NEED HELP 2002 Chevy Trailblazer no crank
- Thread starter BlueDazing
- Start date
In my haste reading the thread I missed anything about a flashing security light. To me this says you may need to do a 30 minute security relearn procedure.
So how do you jump the starter? Do you remove the starter relay? I am not certain of this but I do know that the PCM can tell if you remove the relay. I cannot say I know if this will cause a security issue as I have never tried that.
When I first bought my 2002 it had an intermittent no crank situation. For about a year I had a mechanics starter jump switch attached at the starter between battery power and the starter S terminal. I actually left the switch on my dashboard and when the starter failed to crank by the normal means I would hit the mechanics switch and be on my way
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Yes, it allows me to read and delete codes, but when I scan with it, it reads no codes.
I will add that back in the day while I had starting issues,,, occasionally in trying to jump things I would trigger some sort of security lockout. After that it would crank fine but not fire. These times I would need to wait like 10 minutes or more for that timer to expire and then it would start OK,
assuming the starter cranked or I used my mechanics switch as previously described.
I never experienced the engine firing and then dieing though. That sounds like a possible issue with security involving the fuel continue password. When on the occasion that you get it to fire but it then dies out what does the security light show at the point the engine stalls out but you have NOT yet turned the key away from RUN?
assuming the starter cranked or I used my mechanics switch as previously described.
I never experienced the engine firing and then dieing though. That sounds like a possible issue with security involving the fuel continue password. When on the occasion that you get it to fire but it then dies out what does the security light show at the point the engine stalls out but you have NOT yet turned the key away from RUN?
That switch is exactly what I have, but when I start the truck with it, it cranks, starts, and shuts off after 1 second, followed by the security light coming on and blinking.
I don't think there is anything you can do at the BCM short of verifying the connectors are good and nothing looks like it spilled onto any of the connections.
I've done a security relearn at one point with a timer, and it finished exactly at 10 minutes. But when i let the light do its thing after using the mechanic starter switch, i left it blinking for a good 15 minutes and it didnt shut off.
I did have the door open that time though if that changes anything.
And the starter relay is in place in the fuseblock?
And you only use the switch after turning the key to the start position?
The security light does not flash after turning the key to start? But starts flashing after you hit the mechanics switch?
It is a Damned Shame that you don't have access to a Good Scan Tool capable of reading Class 2 (UXXXX) and Body Module (BXXXX) Codes. THIS interaction is both On Topic and Interesting:
I am trying to think but nothing happens!
I just come up with random somewhat related thoughts but nothing that really seems to fit your current situation.
It's the flashing security light that troubles me as it shouldn't do that given the order of operations I previously stated. If the light began flashing when you turned the key to start position that would mean Passlock issue. But to only start flashing when jumping the starter is not something I can explain. Not to even mention flashing in a repeating pattern instead of a constant.
Have you checked the tightness of the individual terminal sockets for the relay?? You can maybe do this without special tools by sacrificing a fuse. Cut it in half vertically with a wire snips or by some other means so that you then have a single male terminal that you can use to insert into each socket to see that it is a tight fit with good resistance to pulling it out. My fuseblock had been damaged by previous owner sticking meter test leads and such in the sockets. This loosens the connection of the relay to the fuseblock. That led to my intermittent crank issue.
Back in the start of this thread you speak of relay terminal #87 being grounded. This should be the lower right terminal. It goes to the starter solenoid. It should read a low resistance but not actual ground as it reads through the starter solenoid coil winding.
Now the terminal #86?, Lower left socket will normally read open, but it 'might' read about 48,000 ohms when reversing the test leads.
Ok, this needs clarification here.
It sounds like you did ONE ten minute cycle of the security relearn and the light went off.
But then you talk of using the mechanics switch. That is NOT the procedure.
When the light went out did you then turn the key OFF for at least ten seconds or more and then turn it back on and try to start the truck normally?
And after the second time the light goes off after a second ten minutes? And again you turn the key to OFF and wait at least ten seconds?
And then a third time you again try to start the truck manually and the security light goes on and again you wait 10 more minutes and the security light turns off??
At NO time during this should you be using the mechanics switch.
The only time I've needed to do a security relearn, was when I attempted to disable the Anti-Theft (as a way to get the truck to stay running when using the mechanic switch) by snipping the yellow wire that is usually used to place a resistor, I'd seen a YouTube video where the guy just snipped it and was able to start his truck even with a solid security light on.
It didn't work, so I put the wire together and thats when the security light was blinking. I tried the security relearn by turning the key off, setting a ten minute timer on phone and starting the timer at the same time that I turn the key to run.
The security light turned off at exactly 10 minutes, and I did turn the key to accessory for 10 seconds before turning it back to run, but the security light was not flashing anymore at this time, so I did not repeat the process x3.
I did not immediately use the mechanic switch after this, as I did not think anything had changed anyway. But I did try to start the truck with the key when i realized the security light was not coming back on, but that did not work.
For terminal #87, the lower right, my test light lights up, only when I have the ground clip hooked up the the positive side of the battery.
So I assume hooking the alligator clip up to the positive side, reads ground but i could be wrong. The light for using the positive side on my test light is green, but when hooking up the clip to the negative side, it is red.
When hooked up to the negative side, the top 2 terminals light up red, and also read 12v on the meter, but the bottom two terminals are blank.
When hooked up to the positive side of the battery, the top 2 terminals are blank, and the bottom left is blank as well. But the bottom right lights up with green. I have not used the multimeter on that terminal before, but I don't think it will read anything if all the test light is showing is ground.
Trust me, I know.
As far as that post goes, I actually have the same buzzing noise that sounds for a brief moment when putting the key in run. It only last around a second or two though.
That might have actually been when my battery was low though, I hooked it up to the charger and I'm not sure if it does that when the battery is fully charged or not.
BCM was fine, big red 12v wire was reading 12v, fuses had power and the weird box on the front side of the fuse panel was humming with electricity, so I assume it's all working. It all looked clean too.
just to confirm, you turn your key to on then do the "workaround relay thing" and vehicle starts but stops shortly thereafter even though the key is still in ON. You get a flashing theft when it dies. The BCM has to be happy for it to tell the PCM that it is OK to start. IF that doesn't happen, the PCM will never try a start. So I would have expected that a key on would normally allow a "wire jumped" system to start and run.... if the key recognition circuit is good. That circuit runs to the bcm. You should check voltages at the bcm (which I think is in the rear by the fuse box).
Its too bad you don't have working fobs (ie. programmed) as then you could see if you can cause a door lock unlock to confirm that the BCM is somewhat happy. Anyway, visual check of connections at the bcm is needed at very least.
OOPS I see you posted in front of this.
there is some difference between the previous owners "work around / switch" and yours since I assume the truck ran for him..
You likely need to get at the ignition switch and check out the key detection wiring which goes to the bcm
You likely need to get at the ignition switch and check out the key detection wiring which goes to the bcm
Also, I can program a fob for the truck, I have 2 fresh key fobs that have never been programmed. They were just cheap ones on eBay, not really designated for any specific vehicle.
The "Weird Box" mounted on the side of the Fuse Block, hovering at Right Angle in that B&W Line Image I posted IS "The BCM".
I think this test results confirms that the key is being detected correctly. I guess that might be true as perhaps the BCM doesn't detect and engine "hot wire" until the rpm is detected and then if the key wasn't detected, it sets the theft and disables fueling.
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I understand now. It seemed to be in order, I could hear electricity running through it with my ear close enough, all of the wires coming out of it were clean, is there anything specific I can check with it?
the tests that you did as suggested by tjbaker which had the keying done at certain times in the sequence.
One other thing... Whoever it was that "Franken-BCM-ed" this SUV may have had to install more Non-Standard Components and Wiring elsewhere inside the Vehicle. So whenever convenient, taking some images around these Main Players can help in figuring things out:
(1) The PCM (looking for sliced open harness sheathing on the Three Connectors)
(2) The BCM and The Under-Seat Fuse Box
(3) The Under-Hood Fuse Box (as is)
(4) The Open Underside of the Steering Column at the Ignition Switch
We're looking for any obvious Non-Standard Wiring and-or Cheap, Glossy Black Electric Tape or Butt-Connectors out of place. Also... ANY kind of after-Market Security and-or Remote Start Gear hooked in under the Dash Board or around the Engine Compartment where things should not be. Staged Images of these areas might give more insights into other things that might be 'amiss'.
(1) The PCM (looking for sliced open harness sheathing on the Three Connectors)
(2) The BCM and The Under-Seat Fuse Box
(3) The Under-Hood Fuse Box (as is)
(4) The Open Underside of the Steering Column at the Ignition Switch
We're looking for any obvious Non-Standard Wiring and-or Cheap, Glossy Black Electric Tape or Butt-Connectors out of place. Also... ANY kind of after-Market Security and-or Remote Start Gear hooked in under the Dash Board or around the Engine Compartment where things should not be. Staged Images of these areas might give more insights into other things that might be 'amiss'.
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one more thing, at the start of this thread, you indicated that fuse 17 had voltage but that doesn't mean it is getting to the PCM.
Pull fuse 17, find out which side of the fuse holder / position get the 12v. Go to the other side and do a impedance measurement (to ground). You should get some reading, not 0 and infinity.
Pull fuse 17, find out which side of the fuse holder / position get the 12v. Go to the other side and do a impedance measurement (to ground). You should get some reading, not 0 and infinity.
Accesory is NOT OFF !!
OFF for no less than ten seconds.
And the ten minute timer MUST be done at least 3 times.
The PCM, that switch coming out of the starter, the fuse box, the backseat fuse box, and BCM.
The dust on the fuse box is from leaving it open these past few days.
Those 2 blue butt connectors at the ignition switch are from when I was messing with the anti-theft wire. I had picked the wrong yellow wire at first, that's why there are 2.
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I'm confused, it did end up getting the security light to stop.
I could redo the process, but the security light isn't on, so I'm not sure if it will be effective.
When I pull the fuse out, the socket closest to the starter relay gets 12 volts when the key is in crank, it gets 0.11v when the key is in run. The next socket gets 0.01-0.02 with the key in run and in crank
Almost but not quite what I suggested. You determined which pin on the fuse block has 12v ... good. I then asked for you to take an impedance measurement (resistance) on the other pin (to ground). The reason for doing it this way is that if you take a impedance measurement on a powered pin, you can destroy your meter.... so you need to know which pin is powered and which is not. Further, for the impedance test, the key is OFF. You are not looking for voltage, you are looking for circuit continuity to ground like conditions.
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