Step 4
Go to Step 15
Go to Step 5
Go to Step 16
Go to Step 17
Go to Step 6
Is the vehicle equipped with a manual transmission?
Go to Step 7
Go to Step 9
Go to Step 8
Go to Step 11
Does the engine crank?
Go to Step 18
Go to Step 19
Go to Step 10
Go to Step 20
Go to Step 21
Go to Step 22
Go to Step 12
Measure the voltage between the connector C266 cavity D5 and ground.
Go to Step 23
Go to Step 24
If the starter motor does not pass the test, replace the starter motor.
Is the repair or replacement complete?
Go to Starting System Check
Install the starter relay and repair the open in CKT 244 (RED) between fuse 6 and the starter relay. Refer to Wiring Repairs in Wiring Systems.
Is the repair complete?
Install the starter relay and repair the open in CKT 6 (PPL) between the starter relay and the starter solenoid. Refer to Wiring Repairs in Wiring Systems.
Install the starter relay and repair the open in CKT 150 (BLK) between the starter relay and ground G105. Refer to Wiring Repairs in Wiring Systems.
Replace the starter relay.
Is the replacement complete?
Repair the open in CKT 1035 (PPL) between the clutch pedal position switch and the starter relay. Refer to Wiring Repairs in Wiring Systems.
Replace the transmission range switch. Refer to Park/Neutral Position Switch Replacement (4L60-E) or Park/Neutral Position Switch Replacement (4L80-E)in Transmission/Transaxle.
Repair the open in CKT 5 (YEL) between the transmission range switch and the starter relay. Refer to Wiring Repairs in Wiring Systems.
Replace the ignition switch. Refer to Ignition Lock Cylinder Replacement - On Vehicle (Standard Column) or Ignition Lock Cylinder Replacement - On Vehicle (Tilt Column)in Steering Systems.
Repair the open in CKT 242 (RED) between the ignition switch and the underhood fuse block. Refer to Wiring Repairs in Wiring Systems.
I am going to send you the procedure for reprograming the pass lock system on the truck, just on the off chance that it is cause the problem. Then in another post, I will send you the flow chart on the starter system. If it is not the pass lock, it has to be an open circuit between the ignition switch and the starter solenoid, which is why I send you so many instructions on seeing where there is power and where there is not. Example, if you have power into the nuetral safety switch and none out, then it is the switch. Try the reprogram and let me know. OOps, see I already sent you the flow chart. Let me know where it had power and where it did not, so I know where your at.