02 Tahoe security flashing
 

I had to rebuild my transmission on my 2002 Tahoe Flex Fuel 5.3L engine. I disconnected the battery cables before doing my tranny. I later found that i needed to replace leaky fuel lines and ultimately the plastic fuel lines over the gas tank which would not disconnect. I put it all back together to find the engine would not turn over only to find I forgot to plug in the neutral safety switch. The starter turned over fine after that but no fire. I dropped the tank again with the plastic fuel lines disconnected from the metal lines and found they were still dry. I cranked the engine to see if the fuel pump would spit fuel and got nothing. With the fuel relay out, I put a jumper across the gate ports and saw that the new pump and wiring worked fine. I interchanged 4 other identical relays and could not get the pump to spit when I cranked the starter. Then I noticed the Security light flashing on the dash. I know I need an active code reader to reset the security signal. My question is would the disconnected neutral safety switch during the starter cranking cause the anti theft security to engage? I don't want to get a mechanic to reset everything and then not understand what caution to take while I finish buttoning up the rest of my repairs.

I am not quite sure the order of adjustments for the anti theft reset. I called a tech for a price on the reset and he said he would come out for $120. Another tech said he normally closes all the doors and puts the ignition key in the on position for 15 minutes and it successfully resets. 15 nor 20 minutes did not work for me but I still had the error codes registered. I disconnected the negative battery terminal to reset the error codes first, then I will try to reset the anti theft with the key in the on position with doors closed for 30 minutes. If it doesn't work I will have to pay the man to come out with his active OBDI. I just don't like when they say no guarantees and you still owe the fee.

Ok so I am noticing that the security light only flashes when the drivers door is open. With the door open and the key in the ignition not in run position the security light flashes. Once it is in the on position there is no security light flashing.When I crank over the starter there is no security light at all. Do I have a security anti theft problem???

I have no error codes showing with OBDI scan tool. There are no communication errors with the PCM. I realize the ECM sends the neutral ground to the relay for 2 seconds and then the PCM engages continually after that but I am lost as to what to do at this point. Hey where are you guys LOL

I changed the computer hoping to get a favorable result but I still have the problem where terminal 85 and 86 on the fuel pump relay will not show voltage when the key is in the on position. The gate ports when using a jumper wire with the relay out makes the fuel pump work. Where does 85 or 86 receive the 12 volts from????

I made an observation. With the negative battery cable disconnected and the fuel pump relay removed I do get 12 volts at both coil terminals 85 and 86 individually. As soon as I connect the negative battery cable the voltage at 85 and 86 of the fuel pump relay disappears with the key in on position. Even if I toggle from off to on I get nothing. Someone please help me with this. Walk me through.

how are you getting 12v with the battery disconnected? even if its only the neg cable the circuit is still not there and you wont get any power

Let me clarify that. Lol I made that confusing. I should have said I disconnected the negative cable from the battery. Then I put the positive voltage tester cable into relay terminal 85 then 86 with the negative voltage tester cable on the battery lead. There I found 12 volts in both 85 and 86 while the key is in on position. When I connect the negative battery cable to the battery the voltage at terminal 85 and 86 disappears.

I believe you may have this backwards. The PCM sends the 12V to the pump relay terminal 85, terminal 86 is ground. You should see 12V on terminal 85 when you turn the key on or start. Check for continuity on terminal 86 to ground. ( I think have the terminal numbers correct)
I'd be looking for a ground wire that didn't get bolted down (or broken off) when you repaired the tranny.

86 has a positive 12.4 ohms ground with the relay out and the key in the on position. 85 does not ground. The cable to the battery ground was connected for this test.

Not sure why 85 will not get a power source. I know it has to come from the PCM. The internet shows many inputs that are required for the PCM to ignite or maintain relay power. The key word that they don't like to use is maintain or pre-ignition. The PCM sending 2-3 seconds power to the relay previous to cranking the starter is not a part of any of those maintain variables.
Things that maintain which i know don't matter at this point are
Tank pressure sensor
Fuel pressure
RPM input
We know the ground is there. What else does the PCM need to send power to 85? There are no fuses for the fuel pump and the ECM fuse is good.
Can something in the transmission cause an PCM to not send power to a fuel pump relay?

It's possible you have a bad connection at your fuseblock.
The fuel pump relay control is the Dark-Green w/ Wh wire at the PCM (connector 2 pin 9). Check for the 12V there.

I did find on LS1tech.com the wiring diagram of the PCM for a 5.3L engine. Now I see that you are making reference to the 80 Way F Micro-Pack 100 Series connector to the PCM. At first I thought you were making reference to the back of the fuse block. So Pin 9 of C2 is suppose to be a dark green wire with a white stripe. I will look for that. On the back of the fuse block the PCM 1 fuse is the row 11 a pink wire and next to it is a big purple wire. Big because the wire insulator is thicker. Key in the on position No voltage there at all and it is the fuse marked PCM1. On Monday I will trace the wire back from Pin 9 of C2. Hey Bruce I just want you to know I appreciate your input. Chat Monday. I feel like we are getting close.

Look for the wire color (dark green with white stripe), let's hope there is only one.

Print shows fuel pump relay at terminal A7 dark green wire with white stripe on fuse block C2. I'm going to be checking. The main thing I want to check is PCM C1 Pin2 which is 12 volt reference. Not sure if that is the main power for the PCM. Not sure what the 5 volt reference is for at PCM C1 Pin 7. How do they vary from Battery Positive Voltage on PCM C1 Pin 20?
My PCM fuse does not have voltage so I have to find out why. Once it gets voltage then I can check the dark green/white wire on Pin 9 of PCM C2 for fuel pump relay coil power. By the way this is where I get my print.
https://ls1tech.com/forums/conversio...rams-here.html

Problem solved !!!!!
With the key in the on position I had no output voltage on the green/white wire to the fuel pump relay because there was no input voltage powering up the PCM to send output voltage. The under hood fuse panel labels it ECM. It does not receive power from a bus bar in the fuse panel tied to the battery. All of that lost power in its entirety goes through the ignition relay. LOL REALLY. Why can there be no mention of any of this anywhere I have no freaking clue.
So if you can't get fuel pressure with the key in the on position prior to cranking and you can jumper the gate of the fuel pump relay for fuel pressure but nothing with the relay in place, check power on the ECM fuse. If there is no voltage replace the ignition relay. Problem should be solved.