02 Trailblazer won't start

jbus1982

Original poster
Member
Jan 24, 2012
8
I have a 02 Trailblazer. The other day I was having starting issues. Really slow crank. New battery, alternator and the starter checked out good. Replace the negative battery cable and cleaned the positive connections. Vehicle started right up. Let up run for 10 minutes. Took it for a test run and right out of my driveway I rolled up the window and it stalled. Started it again ran for a second and stalled. Started it again died right away. Tried to start it agian and it just cranks with no start. Also dont know if this is related but there is a weird noise in the dash when I turn the key to start position. It has no codes.
 

mika

Member
Dec 6, 2011
82
I agree, checkto see if you have spark, as you pull the plugs check to see if they smell of gas. Another silly question, you do have gas in the tank right??
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
And ignition switches have a high failure rate, and could show those symptoms. Any other maintenance history? All 100K maintenance done on time?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
One circuit on the ignition switch is only active on the START position, and that's what could be spinning the starter. However, there are other circuits active in the RUN position that aren't on in START that could cause a stall. Our ignition switch is pretty complex, with two fused inputs and FIVE outputs.

For completeness in case you want to drag out a meter and check yours:

RED on the ignition switch is 12V, fused by underhood fuse #34, and feeds the following three circuits:

White is hot in ACCY, RUN, START
Orange is hot in RUN
Yellow is hot in START

RED/WHITE is another 12V, fused by underhood fuse #36, and feeds two circuits:

Brown is hot in ACCY, RUN
Pink is hot in RUN, START

Do you have a meter and are you troubleshooting this to the root cause yourself? How much detail do you want to be getting into?
 

jbus1982

Original poster
Member
Jan 24, 2012
8
I have multimeter. I took it to the dealership and they said it was a bad fuel pump. Change the fuel pump last night it running. Then today it started for 5 seconds then died started 5 more times for 1 second and died. Know it just cranks. Now I dont here the pump at all. Could this be an ignition switch
 

smitty5150

Member
Nov 18, 2011
1,069
the roadie said:
Assuming you PAID the dealer for a diagnosis, didn't it come with a guarantee they were right?

:iagree:

I say IGN switch without you having tested because you claimed to rule out the other possibilities. I have replaced mine and it presented the same symptoms. I also had an issue with some of my accessories not working...windows/radio/etc. Did you experience any of this? Once started I would stay running, but the gauges would occasionally die as well.
 

jbus1982

Original poster
Member
Jan 24, 2012
8
Changed ignition switch. Couple questions. Do u have to change the key lock as well? The gears have to right or it won't turn over? I put the new one in and no luck. I'm still not hearing the fuel pump come
 

jbus1982

Original poster
Member
Jan 24, 2012
8
how do i go about using a multimeter to check the ignition switch. new to using a multimeter
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Got any local friends who do? Much more efficient to buy them beer and get somebody to talk to in real time, rather than folks on a forum. Did you try fiddling the gear teeth positions yet? Does the vehicle respond as you think it should in the ACCY and RUN positions, just not the START position?

Or is the issue the same - it cranks OK in the START position, but the engine doesn't ignite and run?

You really dropped the fuel tank last night and changed the fuel pump? Alone? :confused: :eek:
 

jbus1982

Original poster
Member
Jan 24, 2012
8
yea. i think i found the gears. it acts normal until the start up when it just cranks and doesnt start. Ive been watching a lot of tutorials on youtube today trying to figure out basics of checking wiring. Kinda thinking it might be bad ground on the pump. Rip offs at the dealer said when they pounded on it the pump ran. Yea the tank was half full. Amazing what you can construct in your garage for a lift when you put your mind to it. does the key have to be turned to check the voltage at the ignition switch. Im bound and determined not to pay anyone anymore money to fix this thing. Thanks for your replies. I appreciate it
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
I think you have to go back to basics or get a mechanic you can trust to work on it.

Fuel
Air
Spark

Check each of those items during an attempted start.

Guessing a PCM at this point is pointless. We're not with you expect in spirit. You need somebody with some experience to lay hands on the vehicle. There are a dozen fuses it could be even, but I assume you checked each of them with a meter. Relays are harder to check, but the fuse block full of them.
 

jbus1982

Original poster
Member
Jan 24, 2012
8
I figured it out. Bad ground for the fuel pump. Ran a new ground into the engine compartment. Thanks for all the help
 

MichEnvoyGuy

Member
Dec 3, 2011
522
jbus1982 said:
I figured it out. Bad ground for the fuel pump. Ran a new ground into the engine compartment. Thanks for all the help

Glad you got it fixed and this provokes me to check my fuel pump ground. I have no problems ((yet)) but nothing like a little preemptive preventative maintenance right?

Roadie, where is the fuel pump ground located? Dont you have all those fancy schmancy electrical diagrams? :biggrin:
 

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