Let me start from the beginning so someone might understand. I woke up yesterday morning and started my truck. (1998 gmc sierra c1500 2wd 305 “5.0”). It ran amazing. I shut it off because I had forgotten something in the house. I grabbed what I needed and proceeded to put it in my truck. I hit the key and the starter made a noise like the motor was locked up. UI just put the fresh motor in it 500 miles ago) so I knew it couldn’t be. I proceeded to check the ground and nothing happened when I hit the key. I got the voltmeter out of my shop and put it on it. 12.17 volts. Battery was good. Unhooked the ground pulled the starter off and went to a local parts store and got the starter tested. Good starter. Put the starter back on and the ground and hit the key didn’t even click. Got under the truck jiggled the wires to make sure they were tight and hit the key. This time I realized that the dash (cluster and radio) wasn’t working. I then proceeded to hear the fuel pump not running. I instantly knew it had something to do with the ignition module. I look in my fuse box under my hood ignition fuse B was popped. Put a new one in it hit the key and it fired straight up.. and then cut off. I’ve been doing research and everyone says to reset the security system if the security light is flashing. But mine is solid? The whole truck is completely restored so it’s practically brand new. It has spark fuel and air ground and hot. I don’t know what’s wrong. Please send help.

 

1) A battery reading 12.17 volts doesn’t mean it’s good. To properly check a battery it needs to be load tested using a machine or the vehicle electrical system.

That said, these trucks tend to have more problems due to the batteries connections not being properly tightened. It’s very easy to strip the bolts and not realize it, so the easiest test is to grip the cable just below the bolt and try rocking it back and forth. If it moves at all, it’s not tight. The stock bolts can be replaced with a 3/8x16 hex bolt that’s 1” or 1.25” long - thread a nut onto the bolt, tighten the bolt into the battery, then snug the nut against the cable. This is a reliable way to keep the terminals tight.

2) If the security (Passlock) system is activated, it will allow the engine to start for 2 seconds and then the PCM shuts off the fuel injectors. The security indicator can be flashing OR on steady.

A security issue can be confirmed by checking for codes - I believe it’s a P1630 or P1626 that sets.

Follow the instructions below to perform the relearn procedure - make sure the battery is fully charged or that there’s a charger on it and all other accessories are off - it takes 30 minutes to complete.