NEED HELP 2005 Trail Blazer LS, 4.2 Engine No crank Weird Problem

[jrbaldwin]

2005 Trail Blazer LS, 4.2 Engine, Auto Transmission.

Fall 2017 the Trail Blazer would not crank or start. Would not start when jumped fuse box relay. Starter tested bad. Replaced with NAPA Starter. Started properly again.

Spring 2018 the Trail Blazer starting having problems again. Would not start when jumped fuse box relay. Starter tested bad. Replaced with more expensive Rock Auto Starter. Started properly again.

Summer 2018 the Trail Blazer had occasional starting problems that slowly go worse. Changed the ignition switch and started properly again.

Starting problems started again and getting worse till wont start.

Ran the following tests
Battery 1 year old and tested good
Battery connections clean and tight
Fuse box red power wires clean and tight
No security light on
Park Neutral Switch operates normally

Fuse Box
10 Amp Fuse 17 test good with 12 volts each side
40 Amp Fuse 34 test good with 12 volts each side

Starter relay
12 volts on starter relay 86 & 87
When jump 12 volts from battery or starter relays 86 / 87 to 30 engine starts great
Used test light connected to battery + to started relay 85 and lights comes on when turn key to crank. So PCM getting start signal and going to ground.

Removed starter relay plastic top and starts great when manually activate relay.

Ignition Switch
Have power to red wire.
On crank have power to yellow wire
Replaced ignition switch with new switch and no help.
Took old ignition switch apart and looks good inside

Open the rear fuse box and 12V at the large connector with the red wire on it. Checked and it's tight

Currently when try to start dash lights dim. Hear click in engine compartment. Some times dash lights do not come back on and key is stuck in ignition like lose of power. More and more dash lights do not come back on and key is stuck. Here is the strange part when I get up off the drivers set the dash light come back on and I can remove the key till I try to start again. Seem to be associated with left side of drivers seat. When try to start and dash lights go out can press down on left side of drivers seat and dash light come back on.

Disconnected seat switches and wiring plugs that I can reach. No help. Looked at the wiring diagram and do not see a drivers seat ignition interlock safety switch that can be going bad.

Any ideas? looking at pulling drivers seat next.

Jim

 

[S13Hitman]

https://gmtnation.com/forums/threads/stalling-and-rpm-jumping.19093/

Go to post #26 and watch the 3rd video. I would link it but I'm at work and can't do so. This guy shows a major grounding point behind the dashboard that is easily accessible with a screw driver. Your weird issues made me think of that grounding point. There's a ton of things be grounding at that 1 spot.

Hope that helps you...

 

[jrbaldwin]

Thanks. Was thinking a grounding issue or a shorting issue under the seat. Unplugged everything under the seat and did a parasitic draw test to start checking for a big draw. Started at 1.5 amps when connected the meter but after a minute dropped to milliamps. Was being to rain so went to start by manually activating the starting relay to move inside to keep working out of the rain. Could hear the starter solenoid engage but no starter. Then after a couple of seconds I could hear the solenoid disengage. Sounded like a dead battery. Was full charge 2 days before. Tested the voltage and battery SG and showed 75% charge. Put the battery charge on the battery and set to starting setting and would not start. Let it charge for 10 minutes and started from the relay but not the switch. But with only a milliamp draw and losing 25% charge decided to take the battery into the auto parts store to be tested. They put a digital battery tester on it and voltage showed good but the tester showed the battery at 29%. Said the 9 month old was bad. Something wrong inside the battery. Found the original receipt and received a new battery. Last night installed the new battery and car started from the relay. Then tried the switch and started. The battery must have been just bad enough to be able to start from the relay but not from the switch with the extra draw of the accessories. The auto parts store is a 18 mile trip each way. Last time I am getting anything electrical from them. The rebuilt starter only lasted 3-4 months. Took the car for a long drive today and ran good. Check for codes with my scanner and no codes. Still don't know why pushing on the left side of the drivers seat made the dash lights come back on.

 

[S13Hitman]

I've been learning over the past year that 1 thing wrong with the electrical means 4 other things act up or throw codes, or other weird things.

My ABS light comes on and then my truck stalls. How the heck does that make any sense.

 

[Mooseman]

Search on YouTube for a video by May03LT for this. He shows the full circuit that has to work to send the start signal. I'd link it but I'm at work.

 

[jrbaldwin]

Thanks watched several videos on the starter circuit and how to test. Downloaded the circuit diagram. Everything a big help but did not cure the problem which finally turned out to be a new battery with internal issues. Replace and all the problems went away. Jim

 

[EPfiffner]

Thanks watched several videos on the starter circuit and how to test. Downloaded the circuit diagram. Everything a big help but did not cure the problem which finally turned out to be a new battery with internal issues. Replace and all the problems went away. Jim

Crazy, a bad 9 month old battery, and then a bad new replacement! That's frustrating. Glad you figured it out.