TRailblazer start issues

[Waynold78]

As I’ve read so many of these threads , I have a good one for you guys and gals...
2004 trailblazer, battery was out of vehicle for 30min, was trying to upgrade my battery to a group31, however put my oem battery back in, and now truck won’t start, I have spark, no dash lights, fuel relay works, no pump noises , fuel filter is good,
I read somewhere that if you have pulled battery that it needs to relearn, my throttle body is clean,
Is there an easy way to see if my fuel pump is a goner other then dropping the tank?(it’s full)

 

[mrrsm]

Welcome to GMT Nation...

Start by visiting this next Link and Downloading a GM OEM Complete Digital Shop Service Manual ( Courtesy @Mooseman) for your particular Vehicle which include the Factory Diagnostic Procedures and Repair Flow Charts you will need:

Need service manuals? Get them here!

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gmtnation.com

Besides the possibility of having a Bad Ignition Switch as being #1 on the Problem Runway... Watch the Video to observe how the VOP (Video Original Poster) inspects and checks for the "Special Grounds" for the G-201 AND the Splice Pack Ground Comb for the Class 2 Network at SP-201 at the very same location:

For Diagnosing the "Cranks ... No Start" or "No Start-No Crank" Issues. Use the Attached Schematics to follow along with @MAY03LT:

Download, Save and Watch these Videos COMPLETELY or you will MISS CRITICAL INFORMATION.

When you write about what you did... Include each and every one of the steps that you took prior to the situation you have developing with as much detail as possible , as it will help to eliminate certain things and focus on what needs attention.

If your Problem Descriptions are Vague... You can expect to receive Vague Answers. For example... Put a Scan Tool on the SUV ASAP, Document each and every Code stored inside of the PCM in their exact order of appearance. Do NOT Clear ANY Codes... and then Post that information back here.

 

[gmcman]

Welcome!

Just curious why you would want to use a Group 31 battery? I assume for an aftermarket stereo?

Are you specifically after top posts or more reserve capacity? Only reason I say that is you can get good AGM dual post Group 78 batts like the X2.

Before you removed your old battery....was the key off? Not sure if that would matter but I try to make sure the doors are closed and the key is off, reducing load on battery and remove the NEG first.

Did you accidentally connect the cables backwards while trying to connect the group 31 or momentarily short a lead during the process? Did you try to jump start it?

I would check all your fuses, mainly your big 125A #48 located closest to the front.

Edit: @MRRSM and I were typing at the same time.

 

[christo829]

You said your fuel pump relay was working, but no pump noises. Does that include the priming cycle that runs for a few seconds when you turn the key to "Run"? If you can't hear anything, or don't have someone else that can listen back by the tank when you turn the key, do you have a fuel pressure gauge? If so, you can at least check to see if the pump primes.

Good Luck!

Chris

 

[Maverick6587]

Did you accidentally connect the cables backwards while trying to connect the group 31 or momentarily short a lead during the process? Did you try to jump start it?

I would check all your fuses, mainly your big 125A #48 located closest to the front.

Edit: @MRRSM and I were typing at the same time.

I agree with gmcman here. If your vehicle worked before you pulled the battery and now you have no dash lights. I would assume that you blew a fuse/relay. I would do a continuity test first (fastest way to test all of the fuses), as all of the fuses will not have power even with the key in the ON position.

Relays are expensive so, if one is bad, make sure that you know which one. You can pull relay number 43, bright headlamp relay (make sure your brights work first of course) and swap it out with the other 3412 relays in the fuse box to see if any of the other 3412 relays are bad. You can also buy a relay tester if you'd like.

 

[budwich]

As I’ve read so many of these threads , I have a good one for you guys and gals...
2004 trailblazer, battery was out of vehicle for 30min, was trying to upgrade my battery to a group31, however put my oem battery back in, and now truck won’t start, I have spark, no dash lights, fuel relay works, no pump noises , fuel filter is good,
I read somewhere that if you have pulled battery that it needs to relearn, my throttle body is clean,
Is there an easy way to see if my fuel pump is a goner other then dropping the tank?(it’s full)

Ya... it needs to relearn how to start... what do you mean "no dash lights"?

 

[Waynold78]

The group 31 is for a very large stereo yes, keys were off and negative always first one on and last one on, I didn’t even hook up the battery as the stock tray will not come close to accommodating g the battery so I will have to get creative . The maxi fuse is good(125a), I have probed every fuse for continuity ,

Mrrsm, thank you for the download links, that will be super helpful!!! I downloaded a few now, and will try a few here shortly!

The videos posted , I tried the last one, however scan tool pulls up nothing , it runs when fuel is added to intake manuallly but there is no pump whatsoever , I will check the ground first as that is the easier by the hvac actuators ,

Thank you guys for the quick response e

 

[Maverick6587]

You don't hear the pump prime when you turn the key on?

 

[Waynold78]

No check engine or engine with arrow down,

Also swapped relays as this is a very common thing, I swapped with my ac relay(same number) and nothing, I don’t get a fuel pump hum, and my truck drove fine , I drove it to where it is parked with no hesitation. Which is what leave me stunped

 

[Waynold78]

You said your fuel pump relay was working, but no pump noises. Does that include the priming cycle that runs for a few seconds when you turn the key to "Run"? If you can't hear anything, or don't have someone else that can listen back by the tank when you turn the key, do you have a fuel pressure gauge? If so, you can at least check to see if the pump primes.

Good Luck!

Chris

This is a big no, no hum, no 3seconds, I even took the fuel filter out and tried priming without it and not a drop

 

[Maverick6587]

I had a similar issue with my fuel pump. I unplugged the battery to replace a part and then it wouldn't start. It ended up being a few bad grounds to start and then the fuel pump ended up being dead as well.

From that wiring diagram screenshot... Check continuity on ground G305. There are two grounds on the outside of the driver's side of the frame. I would clean them both and apply dielectric grease to them.

The brown wire is the 5v low ref voltage wire, check that. It is the brown wire on the PCM, pin 29. It doesn't list which PCM connector it is though. You could slightly drop the tank and check it on the fuel pump connector itself.

The pink (purple) wire is the fuel level.

 

[Waynold78]

I cleaned said ground last night, ^ just tried to bypass the pcm and hook up a fused wire to the pump directly and a ground, both wires are fine, however the pump(grey) doesn’t read voltage when key on

 

[Waynold78]

I cleaned said ground last night, ^ just tried to bypass the pcm and hook up a fused wire to the pump directly and a ground, both wires are fine, however the pump(grey) doesn’t read voltage when key on

Scratch that, does have power and ground is good for sure! I’m an idiot and had multimeter to wrong spots! I’ve come to the conclusion fuel pump is done! Thanks everyone I will keep postee

 

[budwich]

interesting coincidence... working on battery kills fuel pump. did you measure the resistance across the wires that you just hookup to use the "direct connection"... this will tell you if the wiring to the pump and thru the pump is good.

 

[Waynold78]

interesting coincidence... working on battery kills fuel pump. did you measure the resistance across the wires that you just hookup to use the "direct connection"... this will tell you if the wiring to the pump and thru the pump is good.

No, this I did not do...
I just tried to power the puMp with a fused wire and ground direct from battery and nothing, (with unplugged from vehicle), ordered a new pump$51 shipped!

 

[budwich]

ok... no problem... it was just a thought. Of course, "thoughts" are contagious... can you explain how you hooked up your power / battery AND the ground to the pump?... especially since the ground doesn't come back to the fuse box ( ie. you have to go digging near / at the pump itself or otherwise)

 

[Maverick6587]

No, this I did not do...
I just tried to power the puMp with a fused wire and ground direct from battery and nothing, (with unplugged from vehicle), ordered a new pump$51 shipped!

You bought just the pump motor and not the fuel pump assembly? Is it an ACDelco motor? Interested, as I would like to rebuild my old fuel pump as a spare.

 

[Mooseman]

$51 for a complete fuel pump assembly likely means it's an eBay CCC (Cheap Chinese Crap) or a really good deal on a name brand. ACDelco or Bosch (ACDelco supplier) are our go to. Delphi is a close second. Heck, I would recommend ANY name brand before any CCC junk.

 

[Waynold78]

It’s an ac Delco, is from a friend who used some discounts and pulled some strings for me. Says it’s new open box, heck even if it’s white box at this point if it gets me through I’m happy! It’s a whole setup drop in, I will be playing with the old one when new one is in and working as I am in the rc hobby and it looks to be a standard 540 brushes can in there!! I will keep you all posted, I appreciate each and every response as it is helpful!

 

[Waynold78]

ok... no problem... it was just a thought. Of course, "thoughts" are contagious... can you explain how you hooked up your power / battery AND the ground to the pump?... especially since the ground doesn't come back to the fuse box ( ie. you have to go digging near / at the pump itself or otherwise)

I ran a wire from my battery and the ground to the pump harness(with pins) I appreciate your thoughts, made me think twice! I tried this with the tank on the ground if that makes more sense

 

[Waynold78]

So pump went in without a hitch, few priming cycles and bam up she goes, no leaks, thank you all for your help! I downloaded all the manuals which helped