[HardDog]

What I have is a plain key that inserts in to a lock tumbler that has a magnetic strip that provides the low resistance signal to to the ecm. Whatever we call it it is the oem anti-theft system.

 

[oldeerslayer]

If your truck is at a performance shop they should be able to figure it out. That's what you are paying them for.
On TV I never see the Martin brothers or Dave Kindig calling up their customers asking for help to figure something out.
Maybe at Cousin Ricky's auto body, engine swap, and Tacoria they do it that way.

 

[GSettle]

Are you sure it’s an LS? I thought Silverado’s didn’t get them till ‘99??

 

[oldeerslayer]

Post #6 he corrects it. It's an L31 Vortec 5.7L.

 

[BadReligion]

We have checked all the harness grounds, and fuses im assuming? It's been a long time since I've worked on gen 1 stuff, didn't the ecm look for oil pressure on cranking?

 

[oldeerslayer]

There is a redundant oil pressure circuit to the fuel pump relay. If the ECM is receiving a pulse from the distributor it turns on the fuel pump by activating the relay. Or if you have oil pressure, that will activate the pump directly. Not all swappers use this type oil pressure switch. Later year 4.3 Vortec's didn't have that circuit either, but a 96-97 would have had it. It's not necessarily needed. If you aren't getting an ignition pulse no need for fuel. Prior to computers GM used it as a safety feature. If you didn't have oil pressure, you didn't need fuel. Like if the truck is upside down.
It sounds to me like something from the ignition switch to the ECM is wired incorrectly. Sounds like you have 12V in run, but not in start. Check fuse #10 ECM/IGN to be sure it has power in both run and start. I've run across custom harnesses that failed to provide power in both positions. Usually when someone is building a harness they check for continuity in run, but don't always check it in start. Basically all pink wires are hot in run, but not all are hot in start. This is done to prevent surges from damaging sensitive electrical components.
Or it could be a problem with the ignition switch.

 

[jslezak83]

[QUOTE="oldeerslayer, post: 12345334, member: Usually when someone is building a harness they check for continuity in run, but don't always check it in start. Basically all pink wires are hot in run, but not all are hot in start. This is done to prevent surges from damaging sensitive electrical components.
Or it could be a problem with the ignition switch.
[/QUOTE]

I think pink wires with black trace are typically for keyed 12V that is hot in start position.

 

[HardDog]

There is a redundant oil pressure circuit to the fuel pump relay. If the ECM is receiving a pulse from the distributor it turns on the fuel pump by activating the relay. Or if you have oil pressure, that will activate the pump directly. Not all swappers use this type oil pressure switch. Later year 4.3 Vortec's didn't have that circuit either, but a 96-97 would have had it. It's not necessarily needed. If you aren't getting an ignition pulse no need for fuel. Prior to computers GM used it as a safety feature. If you didn't have oil pressure, you didn't need fuel. Like if the truck is upside down.
It sounds to me like something from the ignition switch to the ECM is wired incorrectly. Sounds like you have 12V in run, but not in start. Check fuse #10 ECM/IGN to be sure it has power in both run and start. I've run across custom harnesses that failed to provide power in both positions. Usually when someone is building a harness they check for continuity in run, but don't always check it in start. Basically all pink wires are hot in run, but not all are hot in start. This is done to prevent surges from damaging sensitive electrical components.
Or it could be a problem with the ignition switch.

Thank you I will check that.

 

[HardDog]

We have checked all the harness grounds, and fuses im assuming? It's been a long time since I've worked on gen 1 stuff, didn't the ecm look for oil pressure on cranking?

I have fuses and grounds. I do have another I have to track down. The O2 sensor is getting warm when switch is on or is that normal thinking possible short

 

[BadReligion]

I know I may sound like a jerk. Did you continuity test the fuses? Many times they will look fine and actually be "tripped"

 

[ScottyV1966]

Wow! I'll just Keep my 2.2, My Brain would hurt less! I scored a free 4.3 V6 from a 97 blazer today. Think I will pay it forward. It would be too much confusion getting it to work on my 1995.

 

[oldeerslayer]

Putting a 97 Vortec style 4.3 into a 95 would be a giant nightmare even if the truck was originally a 4.3. 96 up engines, wiring, and computers are completely different from 95 and earlier. There are also exhaust, cooling system, and other differences. I've been working on S10's since they came out, both on my own and professionally and I wouldn't attempt it.
You'd spend the next 2 years chasing parts.