89 K1500 starts then stalls

[jswordy6763]

Originally Posted by MT-2500

Volt meter only checks the voltage to it.

It takes a lab scope to test signal for proper signal.
They can fail or get weak hot or cold and sometimes the plug in does not make good connection.
I had one on a ford one time that would quit and you could unplug it/and or tap on it and it would run another 30-60 days and quit again.
And one on a cavilar that would run 90 days and quit on road.
Let it sit 30 minutes and it woulkd go another 90 days. not 89 or 91 right on 90 days.
Never did figure that one out untill iy finaly quit all together.
Your crank sensor Should be setting a code for it if very bad.

Black stuff in tank can be from a failing fuel pump.
Did you run a full pressure test on it before removing it?

Pressure tests:

1.) Key to ON, pump runs and shuts off. 10 psi. Falls slowly.

2.) R line pinched off at pump, key to ON: 10 psi, falls slowly.

This had been 65 psi prime at ON and holding steady when we tested it 5 months ago, before the truck was allowed to sit idle. If I had the time and parts, I could probably R&R pump and get it going good. I think the little rubber flapper check valve is what is the trouble.

I have instructed owner to get a crank sensor when he gets the pump. This is a Hall effect sensor, I believe (3 wires to it). Found a voltage check I can do on the leads at YouTube. It says one lead 0 volts, one lead 5 volts, one lead 12 volts. No scope, so can't do the waveform.

Your works good/quits stories mirror this truck. When they put in the new pump last time, at first it would start and die. Scary to them, but then a guy started playing around under the hood not knowing WTF he was even doing "and it fixed itself," owner says. Sigh... I asked that guy WTF did you do under there, and he says I DUNNO! Sigh...

The truck had a CHECK ENGINE light for years before this trouble; ran good though. When the truck would not start, owner pulled battery cable to help save battery juice while it sat. You got it! All codes cleared. Sigh... We even scanned it just for grins, nada. It has not run long enough to reset any of them since.

There is a black crumbly stuff in the fuel left in the tank. Not a huge amount, but it is there. Whether that is from this pump or the one that failed before it, who knows? They did not clean tank before.

I think I mentioned this, but we will be pulling fuel filter and draining lines. I hope to catch fuel out of those to inspect for water. Filter was one of the first things we replaced 5 months ago. Maybe it has water in it now.

I ... INTEND ... TO ... WIN on this! Thanks for the help!

[MT-2500]

Originally Posted by jswordy6763

Pressure tests:



This had been 65 psi prime at ON and holding steady when we tested it 5 months ago, before the truck was allowed to sit idle. If I had the time and parts, I could probably R&R pump and get it going good. I think the little rubber flapper check valve is what is the trouble.

I have instructed owner to get a crank sensor when he gets the pump. This is a Hall effect sensor, I believe (3 wires to it). Found a voltage check I can do on the leads at YouTube. It says one lead 0 volts, one lead 5 volts, one lead 12 volts. No scope, so can't do the waveform.

Your works good/quits stories mirror this truck. When they put in the new pump last time, at first it would start and die. Scary to them, but then a guy started playing around under the hood not knowing WTF he was even doing "and it fixed itself," owner says. Sigh... I asked that guy WTF did you do under there, and he says I DUNNO! Sigh...

The truck had a CHECK ENGINE light for years before this trouble; ran good though. When the truck would not start, owner pulled battery cable to help save battery juice while it sat. You got it! All codes cleared. Sigh... We even scanned it just for grins, nada. It has not run long enough to reset any of them since.

There is a black crumbly stuff in the fuel left in the tank. Not a huge amount, but it is there. Whether that is from this pump or the one that failed before it, who knows? They did not clean tank before.

I think I mentioned this, but we will be pulling fuel filter and draining lines. I hope to catch fuel out of those to inspect for water. Filter was one of the first things we replaced 5 months ago. Maybe it has water in it now.

I ... INTEND ... TO ... WIN on this! Thanks for the help!

You are welcome and let us know how it goes.
Good Luck

[jswordy6763]

Pulled the fuel tank last night, cleaned it, installed new fuel pump, rewired harness to an updated fuel pump plug included with new pump, reinstalled tank, removed fuel filter, drained lines, replaced with new filter, and ran out of time.

Located a new crank position sensor. We had trouble locating one yesterday. This weekend, we will plug up the fuel lines and harness, add gas, test pump. Then run through CPS wiring harness and install new CPS if we are back to full prime but no-run condition.

I think once that has all been done, if condition persists, next would be to inspect passlock wiring in the steering column to firewall.

I'll keep you posted on what we find, how it goes. Any other suggestions, they are appreciated.

[MT-2500]

Confirm full fuel pressure on key on prime up and also on engine cranking.
Confirm good hot blue spark to sall plugs engine cranking.
Will engine fire with a shot of carb cleaner.

If security system is shutting it down you still should have a engine run 2 seconds before shut down.
Secuirty system shuts down injector pulse after 2 second engine start/run.
Check the injector pulse cranking engine and for 2 seconds after starting.

Post back what you find.

[MT-2500]

What is the scurity light doing after key on bulb check?
If staying on after key on.
Do the relearn.
If still staying on check the secrity system with a engine /body capable scanner and post back any engine /body /security system codes.

And if you you have done a lot of engine cranking with a no start pull plus and ckeck ends or wet or dry.
If wet and good spark replace them with good AC Delco plus.
If dry you are not getting fuel.
Check fuel delivery.

[jswordy6763]

Well, after this weekend we are extremely disheartened.

1. We do have 60-65 psi fuel pressure now.
2. The new pump does run.
3. The truck just starts and dies.
4. It runs great on carb cleaner. We ran it quite awhile on it.
5. It did not set any engine codes while running.
6. All lights go out on the dash while running (Check Engine, etc.) EXCEPT THE SECURITY LIGHT, which stays on constantly.

We removed the bottom clamshell from the column. The wires running to the tumbler for passlock all seem OK, none were loose.

We have no access to an engine/body capable scanner other than hauling it to a dealer.

We CANNOT do the relearn process as it has been described because the SECURITY light NEVER GOES OUT. It is necessary for it to go out in the relearn process, but you can let the truck sit in ON for 30+ minutes, and still have a solid security light. I know, cuz we did! We also tried disconnecting the battery, which some have said reset their passlock, no luck.

I just don't know what else to do but tell my neighbor to save up to pay the freight to have a dealer fix it now. The problem is clearly in the security system, and without the right level scanner, we are shooting in the dark. Judging by the symptoms, I think it most likely is a bad lock tumbler assembly, but I'm just guessing without a code.

Man, this stinks. Any other ideas?

How do I remove the lock tumbler from the upper column clamshell, so I can remove the clamshell and see up top?

[jswordy6763]

Using Google, I find it looks like the BCM needs to be reprogrammed to accept the relearn process, and then the DTC need to be cleared, and that is a dealer or auto shop process.

[jswordy6763]

Just talked to a mechanic. He says he has dealt with passlock on other vehicles. Says the SECURITY light is on constantly because the lock tumbler (he used a $50 term for it) is bad, not reading the resistance. Tells me to replace it and the ignition switch, try relearn. If it does not relearn after replacement, bring it to his shop and he has a guy who will clear the codes to get it to work.

Sounds right to me, how about you?

[MT-2500]

Originally Posted by jswordy6763

Just talked to a mechanic. He says he has dealt with passlock on other vehicles. Says the SECURITY light is on constantly because the lock tumbler (he used a $50 term for it) is bad, not reading the resistance. Tells me to replace it and the ignition switch, try relearn. If it does not relearn after replacement, bring it to his shop and he has a guy who will clear the codes to get it to work.

Sounds right to me, how about you?

On your passlock R system the ign key tumbler does not read restiance of pellet in key.
That was on older system.

On yours there is a passlock sensor that the ign key turns to send a signal to anti theft/body computer.
Check all wiring and plugins and fuses.
You need a anti theft capable scanner to test it.
Get code and post back code.

If you do no want to go to the dealer look around for a good repair shop that has the righ scanner and know how to deal with it.
Good Luck

[jswordy6763]

Originally Posted by MT-2500

On your passlock R system the ign key tumbler does not read restiance of pellet in key.
That was on older system.

On yours there is a passlock sensor that the ign key turns to send a signal to anti theft/body computer.
Check all wiring and plugins and fuses.
You need a anti theft capable scanner to test it.
Get code and post back code.

If you do no want to go to the dealer look around for a good repair shop that has the righ scanner and know how to deal with it.
Good Luck

Thanks. I have become well-schooled in Passlock versus Passkey, so I understand how each works. They are the same basic concept, except that Passlock places the resistance load in the ignition lock assembly, whereas Passkey places it in the key.

Checking all the fuses was the very first thing we did, way back when. We have checked most all the security wiring. There is one small area to check yet. Barring no open faults, the symptom seems adequately isolated to the ignition switch/ignition lock areas.

"Get code and post back code" doesn't work real well around here unless you have a friend who works at a shop with the correct scanners and experience, which we don't. Usually "get code" around here means the shop will get the code for itself to fix the entire problem for you. They are not in the habit of just scanning stuff and letting repairs be done elsewhere.

I am probably going to attempt to get a resistance out of the system, like this:

http://www.automotiveforums.com/t698...problems_.html

http://www.grandamgt.com/forum/showthread.php?t=74971

If I can, then I can bypass it with like resistors. The mechanic says the solid SECURITY light which never goes out is caused by the system not reading anything from the ignition lock assembly at all. The SECURITY light illuminates just the same as if the yellow wire had been cut.

When it does eventually run, I will post what was found and how it was fixed.

[jswordy6763]

Last night, I performed the operations necessary to do a resistor bypass of the ignition switch lock assembly, using the orange/black and yellow security wires. I did this because if I could get a reading, I would bypass. If not, it would narrow the diagnostics.

I got no resistance reading out of the lock assembly over a few tries, pretty much confirming that the problem is likely isolated to the ignition lock assembly, as suspected. Since during this test the yellow wire is cut, and the ohm meter is essentially reading only the passlock sensor's resistance at that point, it seems logical the lock assembly passlock has a fault. That would also cause constant SECURITY light on the dash, just as cutting the yellow wire and installing a switch to bypass the system in fail/safe does.

It may also involve the ignition switch, and so while we are there we will likely replace that, as well. GM techs tell me the switch can burn/carbon at the same time as the passlock circuit opens, and for $88 aftermarket, it seems a reasonable matter to also replace it rather than have to tear into things again later.

I am preparing to order the lock assembly today, and track down some socket-style Torx bits. Your thoughts?