2005 Chevy Duramax won't crank

swap the relay with another in the box and see if the relay is the problem.

already tried that with no success.

"but the starter relay is not getting voltage to the solenoid wire." - Is there voltage present to fire the starter relay? Can you swap with another relay to see if the relay is good?

Is there voltage to the coil side of the relay?

The starter relay has 4 pins on it. One is constant 12v. The other 3 show ground. You can take a power probe to one pin (the one that is the wire going to the small wire on the actual starter solenoid) and the truck will crank. I have swapped the relays, but still has the same results

it's the Ground....It's always the ground...black cable off of battery's connections to frame/chassis is unable to pull the 300 CCA necessary to do the job, also the 1/0 cable going to your motorblock is necessary for to power up the startermotor and solenoid~...check the bolt on the positive side too what connects the cable to the solenoid too~

bad ground is like bad hooch...barely does the job....with complications~

It starts when you shoot start signal to it judge

Clarity of thought...clarity of power connections---

What grounds the relay? The pcm?

If it were a bad ground wouldn't it still not start when 12v is shot to the relay wire? May be wrong...Just asking. I also hooked a set of jumper cables from the ground side of the battery to the starter housing itself with same result

I am getting juice to the starter fuse with the key...but not the starter relay.

Yea it has power but ia power going through it? Something has to turn the relay on. Its not on all the time or else the truck would crank all the time

my thinking is the PRNDL switch not giving signal that the truck is in park. I have replaced it before, but when it messed up the last time the information center on the dash had a "range selector switch out of range" and now it does not. However, the tow/haul button is not working

No it is not going through it. I checked the wire on the bottom side and it is only getting voltage to the one (12v constant) wire

the amount of cold cranking amps is insufficient~ the other end of the black cable must be comfortable with three hundred amps!...this and the motorblock connection too----sounds like a wimpy sister is going in to do a MAN's job~

Its gonna need more than 300cca to crank a diesel judge. The problem here is its not gettin a start signal cca is irrelevant in this case.

....the starter switch....incredible~

contacts that are out on lunchbreak, when they show up are drunk...sounds like to me~

BoonStewart, I have an identical problem with my 2005 Duramax. What did you find was the problem?? Sure would appreciate some feedback. Thanks. Glen

My 203 3500 Chevy Duramax engine will not turn over it was working fine then on morning it's not. I have replace both batteries and put a new starter and new starter relay all fuses are good but it still will not turn over. Has any one had the problem and if so what was the fix?

starter needs 24 volts to turn

Transmission mogul will keep the engine from cranking over. Just replaced mine.

The ignition switch malfuntions and triggers a security problem and will sometimes blow fuses and then reset security and they will start. It stops signal to starter

Connect a wire to one of the pegs of the transmission control module TCM (its that square thing on the back of the radiator top driver's side, that has all the aluminum pegs on it) and the other end of the wire, to a ground source. Try cranking the motor. If it does, the TCM has been damaged by coming into contact with 12 volts. Some other symptoms of a bad TCM are the dash does not display PRNDL transmission positions and often a brake trouble light will appear.

Mine just started the same thing and my prndl don't show up on the dash

My 05 duramax isn't starting when I turn the key over it immediately blows a 40 amp fuse. Then my service 4wd light comes on. Iv waited a while and put another one in it and it would start go a couple days then blow it again... Help please!?

I had this problem, engine would not crank and blowing the 40 amp fuse. Solution for me was the purple start wire to the solenoid had burned and shorted to the exhaust manifold near the power steering pump. I removed harness from the starter back until I got to the bad spot and repaired and rerouted the wire so it would not burn again. Remove wheel and wheelwe'll to get to starter. 2008 duramax

I have an 05 duramax lly. went to start it and nothing tryed jumping and charging batterys and i got it to crank a few times then nothing again. changed batteries still nothing, changed relay checked fuses nothing still. when the key is turned dash lights flicker and bounse and i get some clicks or nothing as if i have dead batteries. i jumped the relay and can hear my starter spin without engauging and turning over motor. could this all be caused by just a bad starter? Anyone have any thought? would appreciate any thanks.

So after trouble shooting the ignition by sending power (12v) through the crank fuse and turning the key, found that all wiring is good. Would have to be one of the ignition fuses. Checked all fuses with test light and found 40amp ignition fuse to be bad. Replaced and attempted to start. All working as it should at this time.

Try grounding the transmission control module on radiator fan shroud outside aluminium pegs to ground. When the starter relay is not energized from the ecm yellow/blk wire. The ground to transmission module worked for me. And it is a easy simple test. Thanks jmac2737 .

I have the same thing going on change the relay stared working then week later back to the same thing but now my turn Indicators stopped working as well

i realize this is an old thread however im having an issue with 1 sec cranking however if i unplug the crank shaft sensor it cranks all day checked and cleaned all grounds. the only thing i cant remember is when i tore the top down to do injectors and cp3 pump is if there was a ground on the rear of the right head or not. this is a 2007 LB7

2007.5 no crank or start. Good batteries and fuses. No power to the starter on small wire.

I have a 2006 lbz kinda in the same boat. I can hot wire it at the ignition relay. And jump the starter. But when I do the trucks stuck in 3rd gear. The orange light for gear select is out and the speedo reads 0