Newbie with a 2005 Trailblazer 4.2 that died, will not start

[boes462]

First off thank you to anyone that can give me any advice. It is much appreciated.

My wife was dropping my child off at school this morning when her Trailblazer died in the middle of the street.
With the help of a crossing guard they pushed it out of the way.
I was not able to get it started and had it towed to our home.

First thing I did was run a fuel pressure check...none.

I followed a test procedure that i found on you tube that involved removing the fuel pump relay and probing the socket.
standing over the driver side fender, facing the fuse block i get the following:

Lower right hole has battery voltage.
Lower left hole has good ground.
Jumping lower right to upper left gets me around 42 psi of fuel pressure. (seeming to rule out the fuel pump?)
Here's the kickier. Upper right has nothing. No voltage key on or off.

Any ideas?

Thank you very much for any help.

 

[6716]

First off thank you to anyone that can give me any advice. It is much appreciated.

My wife was dropping my child off at school this morning when her Trailblazer died in the middle of the street.
With the help of a crossing guard they pushed it out of the way.
I was not able to get it started and had it towed to our home.

First thing I did was run a fuel pressure check...none.

I followed a test procedure that i found on you tube that involved removing the fuel pump relay and probing the socket.
standing over the driver side fender, facing the fuse block i get the following:

Lower right hole has battery voltage.
Lower left hole has good ground.
Jumping lower right to upper left gets me around 42 psi of fuel pressure. (seeming to rule out the fuel pump?)
Here's the kickier. Upper right has nothing. No voltage key on or off.

Any ideas?

Thank you very much for any help.

There are some manuals you can download here on this site. They include a lot of electrical schematics. Even if you don't find your answer on this particular problem, they will be helpful as you continue with your TB.

I'd start there ... since I don't actually know how to help you otherwise. Somebody smart will check in soon enough, though, and see your post.

 

[The_Roadie]

Welcome! Sorry to hear what brought you here.

That's an OK process, but doesn't take into account what usually fails on our vehicle, and it's the ignition switch. You can troubleshoot it using the schematics, or just spend $30 and swap it because it will fail sooner or later anyway.

http://gmtnation.com/f93/how-replace-your-ignition-switch-3430/

Also check all the fuses with a meter for continuity. A visual inspection isn't always enough. Assume you have a meter?

 

[boes462]

Welcome! Sorry to hear what brought you here.

That's an OK process, but doesn't take into account what usually fails on our vehicle, and it's the ignition switch. You can troubleshoot it using the schematics, or just spend $30 and swap it because it will fail sooner or later anyway.

http://gmtnation.com/f93/how-replace-your-ignition-switch-3430/

Also check all the fuses with a meter for continuity. A visual inspection isn't always enough. Assume you have a meter?

Thanks for your advice Roadie. As i browse threads i'm finding that you are full of knowledge!

I do have a meter and test light.

I hadn't considered the ignition switch because i really don't have any of the other symptoms that are generally associated with it.
however if that is the first place i should look, i'll do just that.


Something i forgot to add last night: ENGINE HAS NEVER FAILED TO CRANK. Just doesn't start. also, fuel pressure when using a jumper at the relay was nearly 60 lbs. not 42 like i originally stated.

 

[ElAviator72]

Most likely not the ignition switch.

Check your fuel pump relay wiring.

The stealership just fixed our truck, that was having the same symptoms as yours.

The determination was that the relay wires going into the fuse box were wonky. I could get the truck to run for a while by changing the fuel pump relay or swapping it with an identical relay (like the washer or hi beam relay). Total repair bill: $165.

 

[boes462]

he

Most likely not the ignition switch.

Check your fuel pump relay wiring.

The stealership just fixed our truck, that was having the same symptoms as yours.

The determination was that the relay wires going into the fuse box were wonky. I could get the truck to run for a while by changing the fuel pump relay or swapping it with an identical relay (like the washer or hi beam relay). Total repair bill: $165.

Was not the ignition switch.

Doing the exact same thing.

I have checked all fuses (with a meter) and they all are good.

At one point during testing the fuel pressure shot up to sixty. The pressure gauge bounced around for a moment and i heard a clicking noise near the pcm. Then it simply dropped and has never done it again.
ibefore it quit i stuck my hand on all the relays, none of them seemed to be the source of the clicking.

 

[boes462]

Thanx for all the info, but I gave up.
After running all of the test that I felt comfortable with, I had it towed to the local Chevy dealer.

It's been there a couple hours and they have called me with an estimate to replace the ignition switch.

I JUST REPLACED IT THIS MORNING!!!

AFTER TELLING HER THIS, SHE SAID THAT THEY WOULD CHECK A FEW MORE THINGS.

Should I be concerned?

Keep in mind, I told them everything that I had done including the ignition switch swap.

 

[MAY03LT]

AFTER TELLING HER THIS, SHE SAID THAT THEY WOULD CHECK A FEW MORE THINGS.

So they were going to guess an ignition switch? It's like you went to trailvoy in real life.

Should I be concerned?

It depends on what they have done to lead them to believe that the ignition switch was the cause. What you saw in the video and what we talked about was straight from the service manual for a no fuel pressure diagnosis. We (you) did everything except use the fancy scan tool to force the pcm fuel pump control circuit on. Since the pcm controls that circuit, there's no DIY testing for it, it has to be done with a hi-end scan tool. The result of that test is critical for determining what to test next.

I say ask questions. Since most service advisers are cartards you might have to talk the technician directly to get an idea of what he's done and doing. For all we know, your truck went to a punch and hammer technician who has no powertrain diagnostic experience whatsoever. I hope this isn't the case. Good luck and keep us posted!

 

[boes462]

Revived second call from dealership.
They are now saying it is the PCM.
They are telling me it falls under an 8 year/80,000 mile powertrain warranty that I didn't know it even had.

They're telling me it will be done in the morning.

Crossing my fingers!

I want to thank you all for your help!

 

[MAY03LT]

They are now saying it is the PCM. They are telling me it falls under an 8 year/80,000 mile powertrain warranty that I didn't know it even had.

BOSS! If possible, find out if the fuel pump control driver failed. Might help someone down the road. Thanks for the update!!!

 

[The_Roadie]

Sorry about my first guess, but it was a lot cheaper and statistically more likely than the PCM.

The extended warranty for emission-related items is a US federal requirement. Mentioned also in the Owner's/Warranty manual that should have come with the vehicle, or you can easily Google for it. Every owner should make themselves familiar with what it does and doesn't cover.

 

[boes462]

The results:

"Performed diag. Found p1682. Found internal open in pcm. Replaced pcm, but could not program due to low voltage on circuit 439.
Performed diag. Found broken wire pcm to connector c100. Replaced wire and terminals. Programmed pcm. Checked ok after repair.
Used part#'s:
19210065 refurbished module, 3 Packard terminals."


I don't know that any of this will ever help anyone, but I thought I'd share.

Thanks again to all who offered advice.

**Roadie** The ignition switch was an inevitable repair anyway. Better to replace it now than leave the wife and kids stranded later.

Thanks again.

- - - Updated - - -

The results:

"Performed diag. Found p1682. Found internal open in pcm. Replaced pcm, but could not program due to low voltage on circuit 439.
Performed diag. Found broken wire pcm to connector c100. Replaced wire and terminals. Programmed pcm. Checked ok after repair.
Used part#'s:
19210065 refurbished module, 3 Packard terminals."


I don't know that any of this will ever help anyone, but I thought I'd share.

Thanks again to all who offered advice.

**Roadie** The ignition switch was an inevitable repair anyway. Better to replace it now than leave the wife and kids stranded later.

Thanks again.

 

[The_Roadie]

No charge to you?

 

[MAY03LT]

The results:

"Performed diag. Found p1682. Found internal open in pcm. Replaced pcm, but could not program due to low voltage on circuit 439.
Performed diag. Found broken wire pcm to connector c100. Replaced wire and terminals. Programmed pcm. Checked ok after repair.
Used part#'s:
19210065 refurbished module, 3 Packard terminals."


I don't know that any of this will ever help anyone, but I thought I'd share.

Thanks much for following up!

P1682 sets when the pcm detects a difference between the TAC supply voltage and pcm supply voltage. Me thinks someone banged in a pcm without confirming (a lack of) voltage at the pcm C1 pin 19 first. Either way, glad its fixed and if anything I learned something from your experience so cheeaaahhhhhh!!

 

[boes462]

No charge to you?

No charge at all!

This went so much smoother than I expected .

Glad it happened when it did. Come February we''ll be out of the 8 year warranty.

 

[Sillycracker]

Is there some sort of safety to prevent restart in the event of an accident? I got pulled off after getting belly hung, I have alot of snow experience, but this is my fiancee's truck and I am frankly embarrassed. Can anyone help me?

 

[christo829]

Is there some sort of safety to prevent restart in the event of an accident? I got pulled off after getting belly hung, I have alot of snow experience, but this is my fiancee's truck and I am frankly embarrassed. Can anyone help me?

Do you get any crank at all? Do you hear the fuel pump whine for a couple of seconds when you first turn the key to the run position? Have you checked all the wiring
underneath? There's at least one ground that might have gotten hit if snow/ice got shoved up while the truck was being pulled off the snowbank.

Good Luck!

Chris