SOLVED! Trailblazer not starting please help

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
Hello long time no post. So since I bought the TB it's always had a problem of sometimes I have to turn the key back off and then start, last time it ran I had to disconnect the battery to get it to start back up. Since then it wont do anything. I was sure it was the security system so I mailed if off to pcmofnc and still no start. I dont hear a starter noise, it has been parked for a while and now when I try to jump it nothing goes and instantly loses charge when I disconnect the jumping car, I just learned today I could probably start the car by without a key (ignition can be hand turned all the way to start without a key), I'm so frustrated and just need direction. Thanks so much in advance
 

Chemman

Member
Jul 13, 2013
35
Maryland
Have you considered replacing the ignition switch? It's known to have a high failure rate and to cause numerous strange behaviors including a no start condition.
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
Have you considered replacing the ignition switch? It's known to have a high failure rate and to cause numerous strange behaviors including a no start condition.
In the past yes with having to turn it off just to try and start it again. Could I ontop of that have a dead battery since it loses charge so fast after being disconnected from the jumping car or could that just be because it's not running and charging off the alternator?
 

christo829

Member
Dec 7, 2011
497
Fairfax, Virginia
When you turn the key to the run position, do you hear the fuel pump prime up? Should give you a roughly two second whine then stop. I don't think the pump is your problem. I'm asking because it would indicate that the pump is getting the proper signal. If it's *not* priming, I'd lean more towards the ignition switch being bad. These can be bad out of the box, or the gear teeth can be slightly misaligned during installation, so even if you've replaced it in the past, it would be a cheap and easy item to check off the list.

Yes, a bad battery would cause equally flaky behavior.

Next place to check would be your starter relay.

Good Luck!

Chris
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
When you turn the key to the run position, do you hear the fuel pump prime up? Should give you a roughly two second whine then stop. I don't think the pump is your problem. I'm asking because it would indicate that the pump is getting the proper signal. If it's *not* priming, I'd lean more towards the ignition switch being bad. These can be bad out of the box, or the gear teeth can be slightly misaligned during installation, so even if you've replaced it in the past, it would be a cheap and easy item to check off the list.

Yes, a bad battery would cause equally flaky behavior.

Next place to check would be your starter relay.

Good Luck!

Chris
I honestly can't remember on the pump. Yesterday was the first time I've been able to mess with it in almost two months and it wasn't for very long, dont even think I was listening for it. I ordered a new ignition switch this morning that should be here Thursday. The starter relay is just the fuse right?
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
New ignition switch and still no. I heard the fuel pump prime at first time I turned the key but not again after that not again, we hear a click under the circuit board, I don't hear the starter, no cranking. These are what the dash show when its put to on.
 

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TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,047
Brighton, CO
The security light is on. You have other problems. Dont know much about that system as I dont have VATS.
 

TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,047
Brighton, CO
Do you have any extra keys for your truck? If you do, start there. With that security system light on, it wont start.
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
Do all these lights remain on as long as the key is in the ON position, or do some of these lights flash on for a second or two then some go off?
So I'll try and start it and they all go away for a split second, the battery comes and then the traction control, lock, and temperature lights come on after a second and just stay
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
Right under what? The truck? The fuse box under the hood? The steering column? The dashboard? You have given no idea of exactly where or what the click you hear is located!
Fuze box, I worded it wrong when I said circuit board I was still in my work mode so I called it the wrong thing.
 

TJBaker57

Member
Aug 16, 2015
2,897
Colorado

Aha! If you're reliably getting a click there when you turn the key to start that's a good sign. The starter relay is there. The starter relay when closed should send a 12volt signal down the the starter. The pin connections from the fuses and relays in the fusebox are known to be trouble spots. You could try wiggling them in their sockets do you have the wiring diagrams and know how to read them?
 

TJBaker57

Member
Aug 16, 2015
2,897
Colorado
battery comes and then the traction control, lock, and temperature lights come on after a second and just stay

It is mainly the security light I was wondering about. I think the normal behaviour is for it to flash on for a second or 2 when you first turn the key to ON, then the light goes out. If the security light is staying on there may be trouble with your anti theft system. I think you mentioned the switch turns without a key in it? You mentioned sending out the PCM for something related to the security system. If I remember correctly it is the BCM (Body Control Module) that does much of the security.
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
Aha! If you're reliably getting a click there when you turn the key to start that's a good sign. The starter relay is there. The starter relay when closed should send a 12volt signal down the the starter. The pin connections from the fuses and relays in the fusebox are known to be trouble spots. You could try wiggling them in their sockets do you have the wiring diagrams and know how to read them?
I do not have them and I watched a video of a guy troubleshooting his and it doesn't seem super difficult
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
It is mainly the security light I was wondering about. I think the normal behaviour is for it to flash on for a second or 2 when you first turn the key to ON, then the light goes out. If the security light is staying on there may be trouble with your anti theft system. I think you mentioned the switch turns without a key in it? You mentioned sending out the PCM for something related to the security system. If I remember correctly it is the BCM (Body Control Module) that does much of the security.
I might be wrong but I wonder if that was happening because the battery was disconnected and that locking pin just wasn't working because of that. It wasn't doing it after the battery was back connected. Yes I did and they said they would be more than happy to double check it but I'm hoping to try other things first so I dont have to wait for it to get there and back
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
So I watched a video and the guy was messing with the harness that plugs into the switch sensor and that worked. Anyone else ever have that happen? I'm working so I can't try right now
 

TJBaker57

Member
Aug 16, 2015
2,897
Colorado
Wiring diagrams can be found here in the service manuals.
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
Oh I might have that then but if not or either way thank you. Just go through with a test light checking all areas along the path of current?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
All the lights, including the security light, come on for a couple of seconds on the RUN position during bulb test and most should go out, including the security light. If it's staying on, then there's something wrong there. Maybe try to do a security relearn.

Your battery dying so fast without actually cranking is a bit suspect. Did you get it tested? That could be a source of your troubles with a weak battery.
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
All the lights, including the security light, come on for a couple of seconds on the RUN position during bulb test and most should go out, including the security light. If it's staying on, then there's something wrong there. Maybe try to do a security relearn.

Your battery dying so fast without actually cranking is a bit suspect. Did you get it tested? That could be a source of your troubles with a weak battery.
That was my next move. I'm going to test it hopefully today and buy a test light to test my switch to see if it came faulty. I haven't driven the car in probably two months now so I'm not sure if its normal but my stereo stays on when I try to start it but the orange lights on my 4x4 control turns off when I try to start it. Dont know if that's normal or showing my battery is toasted. Couldn't it still try to start though hooked up to a car jumping it or could it be so far gone that it wouldn't even though its showing it has power when being jumped? Also it doesn't have the marker anymore showing what gear I'm in on the cluster but from reading that could just be normal because the neutral safety switch isn't commonly a problem?
 

Blckshdw

Moderator
Nov 20, 2011
10,665
Tampa Bay Area, FL
my stereo stays on when I try to start it

This could possibly be the RAP (retained accessory power) circuit. It will keep power to the windows and radio for 10 minutes after the ignition is shut off, or until one of the doors/lift gate is opened, whichever happens first. If you try starting the truck with any of the doors open, and the radio STILL stays on, then that's another issue.

it doesn't have the marker anymore showing what gear I'm in on the cluster

It's possible that your display has died. It's not a problem that gets reported on here frequently, but it does happen. I don't think anyone's been able to fix it themselves so far. When it happened to mine, I got a used junk yard cluster (DIC upgrade :biggrin:), and had the mileage programmed by a speedo repair shop that was local.
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
This could possibly be the RAP (retained accessory power) circuit. It will keep power to the windows and radio for 10 minutes after the ignition is shut off, or until one of the doors/lift gate is opened, whichever happens first. If you try starting the truck with any of the doors open, and the radio STILL stays on, then that's another issue.


Okay so if it stays on did I just wire it wrong or my switch is off a tooth? What about the light indicating If I'm in 2wd, 4low etc turning off when I try to start it? I've only been able to try and jump it during day so I haven't seen if my lights dim.

Sorry about all the odd questions but I've seen on other threads people asking if they tried starting it in neutral, what does that do or how does that help figure the problem out?
 
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Blckshdw

Moderator
Nov 20, 2011
10,665
Tampa Bay Area, FL
My truck is 2WD so no experience troubleshooting the 4WD system.

Did the radio issue just start happening when you swapped in the new ignition switch? If so, then it's possible that it's off by a tooth.
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
My truck is 2WD so no experience troubleshooting the 4WD system.

Did the radio issue just start happening when you swapped in the new ignition switch? If so, then it's possible that it's off by a tooth.
Honestly I can't remember because it's been down for like two months. Idk if my switch is defective or if it's me but I haven't been able to spin the wheel enough for just one tooth to move. It's always like a quarter turn
 

TJBaker57

Member
Aug 16, 2015
2,897
Colorado
just when you turn it to start you hear a click noise


With regards to the park/neutral switch, ignition switch and such let me reiterate,,, if the starter relay (#47) in the fuse box clicks every time you turn the key to the start position this in itself proves that the park/neutral switch and the ignition switch are working correctly at least as far the starter is concerned. You can see this in the wiring diagram. The signal telling the PCM to engage the starter relay comes to the PCM through the crank fuse from the ignition switch. This tells the PCM that you wish to start. The PCM checks for a signal from the Park/Neutral switch. This signal can also be seen in the same wiring diagram where 12volt power comes through the ign E fuse down to the Park/Neutral switch then back through the fuseblock and on to the PCM. If the PCM does not see both of these it will not command the starter relay to engage and you will not hear the click in the fusebox.

If I were troubleshooting it at the stage where the starter relay in the fusebox clicks but the starter does not engage I would do the jumper as directed in the video I linked in my last post. The video author cautions and I will concur, do not stick test light probes or other such items down into the fuseblock. They are too thick and will likely do damage to the connectors down in the hole. The relay terminal pins are just 0.7 mm thick, even a standard small paper clip is thicker than this. If larger things are stuck down there they will likely spread the connector apart then the relay will have poor or no connection to the fuseblock resulting in intermittent no crank conditions. This I know firsthand as my TrailBlazer was in this condition when I bought it.

Now as for the security stuff,,,I have no idea what is done to a PCM to remove the VATS stuff so I can only speak of a standard system ....I may be wrong but I think the PCM will not command the starter relay on before getting an OK from the BCM saying essentially that the ignition switch has been turned using a good key. So again, if the starter relay is clicking then this appears to be OK. HOWEVER,,,,, the security can still cutoff the fuel supply AFTER the engine starts if other security related things don't check out right. But you're not there yet. You are not even cranking so that should be the first priority.

Battery issues. You said the battery loses charge as soon as disconnected from the jumper vehicle. If your battery is poor or dead this is normal behaviour. Your battery will not charge up when hooked to a jumper car unless it is hooked up to a running car with a good electrical system for at least an hour or more. And this is not anything I could recommend as it is bad for the donor cars charging system. The purpose of jumping is only to get the dead car started. A discharged battery needs to be charged on a battery charger for at least an hour or more. So if your battery is in poor charge that needs to be addressed. Even with a good donor to jump from, if the jumper cables are not heavy enough and the connections are not quite solid enough at the batteries you can get a big enough voltage drop (loss) to cause the sort of things you are seeing. You hook it all up, turn the key to start, the system does all it is supposed to and when the big load of the starter tries to engage it draws too much current through the bad connections of the jumper cables or the cables just are too small and the voltage drops down to where there is not enough power at the dead car and the system resets and the whole thing repeats. This is what causes that click,click,click,click you sometimes hear when trying to jump start a vehicle.
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
Okay so update battery is toast. I'm hoping tonight I'll have time to mess with it but it's also back burner to my wife's car work. So if I do try to jump start the starter like the video says and nothing happens is there any chance that it could be the security system locking the car down or no?
 

Blckshdw

Moderator
Nov 20, 2011
10,665
Tampa Bay Area, FL
If the security light turns off after the initial check when turning the key, and stays off, then it's not part of the equation.
 
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MBS1994

Original poster
Member
May 26, 2019
326
Colorado
Okay did the starter test and it tries to crank so that's good and it got it's new battery. So I'm I right in thinking it could be the starter relay or fuel pump related
 

Blckshdw

Moderator
Nov 20, 2011
10,665
Tampa Bay Area, FL
Okay did the starter test and it tries to crank so that's good and it got it's new battery. So I'm I right in thinking it could be the starter relay or fuel pump related

You already told us those things are working properly when you posted this earlier... Check to see if you can hear the fuel pump priming again, the starter won't engage if there's a problem with the relay. So that's ruled out for good.

I heard the fuel pump prime at first time I turned the key but not again after that not again, we hear a click
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
You already told us those things are working properly when you posted this earlier... Check to see if you can hear the fuel pump priming again, the starter won't engage if there's a problem with the relay. So that's ruled out for good.
Earlier was absolutely nothing I had just got the battery and tested the starter right before I posted. I had not done any of that prior
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
Okay so starter is good, new relay, new switch, new battery, has gas, security light only goes on with my wife's key and now when its locked, I do not hear my fuel pump, switched ac fuse with the fuel pump and still nothing.
 

MBS1994

Original poster
Member
May 26, 2019
326
Colorado
Side note thinking about it. The cluster shows the stabilatrack warning, the 4x4 warning, and low oil/coolant. Could any of that be part of the problem?
 

TJBaker57

Member
Aug 16, 2015
2,897
Colorado
did the starter test and it tries to crank

Different folk have different ideas of what "crank" means. (I can be an old crank but that is another story) Among mechanics "cranking" means the starter is spinning the motor. "Tries to crank" to me means the starter engages and attempts to spin the engine but maybe the battery has not the power to get it really turning. Is this what you mean here?

security light only goes on with my wife's key and now when its locked

I do not understand the "now when it's locked" part. What is locked?

Okay so starter is good, new relay, new switch, new battery, has gas
When you say "has gas" do you mean has gas in the tank, or do you mean you can hear the fuel pump running?

cluster shows the stabilatrack warning, the 4x4 warning,

These warnings will not affect the starting in any way
 

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