SOLVED!-04 Trailblazer LT 4.2 L no crank - no start

coolasice said:
You said earlier it had power in both run and crank...


without power during crank it cant turn on the relay
Click to expand...

SO sorry. Not sure if the wife understands the difference between run and crank. 86 is energized in crank ONLY. No power on 86 in Run...should it have?
Took my daughter out there with me this time and repeated last night's test probing 85 with light connected to POS Battery. It again illuminated faintly and stayed on for 20 seconds or so. I apologize for the previous response which was incorrect. Again, 86 is only energized in the crank position. 87 always hot.

EDIT: Looking at the starting system wiring diagram, 86 looks to only be HOT in the crank position.
 
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Rad said:
SO sorry. Not sure if the wife understands the difference between run and crank. 86 is energized in crank ONLY. No power on 86 in Run...should it have?
Took my daughter out there with me this time and repeated last night's test probing 85 with light connected to POS Battery. It again illuminated faintly and stayed on for 20 seconds or so. I apologize for the previous response which was incorrect. Again, 86 is only energized in the crank position. 87 always hot.

EDIT: Looking at the starting system wiring diagram, 86 looks to only be HOT in the crank position.
Click to expand...
86 should have power in run AND crank
 
You are absolutely correct...I followed the incorrect path to crank fuse 17. The diagram clearly shows that 86 should be hot in run and crank!!! So why isn't it hot in Crank?

Voltage travels through the neutral safety switch before it reaches the relay but manages to get HOT in Run. Could it be that the reason it is hot only in Run that 86 gets 12V through the green wire out of the PCM from pin 29 and doesn't get the 12V in crank because voltage is not making it through the neutral safety switch with key in the crank position?
 
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Rad said:
You are absolutely correct...I followed the incorrect path to crank fuse 17. The diagram clearly shows that 86 should be hot in run and crank!!! So why isn't it hot in RUN?
Click to expand...
I would test it again... just you, no helpers, just put key to run and test for voltage...
 
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coolasice said:
I would test it again... just you, no helpers, just put key to run and test for voltage...
Click to expand...
My helpers are no help! Here is what happens! Key in RUN, 86 is HOT. Key in crank, 86 is NOT HOT. This puts a whole new twist on it. Checked that a couple of times!

EDIT: I apologize for adding a bunch of confusion to the last few responses concerning socket 86.
 
Rad said:
My helpers are no help! Here is what happens! Key in RUN, 86 is HOT. Key in crank, 86 is NOT HOT. This puts a whole new twist on it. Checked that a couple of times!
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OK... Then I think your ign switch is off a tooth...

Is 86 hot in acc position?
 
coolasice said:
OK... Then I think your ign switch is off a tooth...

Is 86 hot in acc position?
Click to expand...

No, it is only HOT in Run. Just went back out and checked...crank fuse 17 is energized when pushing key to crank position. I doubt the switch is off by a tooth.

@coolasice - looking at the wiring diagram where the yellow and green wires merge, both lead to the starter relay at 86. Could it be that the crank signal through the green wire is not making it to that point resulting in a no crank condition since 86 becomes "cold" when pushing the key to crank?

EDIT: Or...could it be that the neutral safety switch is not allowing fuse 22 voltage from the pink wire to reach the yellow wire leading to the relay?
 
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Have you tried a fresh set of relays?

Did you remove the panels to VISUALLY CHECK for remnants of an alarm system?

If not, pull the panels, grab a flash light, and check it out.

Try the valet key, and try another master key.

Try this and report back.
 
Also, I.keep.mentioning an aftermarket alarm, I also mean to say an aftermarket remote start.

Unless you're 100% sure it's not in there, make sure you thoroughly check it out.
 
Rad said:
No, it is only HOT in Run. Just went back out and checked...crank fuse 17 is energized when pushing key to crank position. I doubt the switch is off by a tooth.

@coolasice - looking at the wiring diagram where the yellow and green wires merge, both lead to the starter relay at 86. Could it be that the crank signal through the green wire is not making it to that point resulting in a no crank condition since 86 becomes "cold" when pushing the key to crank?

EDIT: Or...could it be that the neutral safety switch is not allowing fuse 22 voltage from the pink wire to reach the yellow wire leading to the relay?
Click to expand...
I would go back to the ignition switch and test the pink wire out of it, should be hot in run and start...
 
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gmcman said:
Also, I.keep.mentioning an aftermarket alarm, I also mean to say an aftermarket remote start.

Unless you're 100% sure it's not in there, make sure you thoroughly check it out.
Click to expand...

I took a pretty good look under the dash when I had the lower driver side panel removed to replace the ignition switch. I didn't see any evidence of splicing and residual remnants hanging from factory wires. Also no evidence of sloppy electrical taping. But, I will take another look tomorrow.
 
The white paper towel test for trans fluid contaminating the connection is a good suggestion, I'm very curious as well as many here.

Also, don't forget to try other keys to rule out a pass lock issue....I'm pretty sure these have the pass lock key...dunno for sure.
 
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coolasice said:
I would go back to the ignition switch and test the pink wire out of it, should be hot in run and start...
Click to expand...
Will do so tomorrow. I did check all the ignition switch wires earlier in my testing and they behaved as they should. I will take another look since I just revisited the ignition switch yesterday but did not perform another voltage functional check thereafter.
I think that we are a step closer to solving this issue especially since we now know that 86 only shows HOT in Run and not in both, Run and Crank.
My greatest appreciation to your efforts as well as everyone else's who has spent their precious time with me sorting through this.

But my time off from work ends today and I have to call it quits for tonight. Alarm will rattle my brain at 04:30 AM. I will check the ignition switch voltages tomorrow after work (although it will be dark by the time I come home). I will report back with my findings.
 
gmcman said:
The white paper towel test for trans fluid contaminating the connection is a good suggestion, I'm very curious as well as many here.

Also, don't forget to try other keys to rule out a pass lock issue....I'm pretty sure these have the pass lock key...dunno for sure.
Click to expand...
No chips on the keys. The passlock sensor is mounted on the ignition switch lock cylinder housing. The wife has been using a LOWES cut key for about one year now without any issue. So, nothing special about the key itself (I think).
 
Definitely wouldn't hurt to try another original key.....just to rule it out.

So am I understanding this correctly.....everything worked fine until you had a dead battery one day?
 
gmcman said:
Definitely wouldn't hurt to try another original key.....just to rule it out.

So am I understanding this correctly.....everything worked fine until you had a dead battery one day?
Click to expand...
Not exactly sure what happened. It's the wife's truck and as stated, she drove it early in the morning, made a 10 minute stop, got back in the truck and it wouldn't start. She couldn't move the shifter out of park when I asked her to try starting it in neutral (the button on the shifter wouldn't push in). She left the truck and got a ride to work. When I went to check it out after work, the same condition existed. I noted that the speedometer and RPM gauges were jumping around mid travel with the key in run - very strange. Noticed that the interior lights were dimmer than normal so I tried jumping it. After messing with the jumper cables, for awhile between the two vehicles until I felt I had a good connection, I went and tried to start it. The 1st thing I noticed was that when stepped on the brake pedal that I could hear the shift solenoid now clicking at which point I was able to shift the gears. Tried to start it and managed to get it started (but not immediately until I messed with the jumper cables some more). I moved the truck to a different spot in the parking lot, shut it off and restarted it. Went home, got some tools and the wife to bring the truck home. Wouldn't start again. Battery terminals were tight. Broke out the jumper cables and managed to get it started again. Each time I got it started, the gauges no longer jumped. Got it home, would not restart again even with a jump and fully charged battery. Changed ignition switch and gauges no longer jumped. Had old switch in and out, and gauges jumped around every time the old switch was in. Been at it since. Didn't really want to type all this since I pretty much covered it in my intro to the problem, but that's about the just of it. All the chasing done to this point is posted.
 
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"We Batter these Demons Back into the Darkness...with OUR COLLECTIVE MINDS..."

Bono Notte
 
Ok...., I did read the opening post but wasn't 100% sure that this was the 1st time it acted up. I wonder if the new ignition switch is faulty? Have you tried another one? Perhaps one from a salvage yard?

The fact the new one stops the gauges from jumping around sounds like you are on the right track.
 
Rad said:
Will do so tomorrow. I did check all the ignition switch wires earlier in my testing and they behaved as they should. I will take another look since I just revisited the ignition switch yesterday but did not perform another voltage functional check thereafter.
I think that we are a step closer to solving this issue especially since we now know that 86 only shows HOT in Run and not in both, Run and Crank.
My greatest appreciation to your efforts as well as everyone else's who has spent their precious time with me sorting through this.

But my time off from work ends today and I have to call it quits for tonight. Alarm will rattle my brain at 04:30 AM. I will check the ignition switch voltages tomorrow after work (although it will be dark by the time I come home). I will report back with my findings.
Click to expand...
The ignition switch is the only known common change from working to non working truck. It is the only thing that could be cutting power off from pin 86 when turning the key. The power coming from the ignition switch needs to be tested on all output leads to be 100% positive it is correctly installed
 
coolasice said:
The ignition switch is the only known common change from working to non working truck. It is the only thing that could be cutting power off from pin 86 when turning the key. The power coming from the ignition switch needs to be tested on all output leads to be 100% positive it is correctly installed
Click to expand...

I agree, it's cheap insurance to try another switch after the OP checks this one out, cheaper than a trip to the shop.
 
gmcman said:
Ok...., I did read the opening post but wasn't 100% sure that this was the 1st time it acted up. I wonder if the new ignition switch is faulty? Have you tried another one? Perhaps one from a salvage yard?

The fact the new one stops the gauges from jumping around sounds like you are on the right track.
Click to expand...

Will go out and buy another. It's just to damn cold today to mess with it. Thanks

coolasice said:
The ignition switch is the only known common change from working to non working truck. It is the only thing that could be cutting power off from pin 86 when turning the key. The power coming from the ignition switch needs to be tested on all output leads to be 100% positive it is correctly installed
Click to expand...

Thanks CoolasIce - just couldn't recheck today. 1st day back to work since before XMAS and it's freezing out. Tomorrow doesn't look much better as far as temperatures go. Will go ahead and buy another switch. I agree, just because the switch is new doesn't mean that it's not faulty.

gmcman said:
I agree, it's cheap insurance to try another switch after the OP checks this one out, cheaper than a trip to the shop.
Click to expand...
Agreed. Thank you!
 
coolasice said:
The ignition switch is the only known common change from working to non working truck. It is the only thing that could be cutting power off from pin 86 when turning the key. The power coming from the ignition switch needs to be tested on all output leads to be 100% positive it is correctly installed
Click to expand...
@coolasice...I am still at work and will do what I can to troubleshoot that IGN switch in the dark and cold. I will also double check PIN 29 on C1 with key in run and crank. Will also pull Fuse 22 to see if voltage drops out when key is pushed to start. Will check for HOT on 68 with truck in gear. Do you think it possible that the neutral safety switch is letting voltage through in Run but not in Start?
 
Rad said:
@coolasice...I am still at work and will do what I can to troubleshoot that IGN switch in the dark and cold. I will also double check PIN 29 on C1 with key in run and crank. Will also pull Fuse 22 to see if voltage drops out when key is pushed to start. Will check for HOT on 68 with truck in gear. Do you think it possible that the neutral safety switch is letting voltage through in Run but not in Start?
Click to expand...
Very much doubt that it would be the safety switch
 
coolasice said:
Very much doubt that it would be the safety switch
Click to expand...
Since it's so damn cold out tonight, I only did a quick check on socket 68 with shifter in neutral with key in run (68 Hot) and with shifter in drive (68 cold). Backup lights illuminate with shifter in Reverse. It's definitely not the neutral safety switch. Will probe the ignition switch wires again in all key positions - just not tonight (just got home - worked late). Didn't get another switch yet but will. Thanks!!
 
FWIW. I bought my 03 TB new, and the dealer made
a extra key at my request. They told me that only GM
dealer or locksmith could make a ignition key for it.

Edit: because of the security system.
 
Texan said:
FWIW. I bought my 03 TB new, and the dealer made
a extra key at my request. They told me that only GM
dealer or locksmith could make a ignition key for it.

Edit: because of the security system.
Click to expand...

I was leaning on that also but he said they have been using a key from Lowe's.

He hasn't stated yet if he tried another key.

Op.....Didn't you scrounge around yet around the steering wheel or above the passenger panels yet for any aftermarket components?

After you said that things are different with both ignition switches it still could be a faulty switch....but also..have you checked your trans harness yet for fluid contamination?
 
Sorry guys...had to run out of town for a day to my second home. Boiler crapped out which required immediate attention with temps in the teens at night. Over the past 3 days I really haven't had an opportunity to do anything with the truck short of a quick check on Starter relay socket 68 for juice with shifter in the different positions. Ruling out the neutral safety switch. I do REALLY appreciate everyone's input. Between work, the temperatures, and my upcoming military duty obligation this coming weekend, it doesn't look very promising that I will have a lot of time to check the things you want me to check.

As @coolasice suggested, I will check the pink wire at the switch for power with key in crank *(as well as the remaining wires since I had the ignition switch out again recently). While the lower panel is off, I will take another real good look under there for anything resembling add on things (alarm/remote start). I won't be able to check for fluid contamination unless I keep the truck running again after jumping across the starter relay pins and driving it up on ramps. Hopefully that won't be necessary.

I will report back - hopefully with better news!

EDIT: Yes, the wife has been driving the truck without issues with the Lowes cut key for at least a year. I still have her factory key and will try it. The eyelet broke on it so she went to Lowes and had one cut.
 
Texan said:
FWIW. I bought my 03 TB new, and the dealer made
a extra key at my request. They told me that only GM
dealer or locksmith could make a ignition key for it.

Edit: because of the security system.
Click to expand...
Dealer lied... key can be made anywhere... nothing special in these keys

"The ignition lock cylinder fits inside the ignition lock cylinder case and operates the ignition switch when turned by a key with the proper mechanical cut. When the ignition key is used to turn the ignition lock cylinder to crank, start, a magnet on the lock cylinder passes close to the Passlock™ sensor within the ignition lock cylinder case. The magnet activates the security hall effect sensor in the Passlock™ sensor which completes a circuit from the security sensor signal circuit through a resistor to the security sensor low reference circuit. The resistance value will vary from vehicle to vehicle."
 
Lied or was just plain dumb because most other GM vehicles use PK3 keys with chips.
 
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coolasice said:
I would go back to the ignition switch and test the pink wire out of it, should be hot in run and start...
Click to expand...
@coolasice - you are the MAN! It was a little warmer out today so right after work I went to probe the pink wire with my test light coming out of the ignition switch and it went from HOT in Run to cold in Crank. So I pulled the switch back out (did this a few times) and moved the little gear on the switch a tooth at a time (I'd say no more than 3 teeth until the switch didn't feel right anymore when turning the key) and the power kept dropping out in the start position. Then I took the original switch and worked the hell out of the little gear wheel and put it back in and tried it. Low and behold...the truck fired right up! Of course that was short lived because when I shut it off and tried starting it again, the speedometer and RPM gauges were right back to jumping all over the place.

This convinced me that the new switch was bad. I went to Advance Auto Parts, bought another new switch, put it in, truck fired right up - and does so now every time! You guys were saying all along that it sounds like a bad ignition switch. After spending $56.00 with tax on an OEM switch, who would think that the dealer sold you a faulty, defective switch? I had a hard time getting past that. Wife is paying the dealer a visit tomorrow with switch and receipt in hand. We'll see how that goes!

That being said and problem solved, I want to thank each and everyone of you guys who helped me with this damn problem. If nothing else came out of this, I became very intimately familiar with the TB's electrical system.

Again, thank you to all of you for sticking with me and supporting me through all of this. I know the easy thing to do would have been to take the truck to the dealer, but I just don't like anyone touching my s..t! I feel like I made some friends on here and view all of you as such! You all are the BEST!
 
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You are most welcome.
I changed the title to SOLVED! This has to be the longest ignition switch thread!
 
Glad you got it worked out. I would have done the same thing you did on the switch and figured the new one couldn't be bad out of the box probably.
 
Glad you got it figured out! This thread was great to follow, it was my go to thread every time I logged on.
Awesome ending, nice work GMTNation
 
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