Intermittent Start - SOLVED

[SnowBuck]

Turn the key on. Dash lights come on. Turn to Start = nothing (no crank)! Try 5 or 6 times and maybe it'll start. Runs fine after that...but it's a crapshoot if it'll start again. May go weeks before this happens again.
Replaced: battery, Engine Control Module (programmed by Dealer), Starter Relay.

 

[strutaeng]

Next time it happens go down there with a test light and see if you are getting power to the starter solenoid when you flip the key to crank.

A long test lead and putting the test light on your windshield is an option if you don't have a helper.

 

[Doubeleive]

carry a hammer with you, next time it happens reach under there and smack the starter a couple times, if that works then replace the starter.

 

[rockola1971]

Could be alot of things. Bad starter, corroded or loose battery cable at either end, bad ignition switch, bad or misadjusted safety switch at tranny (Park. neutral switch). Bad ground at the firewall or engine block, this guy can cause havoc on your BCM which just so happens to give the PCM the OK to start engine AFTER your passlock system tells the BCM you aint a thief.

 

[OR VietVet]

Last time I ran in to these symptoms was a failing ignition switch in my girls TrailBlazer, same switch by the way, and now no problems but as has been said, it could be numerous components.

 

[SnowBuck]

Next time it happens go down there with a test light and see if you are getting power to the starter solenoid when you flip the key to crank.

A long test lead and putting the test light on your windshield is an option if you don't have a helper.

No power to the starter, that's why I replaced the ECM and starter relay. Still intermittent start.

 

[OR VietVet]

An updated ignition switch will have the grey covers mixed with black, instead of all black. Very hard to find a genuine GM part but are out there. I found one at ebay. It is a less than 30 minute swap out and there are some videos at you tube. I have a couple videos there showing me replacing that switch on my girls Trail Blazer. Is basically the same steps. Not very expensive and was definitely the source of her intermittent no crank problems. The updated switch is because of internal contact problems causing the intermittent no crank problems.

 

[Doubeleive]

No power to the starter, that's why I replaced the ECM and starter relay. Still intermittent start.

you did not state this in your initial post, details like that are critical to diagnosing the problem
this means you probably need to trace the problem from the ignition, replacing the ignition is cheap and easy, then if it still happens it is one less thing to check
the most common issue's are
**grounds**
starter solenoid
starter power cable/harness
ignition switch
ecm harness (corrosion/water intrusion)
then it gets harder, like broken wire in firewall, bcm harnes, etc
or like already stated something simple like a transmission position sensor, shift interlink etc (scanner would be helpfull)
if you have a tech2 or comparable high end scanner it can tell you the ignition position when the problem occurs, with the scanner on and switching the ignition positions it will tell you if it is working, if it is then you know the problem resides somewhere else or if it does not show the correct position then you know it is from ignition to bcm
I think having the ecm reprogammed was probably a waste of money as that would be a last resort
intermittent problems are simply a pain......

 

[Fless]

By "no power to the starter" do you mean that the control circuit to the starter solenoid was missing the crank signal, or did you mean something else?

Starter solenoids can be intermittent.

 

[OR VietVet]

you did not state this in your initial post, details like that are critical to diagnosing the problem
this means you probably need to trace the problem from the ignition, replacing the ignition is cheap and easy, then if it still happens it is one less thing to check
the most common issue's are
**grounds**
starter solenoid
starter power cable/harness
ignition switch
ecm harness (corrosion/water intrusion)
then it gets harder, like broken wire in firewall, bcm harnes, etc
or like already stated something simple like a transmission position sensor, shift interlink etc (scanner would be helpfull)
if you have a tech2 or comparable high end scanner it can tell you the ignition position when the problem occurs, with the scanner on and switching the ignition positions it will tell you if it is working, if it is then you know the problem resides somewhere else or if it does not show the correct position then you know it is from ignition to bcm
I think having the ecm reprogammed was probably a waste of money as that would be a last resort
intermittent problems are simply a pain......

It is like pulling teeth sometimes, getting info.

 

[SnowBuck]

Could be alot of things. Bad starter, corroded or loose battery cable at either end, bad ignition switch, bad or misadjusted safety switch at tranny (Park. neutral switch). Bad ground at the firewall or engine block, this guy can cause havoc on your BCM which just so happens to give the PCM the OK to start engine AFTER your passlock system tells the BCM you aint a thief.

I think you mean the ECM (Engine Control Module) ? Replaced it. Passlock system wouldn't let it start til I had the Dealer program it. Worked fine for a month, then back to intermittent start.

 

[SnowBuck]

By "no power to the starter" do you mean that the control circuit to the starter solenoid was missing the crank signal, or did you mean something else?

Starter solenoids can be intermittent.

Replaced the Starter solenoid.

 

[rockola1971]

I think you mean the ECM (Engine Control Module) ? Replaced it. Passlock system wouldn't let it start til I had the Dealer program it. Worked fine for a month, then back to intermittent start.

Uhh no, not in a 2000-2006. Its called a PCM (Powertrain Control Module) which controls the engine AND the transmission. And the BCM (Body Control Module) handles mostly interior lights, passlock and what not.

 

[Doubeleive]

sounds like a electrical problem, if it worked fine a month after unplugging/plugging wires/battery/etc then I would disconnect those wires again and clean up the contacts and try again. even if the look ok, clean them anyway.

 

[afpj]

As others have said, bidirectional scan tool would be quite helpful here. IIRC, cam position sensor could cause similar symptoms?

 

[SnowBuck]

Nothing worse then "intermittent" problems. My final solution = install a Remote Start button under the dash !!!!

 

[rockola1971]

First thing id be looking at is the security light on the cluster. What is it doing?

 

[lyncht1967]

as a test connect one end of a black jumper cable to batt negative and other end of black jumper cable to block somewhere and try cranking...if it starts you have a bad negative battery cable..common on these models. can do the same thing from batt pos to starter pos and try cranking..if it starts you have a bad positive battery cable. common issues on these models...i had the same issue a month ago and it was bad negative batt cable.

 

[SnowBuck]

GOT IT ! But - what IS IT ?!?!? While installing a new ignition switch, found this. When holding in Start and nothing...hitting this caused it to start. Looks like some sorta starter interrupt. Taking it out = full start! Has "6900A" on it.

 

[lyncht1967]

Ahhh...yes...there's a variable isn't it. Looks like maybe an aftermarket remote start or alarm unit. Must not have been letting an ignition signal through. Great that it is out and now you're starting and running!