2003 tahoe no crank no start

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OR VietVet

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And I have a code reader that plugs in and a Bluetooth one and neither of them will read.
Where did you check the fuses/relays? There is an ECM fuse, 15 amp, in the fuse/relay box under the hood. Several Ignition fuses as well in there and the fuse side box at end of dash. I think your ECM is in the same place as mine. Next to the battery. Check all the wires there for any rodent damage and connections. Is easy to unplug. Sometimes, just unplugging it and plugging back in, is enough for it to clean the connections.
 

rockola1971

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While trying to crank engine, have someone grab starter solenoid to see if they can feel if the earlier click you heard is coming from the starter solenoid. If it is then you likely have a bad ground or hot connection and need to fix that. Your code readers will not connect to the PCM if the PCM and the code reader arent getting the correct 12v+ and ground from the battery and the code reader gets that through OBDII connector under the dash which is powered by the battery via ground and a 12v+ connection as well.

Basically a bad connection at the battery(+ or -) or your ground connection from the battery to the chassis ground or the positive connection that ultimately goes to the fuse box, all will cause the symptoms you are experiencing. They all need verified clean and tight. Battery also needs verified as good and fully charged. You need a voltmeter and someone that knows how to use it.
 

NickTransmissions

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I have 2003 tahoe, was running fine and next day wouldn't start. Accessories, dash lights up, but when turn to start and nothing. No click nothing, it's like when you turn on all power is cut off. You can't even tell that you turn the key to the on position. Checked starter, battery, fuses, relays, changed ignition switch, tested neutral safety switch,tried all the tricks found on the internet with the key and gear shift. I'm desperate and need help.
Are you still having this problem?

If so try starting it in neutral if you havent already done so.

If it starts in neutral but not park its your manual lever position sensor (MLPS). Its located on the driver side of the transmission at the selector shaft. Starting in neutral but not park simply indicates the "park" channel is dead but the "neutral channel" is still sending data to the pcm. If no crank/start in either park or neutral and all other suggested tests "/steps fail to yield any results, replace the MLPS.

ETA: Here's a video w/more info that I did on that thing about two years ago...
 
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SnowDrifter

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Lets isolate and chop the system in half.

Grab a multi meter, and lets look at the starter relay.


1. See if the signal gets power when you turn the key. I don't remember if it's switched power, or switched ground. Will be easy to check. Switched power = 0v on pin 86, energizes when start. Pin 85 will always have continuity to ground. Switched ground = always 12v on pin 86, open-circuit to ground unless start command. You'll also want to validate that pin 30 has power. This should be always 12v.

If all things there check out, issue is downstream. Check starter, solenoid, wiring, grounds, etc. And I mean check it. Don't load up the parts cannon quite yet.


If it's not receiving signal to switch, 3 things I'd look at next.

2. Check passlock / key / whatever the thing GM uses is. Can get more info later if ya can't find on google.

3. Check P/N lockout. Seen pinouts there, and on ignition switch

4. Check the ignition switch itself. Need to pull the steering column plastic off and start probing pinouts.


Between all of those, should be able to start to hone in on what's sad


Also, for the OBD not reading - it's a shared fuse with one of the interior 12v outlets. Don't remember which one.... But sanity check those are good
 

NickTransmissions

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Also, for the OBD not reading - it's a shared fuse with one of the interior 12v outlets. Don't remember which one.... But sanity check those are good
@smoore

Replace the 15amp fuse for the driver side cigarette lighter. Fuse is in with the others in the engine bay.
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bladenbullet

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Voltage drop your battery cables...these are notorious for micro corrosion where the cable ends are swaged onto the cables at the battery...a simple fix is sweating solder into the cable ends...you might try wiggling the cables at the swages while trying to crank...the light loads on the cables won't bother it...the heavy load of going to crank severs the connection and the vehicle gies dead...if you disable fuse and get it to crank you'll find a 1.5-4 volt drop at the cables...that's enough to look into sweating a repair...had the identical concern on my own 7 years ago...haven't had a problem since sweating them in...did a similar repair on my captiva with the same issue...3 years without a symptom...
 
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Jeff O

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Had similar problem on my 2003. Was traced to corroded pins on bottom connector of main computer located on left side of engine. Not protected that well from contaimination from water, spray, and here in NE US salt.
 
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