2005 Grand hard start and random shut off while driving

[Lor411]

Hello, I have a 2005 Grand AM SE v6, 3.4 that I had purchased used in 2008 with less than 23,000 miles. It is now at 52,000 miles. My troubles started less than a year after I bought it. In the last 4 years I have viewed just about every forum on the issues I am having, but I have not come across any with the same issues, there is usually a slight difference. Here are the details.

Car has hard starting problems randomly. Engine always turns over but does not always fire. Sometimes it starts right up, other times it takes several attempts. Totally random.

Car randomly shuts off while driving. Just cuts power, no warning..no sounds. No specific speed, totally random.

When starting, with the key in the "on" position, if the "service engine" light DOES come on..the car will start 100 percent of the time. If the "service engine" light does NOT come on, the car WILL NOT start 100% of the time. This is totally random also, but the car will ALWAYS eventually start.

Once the car starts, it runs fine..sometimes it shuts off , sometimes it doesn't.

I've had the fuel pump pressure checked ( right up to specs). Replaced the Ignition Module (no help).
Replaced the Fuel pump Relay ( no help).

No codes come up at all. Both my mechanic and a friend of mine ( and my own observations from reading forums) lead us to believe it is a PCM issue..but another thought I have is possibly the connections (fusible links?)

Is it possible for me to take the PCM to have it tested and would a local mechanic be able to so that or will I have to contact a GM guy?

Any suggestions or observations would be greatly appreciated!

[thephantom1492]

What about the key ignition switch?
You have a few switches in it.

I had issue with mine, and couln't beleive it was that until I did some voltage mesurement...

In my case, the main issue was: turning on the hvac blower from off to 1-4 caused it to not turn on right away, then turn on. From 5 to 1-4 it was even weirder: the blower was turning off, then after 1-10 seconds it was turning back on. Once the service vehicle soon light turned on, but no code got stored. The issue was that one of the 2 ignition contacts was spotted, causing a bad contact. I ended up cleaning the contacts since I was short on budjet and had to order the part, so like a 2 weeks delay... The cleaning worked.

Your car ignition switch actually contain 5 switches.
- Ignition switch batt 2 fuse (hood)
- Switch 1: hot in run and start
- Ignition module
- PCM
- Injectors
- BCM
- Transmission
- ABS
- airbag
- hazard Switch
- Switch 2: hot in acc. and run
- wipers
- turn signal
- Igition switch batt 1 fuse (hood)
- Switch 3: Hot in run
- HVAC control assembly
- Evap vent + purge solenoids
- Oxygen sensors 1 and 2
- Sunroof
- BCM
- Cruise control
- Electric windows
- Switch 4: Hot in run, acc. and start
- PCM
- Instrument panel
- BCM
- Switch 5: Hot in start
- PCM
- Starter (via the transmission shift interlock switch)

Of course, this list is incomplete, and contain possibly some options that you don't have (ex: sunroof) and also some computers are on multiple fuses.

My guess would be the switch 1 that make bad contacts, which would explain your issues quite well...
With a voltmeter you could maybe be able to diagnose it: Turn the key as to show the issue, then try to check the voltage at various fuses, like the injectors fuse... chance is that you find that some of them is too low while in trouble, but ok when the trouble is not present. Chance is that the multiple fuses that show the same voltage is in the same group...

As for cleaning it up if it happend to be the proven issue: be aware that it is technically not a servicable part, that you have to dissassemble the switch that might have several tiny springs and pins. For cleaning, a VERY fine sand paper (like 400+) is needed, I used I think some 1000... be ready to replace the part (expensive) if you lose a single spring or pin, or break a tab, or whatever happend... And could not work well if you sand it at an angle or something... For this reason I suggest to just replace it.

[Lor411]

Thank you so much for all the great info! Unfortunately, I have a only a very basic amount of knowledge about cars...but a couple of months ago I did buy an new ignition switch but did not have it installed thinking it may not be the problem or perhaps only part of the problem...The thing is wouldn't the switch have died by now? 4 years later? It would be much easier if it just stopped running..!!

About the switch, What I bought was the ignition switch that goes inside the lock cylinder. How do I know it is not the connections to the switch itself? Forgive me if I sound like an idiot..But I am!! Would the ignition switch also cause my car to shut off? if that is the case, I can have my mechanic replace it for me since I already have the part..what do you think? Thank you again, you've been very helpful.

Laura

[thephantom1492]

If the harness is discoloured, melted, some wires are harder than the others, or show some other weird sign of heat (a bad contact cause heat due to increased resistance), or is loose, then it might be it. Also, look at the pin color... Blueish/black is a sign of heat.

As to why now and not before, contacts are a bit complex... I mean, the metal have to touch enought, if the contact do not it heat up can burn some oxide or melt some metal, or disform the shape of the contact, causing a new contact area... also, an electric arc can spot, pierce throught the oxide layer, melt and alike the contacts...

And yes, it does go behind the ignition key... and can be a pita to get to. On my car I had to remove the plastic around the steering, then the bezel around the instrument cluster, remove the instrument cluster, remove the kick panel under the cluster (the panel on top of the pedals), the central consol bezel and finally the radio... All that for 3 bolts, 1 pin and 2 connectors...

But the issue I have is gone now, yay!

[Lor411]

Originally Posted by thephantom1492

If the harness is discoloured, melted, some wires are harder than the others, or show some other weird sign of heat (a bad contact cause heat due to increased resistance), or is loose, then it might be it. Also, look at the pin color... Blueish/black is a sign of heat.

As to why now and not before, contacts are a bit complex... I mean, the metal have to touch enought, if the contact do not it heat up can burn some oxide or melt some metal, or disform the shape of the contact, causing a new contact area... also, an electric arc can spot, pierce throught the oxide layer, melt and alike the contacts...

And yes, it does go behind the ignition key... and can be a pita to get to. On my car I had to remove the plastic around the steering, then the bezel around the instrument cluster, remove the instrument cluster, remove the kick panel under the cluster (the panel on top of the pedals), the central consol bezel and finally the radio... All that for 3 bolts, 1 pin and 2 connectors...

But the issue I have is gone now, yay!

Ok, my ignition is located on the dash. The harness was separate from just the switch itself (which I did not buy). Do you think it's worth the try to check the contacts and install the switch if all looks good? There is nothing to lose here. I suppose if the same problems occur after the switch is installed, I will bring it to my mechanic to check the harness. That's all I can afford to do right now anyway...At this point, I really don't want to drive it anymore...got stuck way too many times in the middle of traffic...not good! Thanks again!

[thephantom1492]

same as mine, on the dash, between the steering and the radio...

if you already have the switch, I'ld just replace it... I wouln't take the time to open and try to clean it up...

it's not that complicated, just a pain to get to it...

Here is the problem: from the kick panel, there is not enought space to slide it out... The radio... cover part of it and no room to take it out (you probably don't need to remove the radio I think)... so really, the way to take it out is by the instrument cluster... which is the pita...

[danielsatur]

Did you rule out the battery?

[Lor411]

Im sure connecting it is much easier than getting to it. How long do you think it would take for a mechanic to do it? It might be worth it for me. I can take apart and fix computers, but as for cars...I had a hard time getting the fuse panel off!!

[Lor411]

Yes, we have pretty much ruled out the battery. My mechanic checked the connections to the battery as well. He also cleaned the fuel lines, checked the fuel pressure. He actually never got the car NOT to start. Until this past March. He told me he tapped the fuel tank and the car started..So he was convinced it was the fuel pump....Until I told him about the car not starting if the Service Engine light does not appear when I turn the key (pump doesn't prime either if the light is not on)..He thinks is the PCM and so does a friend of mine who works for Toyota. But I had already bought this ignition switch and I suppose I should try that before getting into the computer issue.

Thanks for your help!

[thephantom1492]

it's not that complicated, a mechanics might charge maybe 2 hours... which mean it took him 1 hour...

[Lor411]

I would gladly do it myself if I was sure I could put the dash back together!! I could not find any instructions on line for the 2005...but Im still looking.

[thephantom1492]

I have the procedure, I'll type it out later in detail...

basically, disconnect battery negative. Remove the instrument cluster, which should be: remove the 2 screws under the steering, remove the top cover, burried behind you have 2 screws for the IC trim, plus 2 on the top, remove trim. remove the screws for the IC, remove IC by noticing how you remove it (it slide in/out one way, easy to figure at removal, harder at insertion time). Remove ignition switch, relocate to an easier to access, put key to run, press and hold the button under it (metal tab/pin), pull the key... the rest should be easy...

will write more in detail later today

[danielsatur]

[quote=Lor411;7001166]
Car has hard starting problems randomly. Engine always turns over but does not always fire. Sometimes it starts right up, other times it takes several attempts. Totally random.

Is she getting a spark + fuel during this Time?
Doe's this only happen when she's random Hot?
How about the Ignition control module?

If you suspect the ICM when hot, you can use electronic freeze spray to cool it down.

Symptoms of a cold/ hard start could also point to a bad MAP/IAT sensors, they are both used by the ECU/PCU to formulate the Air/fuel mix..

[Lor411]

Hi Daniel,
Thank you for your help. The very first thing I had done was have the fuel system checked, lines cleaned, filters, pressure checked and fuel pump relay replaced. 2nd thing I had done was replaced the Ignition module.

There were no codes at all from both mechanics that looked at it.
Also, it does not matter whether the car or the weather is cold or hot, whether its raining or sunny. I have been listening and observing the car for 4 years.

I was told that a fuel pump going bad would not cause the Service Engine Light issue I am having - where the light does not come on when I turn the key, the fuel pump does not prime and the car will not start.

Would any codes show up if the Map sensor was bad? Nothing has showed up at all..no code...nothing. Which leads me to believe its an electrical issue.

Even when the problem occurred to both mechanics there where no codes showing up.

Since I already purchased the Ignition switch (a few months ago) I suppose it wouldn't hurt to replace the old one and see what happens. Thanks again!

[Lor411]

Thank you for the instructions! I will let you know the results as soon as I can get to it (or chicken out and bring it to a mechanic) I appreciate all your help (both of you)!