04 Trailblazer no crank no start

Trchamp

Original poster
Member
Dec 23, 2012
20
Drove truck home and it was fine. Went out Monday and it would not start or turn over. Replaced the ignition switch and neutral safety switch. The crank fuse has correct volt when you turn key. When you ground starter relay motor turns over. Thing that don't work. Back up lights, gas gauge reads on e also added gas. Check engine light does not come on when you turn key. All worked when i drove it home. Help. Also if i buy a used pcm will it start if that is the problem. I know i need to take it to dealer to program. But will i be able to drive it there with used pcm. Thanks Trchamp
 

gmcman

Member
Dec 12, 2011
4,656
Does it make a "click" when you turn the key?

Did you check the battery connections?

Welcome to the club.
 

christo829

Member
Dec 7, 2011
499
Fairfax, Virginia
Statistically low chance that it's the PCM. A couple of other items to check are the starter relay itself (it sounded like you
bypassed it to get the starter to crank, but I may have misunderstood), and grounds, both in the cab and in the engine
compartment.

EDIT: On the relay, did you shunt to ground with the key off, or did you ground the relay and then turn the key? If there's a ground problem with the ignition switch, the relay may never be getting the signal to close the circuit. It is possible to have a bad switch off the shelf, too.

Also, are you sure you got the ignition switch gear teeth aligned correctly? Make sure the battery connections are clean and tight,
and that the battery is good. These trucks are really picky with their voltages, and can do some weird things if the battery is marginal.

The backup lights and instrument panel oddities have me thinking ground, though.

Good Luck!

Chris
 

Trchamp

Original poster
Member
Dec 23, 2012
20
When you jump starter it turns over fine. only thing you here is a click under truck like a relay.
 

Trchamp

Original poster
Member
Dec 23, 2012
20
I cleaned the grounds under hood and they all omh out good. The battery is on the charger. I did have a friend hook up a scanner and it will not comunacate with pcm. As for the switch had out many times and adjusted wheel and seen on web how to install so i don't think it is that.
 

Denali n DOO

Member
May 22, 2012
5,596
Trchamp said:
I cleaned the grounds under hood and they all omh out good. The battery is on the charger. I did have a friend hook up a scanner and it will not comunacate with pcm. As for the switch had out many times and adjusted wheel and seen on web how to install so i don't think it is that.

Welcome to GMTNation, Re scanner maybe fuse 13 under back seat is blown...
 

Denali n DOO

Member
May 22, 2012
5,596
Trchamp said:
Checked all fuses and none of them where blown.

Was there a fuse in position 13?
 

christo829

Member
Dec 7, 2011
499
Fairfax, Virginia
Did you check that fuse 13 (If I recall, it's labelled CIGAR) with a meter? Did the scanner just not get signal from the OBDII port?
What kind of scanner was it? Some don't read all protocols.

There have been cases of the fuses getting a slight oxidation on the blades and losing connection, so you might try reseating
the fuse, after checking it for continuity.

What about the grounds inside the cab? The one by the shaft hump is known to come loose, and is worth a check.

Cheers-

Chris
 

Trchamp

Original poster
Member
Dec 23, 2012
20
Where is the one by the shaft hump? Under dash or where thanks.
christo829 said:
Did you check that fuse 13 (If I recall, it's labelled CIGAR) with a meter? Did the scanner just not get signal from the OBDII port?
What kind of scanner was it? Some don't read all protocols.

There have been cases of the fuses getting a slight oxidation on the blades and losing connection, so you might try reseating
the fuse, after checking it for continuity.

What about the grounds inside the cab? The one by the shaft hump is known to come loose, and is worth a check.

Cheers-

Chris
 

Denali n DOO

Member
May 22, 2012
5,596
Trchamp said:
Fuse 13 is there and good just checked and 30 amp

Check that ground that christo829 mentions, passenger side bottom of console/radio stack,
 

Denali n DOO

Member
May 22, 2012
5,596
Trchamp said:
Front or back and is it under it?

passenger side front floor area behind the console panel, my trucks not here to look at...
 

Trchamp

Original poster
Member
Dec 23, 2012
20
Denali n DOO said:
passenger side front floor area behind the console panel, my trucks not here to look at...

I looked under the dash and behind the front area of console and do not see a ground. do i need to remove the console 2004 trailbazer.
 

Denali n DOO

Member
May 22, 2012
5,596

Blckshdw

Moderator
Nov 20, 2011
10,682
Tampa Bay Area, FL
Trchamp said:
I looked under the dash and behind the front area of console and do not see a ground. do i need to remove the console 2004 trailbazer.

When you pull the carpeted panel that's between the center console, and the radio/HVAC stack...

IMAG0476.jpg


... you'll see this splice pack, that everyone is referring to. Hope that helps. :thumbsup:

IMAG0474.jpg
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
I may have missed it, but the fuse you need to check, #13, is under the hood, not the backseat fuse block.
 

Denali n DOO

Member
May 22, 2012
5,596
Wooluf1952 said:
I may have missed it, but the fuse you need to check, #13, is under the hood, not the backseat fuse block.

Oops, ya I said back one in error :redface: it's definitely under the hood..
 

Trchamp

Original poster
Member
Dec 23, 2012
20
I check all the fuses. I pulled out the cpu when you turn the key to run the same thing happens. I am getting a used cpu and trying that. Will it start after i do the relearn ? i know it will need a reflash from the dealer.
 

gmcman

Member
Dec 12, 2011
4,656
Take a hammer or a long piece of pipe and try tapping on the side of the starter case.
 

Trchamp

Original poster
Member
Dec 23, 2012
20
gmcman said:
Take a hammer or a long piece of pipe and try tapping on the side of the starter case.

i grounded out starter relay and it turns over. Check engine light does not come on, bu lights don't work, gas gauge does not work.
 

gmcman

Member
Dec 12, 2011
4,656
Have you checked for voltage at the starter solenoid when the key is turned to start?
 

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