Non Start / PO740 related issue?

[Ruddbow]

I apologize as I have a tendency to be long winded.

2 weeks ago I attempted to start the truck and it started but immediately shut off. Earlier in the week I recall seeing the "security light" but did not experience any problems. I swapped out the fuel filter and it still would immediately die. I trailered it to a friends and thought I'd double check to see if it would run. Sure enough popped right off and ran fine. I have searched and read all of the threads pertaining to similar issues and I thought I diagnosed it to the ignition switch. Hooked up a scan tool and it pulled a P0740 GMC Torque Converter Clutch Malfunction. I searched on that code and found this:

CODE PO740

The transmission shifts good at all points. I have experienced one odd issue when slowing down to stop. This has happened intermittently over the last few months.

I roll up to a stop sign/light, the truck surges. Best way to describe is if it were a manual tranny and you didn't down shift the vehicle when coming to a stop it would stutter and eventually stall (never depressing the clutch in). My truck just stutters and then it's fine upon acceleration.

Could just replacing the ignition switch take care of both of these problems?

I can find an ignition switch for $90, but from what I read on the security light issues at switch it is a different switch/sensor all together. GM OEM 26075995 Switch, Ignition Starter/Ignition Starter Switch.

I would love any input others have pertaining to these issues. I really enjoy this site and all of the knowledge.

Thank you.

 

[SunlitComet]

Check all the outputs of the switch in different positions to determine if it is faulty at all but if in the unlock or on position the gear indicator should light indicating that the entire tranny should be getting power unless break in a wire down stream of tranny fuse.

Sent from my SPH-L720 using Tapatalk

 

[willxfs]

My rig does this about once every couple of months. Its a 98 2 door with almost 250k on the clock. Turn the key and it fires up beautifully for 1 second. Then just dies immediately. I checked the fuel pressure from the pump and it checked out fine. I also changed the fuel filter. The problem still persists but its so infrequent that I haven't dealt with it yet. I'm thinking the ignition components too. I can always get the truck to start by moving the steering wheel up and down a few times. Keep us posted on what you find. Thanks!

 

[SunlitComet]

My rig does this about once every couple of months. Its a 98 2 door with almost 250k on the clock. Turn the key and it fires up beautifully for 1 second. Then just dies immediately. I checked the fuel pressure from the pump and it checked out fine. I also changed the fuel filter. The problem still persists but its so infrequent that I haven't dealt with it yet. I'm thinking the ignition components too. I can always get the truck to start by moving the steering wheel up and down a few times. Keep us posted on what you find. Thanks!

Just fix it already. If you have to move the steering wheel to start you might end up starting an electrical fire eventually.

 

[Ruddbow]

Frustrating Issues

Still having issues. Even after:
Replaced Brake Switch for stuck on TCC, cleaned valve body, valves.

Mechanic is the best tranny guy in my area. He has worked on it 3 times now and is leaning towards me replacing with a reman. I have been driving it as is because I don't have $2200 to replace. Fuel mileage is bad. Still have the Security Light on but has not left me hanging for several months. I love the truck but these two items are frustrating me like no other.

 

[SunlitComet]

a tranny fix does not fix a security light stuck on.

 

[Ruddbow]

Thank you, I realize 2 separate issues at this point.

 

[SunlitComet]

i think you should resolve the security light problem first.