removal and adjustment ParkNeutralPosition safety switch

greggraves

Original poster
Member
Mar 30, 2014
28
2006 TB LS 5.3L. I am "pretty sure" that my intermittent no-start condition is due to or related to the PNP safety switch. Symptoms: normally there are no symptoms and the TB starts fine, but say on the 80th start 50 miles down a dirt road next to nowhere, when the key is rotated to ON the dashlights come on, then dashlights go out when turned to START position, no sounds, no clicks, no nothing, then :crazy:dashlights come back on when the key is returned to the ON position. This is the same thing I experience if I try to start the vehicle in R or D. Battery is new, cables tight, wires to solenoid and starter tight. That is why I am thinking the PNP switch. No codes are stored. So before I go and break something, or wind up not being able to get the new switch back on or adjusted, does anyone have the info to do this properly? I've surfed about various places, incl. Youtube, but I don't get a whole bunch of confidence doing this without asking someone KNOWLEDGEABLE or finding a GM manual or whatever that tells me how to DO CORRECTLY.

PS: I live in Florida and we are going to be towing a 5000 travel trailer to Colorado and beyond, so would prefer to avoid getting stranded.

PSS: This vehicle has been driven to 2 different shops, towed to another, and sure enough starts up fine and "can't be fixed 'cause it ain't broke". Arghhhh.

PSSS: I am going to replace the starter relay as well just because it is $11 and replacement requires skill and intelligence of orangutan which I believe I can muster.

Thanks.
 

IllogicTC

Member
Dec 30, 2013
3,452
Welcome!

A rather common issue with no-start scenarios seems to be the ignition switch. Have you checked and ruled out this possibility yet? It may be something as simple as the contact for START within the switch isn't quite getting hit when turning the key. Threads on replacement if this is deemed your culprit are literally all over the place around here, that's how common it is.

For testing the PNP switch, locate it first on the lower-left side of the transmission. Pin 12 should be a pink wire, that's feeding +12V whenever the vehicle is in RUN or START. Pin 1 is a yellow wire, and only has power when Pin 12 has power, and the switch is in PARK or NEUTRAL. This is part of the starting interlock.

I would imagine your best course of action to test the PNP would be to rig up a test bed and observe that Pin 1 has power when in Park or Neutral, and the key in RUN or START. If you have a scenario where it doesn't, then switch your testing over to Pin 12 and observe that it has power whenever the ignition is in RUN or START. If not, it's likely your ignition switch.

In the Technical Discussion area for the GMT360/370/305 platform, there is thread marked as a sticky toward the top of the list that reads "Need manuals? Get them here!" We have plenty of service manuals available in PDF format for free in this thread, just download the ones relevant to your year.
 

greggraves

Original poster
Member
Mar 30, 2014
28
Yes I understand the procedure, and in fact have the step by step GM diagnosis chart I downloaded off your site ... however, none of that does me any good when there is no problem, i.e., when there is no problem everything checks out fine, which is almost 100% of the time. I figure there are four things that are likely culprits: the starter relay ($11), the PNP switch ($48), the ignition switch ($45 plus dealing with the Antitheft), starter ($500 installed by shop). Bottom line is that I have to GUESS what is wrong and start replacing stuff. I know the PNP switch malfunction will reproduce what I am experiencing, are you saying that the ignition switch would reproduce the same thing?
 

IllogicTC

Member
Dec 30, 2013
3,452
greggraves said:
Yes I understand the procedure, and in fact have the step by step GM diagnosis chart I downloaded off your site ... however, none of that does me any good when there is no problem, i.e., when there is no problem everything checks out fine, which is almost 100% of the time. I figure there are four things that are likely culprits: the starter relay ($11), the PNP switch ($48), the ignition switch ($45 plus dealing with the Antitheft), starter ($500 installed by shop). Bottom line is that I have to GUESS what is wrong and start replacing stuff. I know the PNP switch malfunction will reproduce what I am experiencing, are you saying that the ignition switch would reproduce the same thing?

It may as it's part of the interlock, but I cannot absolutely confirm as my switch has thankfully lasted me this long. But with something with such an intermittent failure, it's either shotgun parts or leave a test bed semi-permanently attached in hopes that it will show up again. If you're down with tossing a new relay in just to be sure, I don't see what it'd hurt if the price is right.

When the key is turned to START and the vehicle decides to flip you the bird, do the gauges do their self-check (where they go down and come back up)?
 

RayVoy

Member
Nov 20, 2011
939
So we can break this down with a little thought........................

- if the relay was bad, the dash lights would not be impacted.
- ditto for the starter
- the ignition switch is a know failure item
- the PNR switch has not caused a reported (on this iste that I am aware of) failure.

I'd try the ignition switch first.
 

greggraves

Original poster
Member
Mar 30, 2014
28
Yes the gauges act normally when the random finger is flipped, just like they do when I try to start in R or D when everything is working OK. Apparently, replacing the key switch is "easy" job. Do you think replacing the PNP, the starter relay, and the ignition switch is good shotgun approach? Or would you replace one more likely than another given the symptoms I have stated above?
 

IllogicTC

Member
Dec 30, 2013
3,452
greggraves said:
Yes the gauges act normally when the random finger is flipped, just like they do when I try to start in R or D when everything is working OK. Apparently, replacing the key switch is "easy" job. Do you think replacing the PNP, the starter relay, and the ignition switch is good shotgun approach? Or would you replace one more likely than another given the symptoms I have stated above?

If everything else about turning to START EXCEPT the actual starting checks out, and there's no other odd electrical gremlins, you may be heading in the right direction with your PNP diagnosis. If you want to do all three, that's up to you but I would lean toward either PNP or ignition switch, and right now you have me leaning toward PNP (plus the relay because why not?).

I'm sure someone else will show up with questions or answers, too. I'll see if I can get one of them in here if you'd like to be certain before you go cracking your wallet open.
 

greggraves

Original poster
Member
Mar 30, 2014
28
I have found detailed info on trailvoy with pictures regarding the ignition switch change-o. However, the purpose of my post originally was to get hints on what to do, and more importantly not do, when screwing around with the PNP which is mounted to the transmission which I'd REALLY REALLY !!! not want to break/ruin/bust.

Another thing I just thought of is that changing the PNP requires tools and ramps and would be a helluva lot easier (if I was sure I knew how to do it) here in my driveway versus in a Walmart parking lot in the rain at night, no safety jacks, etc. However, changing out the ignition switch only requires getting that part at Autozone or wherever I am, and using minimal tools inside the car on the floor. That ---seems--- to also indicate doing the PNP first. What you think?

PS: no matter what part I do first, it will undoubtedly be the other part.
 

IllogicTC

Member
Dec 30, 2013
3,452
greggraves said:
That ---seems--- to also indicate doing the PNP first. What you think?

PS: no matter what part I do first, it will undoubtedly be the other part.

I'd go with the PNP, and then get an ignition switch. If the PNP fixes it, great! Then you have a spare ignition switch because it's only a matter of time before it takes a dump, too. That's if you're into keeping spares on hand of common-failure parts.

And isn't that the way it always goes, one fix either exposes or leads to another? :rotfl: That's what we get for wanting fuel efficiency, and more than 1HP per cu. in., and heated seats and all that lol. Just more crap to fix.
 

gpking

Member
Dec 27, 2013
534
Berkeley Springs, WV
My TB had the same symptoms, and as stated previously, the ignition switch was the culprit.

The previous owner got stranded once in 2005 and again in 2006, both times the ignition switch was replaced by the dealer under warranty.
Now, on the third ignition switch and second owner, the problem seems to have been corrected *knock on wood*. It seems like there should have been a voluntary recall here. $500 is outrageous for something that was probably faulty from the factory.
 

Texan

Member
Jan 14, 2014
622
I vote for doing the ignition switch first. If you do the transmission switch, be aware that
the shift cable connection to the shift lever ball is a plastic socket that gets fragile with
age and heat. I would not try to disconnect it, just remove the lever from the transmission
shaft.

PS: it is possible to replace that plastic socket, but I have only found the socket in the "Help"
section of the parts store, and you buy a assortment of 4 or 5 and choose the one that
fits.
 

RayVoy

Member
Nov 20, 2011
939
The cheapest and the easiest switch to change is the ignition switch. It has a know failure history and you have a number of members telling you that they had the same problem and changing the ignition switch fix their problem.

I think it is obvious that most of us think it is the ignition switch; however, if you still feel that it is the PNR switch, try moving the shift handle when this problem happens again. Rocking the shift handle will cause the shift lever to move the contact block and maybe complete a circuit if the PNR switch is intermittent.

But, do you want to wait until it happens again and then have the expense of a tow.

The best insurance, imo, is to change a switch that is a know failure waiting to happen and go on with your life :deadhorse:
 

greggraves

Original poster
Member
Mar 30, 2014
28
I am totally ok with changing out the ignition switch, if that is the problem, but you need to look at this from my perspective which is heading out on a 12,000 mile trip! If I could assure myself that screwing with the PNP switch was a waste of time, I wouldn't mess with it, as many of you have suggested. Beating a dead horse maybe so ... but a Google search for problems with PNP switches gets an awful lot of hits, kind of at a loss that there are none on GMTNation. Huh?

As far as the suggestion to rock the shifter about to try and make connection, you have to imagine me totally flipping out and trying to rock the whole damn car. If I related the ensuing profanity, I would be banned from this forum. Would you like to know what worked? Holy water. As the neighbors were calling the police, my wife sprinkled Holy Water on the car ... and it started. There ya go! That's what I should do ... take along a gallon of Pope juice!!

Please check my logic:

Assume my ignition switch is intermittent, that is what is bad, and it is now screwing up. I rotate the key and the contacts connect to ON and the dash lights turn on. I rotate the key to START, and because the ignition switch is faulty, the contacts do not connect and the signal to start the vehicle does not occur. I am thinking that in this situation NOTHING would happen, because rotating the key from ON to START isn't doing anything. If I am correct, then the dashlights do nothing as well. Bad ignition switch symptoms are dashlights come on and turning the key to start does not effect them, they stay on. Nope. When this happens to me, when I turn the key to START, the dashlights GO OUT. Could this still be the key switch? Or does this rule out the key switch? And implicate the PNP?

If that seems correct, where do I find the procedure to replace the PNP? Which is the original reason I started this thread.......:hissyfit:
 

greggraves

Original poster
Member
Mar 30, 2014
28
Still trying to talk myself OUT OF replacing the PNP switch ... but then I read this autorepair.about.com

"Bad Igntion Switch: If your battery checks out, but the starter is still silent, it may be a faulty ignition switch. Turn the key to the on position (not all the way to start). If the red warning lights on your dash don't light up (and your battery connections are clean), the ignition switch is bad. If they do light up, turn the key to the start position. The dash warning lights should turn off at this key position (most cars). If you're not sure, turn on the headlights. When you try to start the car, the lights should either dim (a lot) or turn off completely. If they do, your ignition switch should be ok. If not, the switch will need replacement. "

Point being, rephrasing above "If the dash lights turn off, your ignition switch should be ok." The lights turn off.
 

greggraves

Original poster
Member
Mar 30, 2014
28
Thanks Texan, at least I know somebody else is fussing with the PNP. Without psychic powers, figuring out an intermittent problem is the worst. I decided to quit trying to guess what might be wrong and bought all 3 parts: ignition switch, starter relay, and the PNP. It will probably be the starter. :eek:
 

C-ya

Member
Aug 24, 2012
1,098
When the truck doesn't start, what "fixes" it? Waiting? Trying again? Shifting the tranny into N from P? In the past, a bad NSS (Neutral Safety Switch) could be bypassed by shifting to N and starting the vehicle. It was usually caused by bad contacts in the P position.

Just tossing some thoughts out. If you can change your oil, I would imagine you can change the switch. Just be careful with the ball/socket connector. I would imagine there would be no adjusting to it to "fix" the old one or when installing the new one. Just unplug, unhook, unbolt, bolt, hook, plug and go. Have you read the procedure in the manual?


ETA: Texan's link caused me to add this edit. Mounting holes look like they offer some adjustment.
 

greggraves

Original poster
Member
Mar 30, 2014
28
oh!!

the last bit of that link says "If you have problems removing the wiring connectors from the switch, this is due to a sealer that GM used in the switch. It melts into the connectors making them impossible to remove. This will require replacement of the connectors as well."

That plug from GMNation is $70. Hope I am not facing that!!
 

TXBlazer

Member
Nov 21, 2011
533
Cypress, TEXAS USA
greggraves said:
Yes I understand the procedure, and in fact have the step by step GM diagnosis chart I downloaded off your site ... however, none of that does me any good when there is no problem, i.e., when there is no problem everything checks out fine, which is almost 100% of the time. I figure there are four things that are likely culprits: the starter relay ($11), the PNP switch ($48), the ignition switch ($45 plus dealing with the Antitheft), starter ($500 installed by shop). Bottom line is that I have to GUESS what is wrong and start replacing stuff. I know the PNP switch malfunction will reproduce what I am experiencing, are you saying that the ignition switch would reproduce the same thing?

In your post, you have after the ignition switch, dealing with the antitheft. I have not heard that replacing the ignition switch affects your antitheft system. At least when I replaced them on both of my TB's it didn't. Just pull the bottom half of the column cover off, remove and unplug the old switch, make note of where the gear teeth are positioned and replace with the new switch, I'm pretty sure that will correct your intermittent problem. There have literally been tons of these cheap little POS switches replaced, there are threads on TBSSOwners as well, about very similar symptoms. In all the ignition or no start threads I have read, or replied to, I haven't heard of anyone having to mess with the PNP switch, except for the guys who have swapped in a different transmission, and that problem was of their own doing.
 

C-ya

Member
Aug 24, 2012
1,098
greggraves said:
No. I don't have a manual other than the pdf manuals I got from gmtnation, which don't address the PNP switch. All I have is this site info for a 2001 Silverado

http://www.justanswer.com/chevy/36wik-change-neutral-safety-switch-2001-silverado.html

You think that is same general procedure as 2006 TB 2wd vehicle?

I'll check my Haynes when I get home for you and see what it says. I did a quick check in the download pdf's and nothing jumped out at me for the switch. It's probably in some obscure section like "Driveline lash adjustment" or "Front end alignment". (<---That's our color for sarcasm here.)
 

C-ya

Member
Aug 24, 2012
1,098
Texan said:
Goggle may be or may not be your friend. That link is for a Allision (sp) transmission.
Here is a picture of the PNP switch for your TB. It appears to be adjustable .


More Information for STANDARD MOTOR PRODUCTS NS319

Texan, that pic does look like it could be adjusted some. I'll see what the Haynes manual says - not that it is the be-all, end-all, last word on repairs, but until we can find it in the GM service manual, that's what I got.
 

RayVoy

Member
Nov 20, 2011
939
RayVoy said:
So we can break this down with a little thought........................

- if the relay was bad, the dash lights would not be impacted.
- ditto for the starter
- the ignition switch is a know failure item
- the PNR switch has not caused a reported (on this iste that I am aware of) failure.

After thinking about this, I may be considering changing my statements :undecided:

greggraves said:
when the key is rotated to ON the dashlights come on, then dashlights go out when turned to START position, no sounds, no clicks, no nothing, then :crazy:dashlights come back on when the key is returned to the ON position.
This could be normal :undecided:. It is very possible that the start circuit does turn off the dash lights I am sure the headlights get turned off when the key is moved to the crank/start position. Doing this would provide a little more juice for the starter.

THEREFORE; the items you have been worrying about may be fine. It could very well be the starter solenoid with a worn contact.

We need to have someone (or you) check their dashlights when the truck starts to see if the lights go out.
 

Texan

Member
Jan 14, 2014
622
When my TB goes to the start position, the warning lights on the cluster go out
and the instruments bottom out. I have not messed with my transmission (knock
on wood) other than filters and oil. I would guess that you would adjust the switch
(it appears to rotate a small amount) to insure that the indicator is correct on the
cluster. May be a two person job.
 

budwich

Member
Jun 16, 2013
2,027
kanata
I think if you look at the multitude of starting circuits that show "key positions", there are none that show battery voltage maintained to the "run" position when the key is further turned to the "start" position. Thus all circuits that require "run" voltage are unlikely to be functional.
 

C-ya

Member
Aug 24, 2012
1,098
Texan said:
I would guess that you would adjust the switch
(it appears to rotate a small amount)

Haynes manual does say it can adjust - but only if it starts in anyting but P or N.

Replacement looks straightforward in the plugs. The picture shows "normal" GM connectors with the locking tab, but it doesn't mention any kind of sealant. No differentiation made between years or 2WD/4WD.

Admins/moderator's: What's the policy for posting a page from the manual? If I credit it, is it OK? I can scan it and post it easily as it is on one page.
 

RayVoy

Member
Nov 20, 2011
939
RayVoy said:
We need to have someone (or you) check their dashlights when the truck starts to see if the lights go out.

Ok, it appears dash lights going out when key is in the START position.

RayVoy said:
It could very well be the starter solenoid with a worn contact..
If it is the starter solenoid, you will be able to hear a click (the solenoid operating) coming from the area of the starter whenever you experience the no start condition.


However, it could still be the ignition switch, not providing the command to start.
 

Texan

Member
Jan 14, 2014
622
In a couple of other post in the last two weeks, Rodie has listed all of the connections
at the ignition switch with the wire color codes. Some of them are hot in both run and start.

Pink and white stay hot in run and start.
 

IllogicTC

Member
Dec 30, 2013
3,452
RayVoy said:
Ok, it appears dash lights going out when key is in the START position.

2x confirmation, lights go out during the time it's in START and the gauges do a self-test. Also, if one quickly tips the key toward START without fully engaging and then dropping back, you can make the lights-out and the gauge test occur with no command sent. A bad ignition switch may mimic this behavior (not fully engaging the START position).
 

RayVoy

Member
Nov 20, 2011
939
IllogicTC said:
A bad ignition switch may mimic this behavior (not fully engaging the START position).
Yep, it's a toss-up between ignition switch and starter solenoid, but, I don't think it is the PNR switch.
 

greggraves

Original poster
Member
Mar 30, 2014
28
Thanks to all for the great perspectives. As far as my wife and I can remember, the NoStart intermittent situation does not generate the clicking you'd normally expect from the starter solenoid. I don't think that rules out the solenoid because maybe just intermittently goes to a "no start no do nothing" mode. Who knows? Certainly not me. I spent the $90 and have the three parts mentioned above in my possession. I am definitely going to replace the ignition switch and the relay (keeping the old one for grins). Whether or not I replace the PNP switch will depend on how lazy I am between now and when we leave. I am carrying all the meters etc. to test the circuits so if it does happen again post-switch-change I can measure whether voltage is getting to the solenoid or not. If yes, it is the solenoid-starter assembly; if no, it is the PNP switch (which I will have most likely in the glove compartment). Seems like a plan.
 

greggraves

Original poster
Member
Mar 30, 2014
28
I recd the switch yesterday. Following the advice given on Trailvoy [ How to replace your ignition switch (pics) ] thread. "Mellis" the poster says to 'disconnect the battery'. Per MAY03LT who posts on this site and Youtube

[ Trailblazer battery disconnect - side effects - YouTube ] he warns about NOT removing the negative battery because of the HVAC reset and that reset busting the door actuator. I know this is TRUE because I had my battery changed at Autozone and sure enough the actuator door broke which cost me in the end, with my wife raising holy hell with GM Headquarters, 300 bucks.

So what is the DANGER in not removing the neg cable while removing that switch? Or should I go buy a computer memory saver? I am not removing the battery wire in any case. Any thoughts?
 

Saul

Member
Jul 5, 2014
1
In the process of fixing the "Won't start" after driving somewhere and then it does not crank fiasco...I have now replaced the ignition switch about 8 times. I tried a Durolast from Autozone, which worked for about 4 months, then the issue came back so I bought an AC Delco through Amazon and the problem went away for 1 day, so I figured I would rule out the switch and look elsewhere. In the process of trouble shooting I looked at the igintion wiring diagram and found I could leave the igintion swithch in the Run position and then remove the Starter Relay under the hood for my 2003 Envoy XL, and bypass the relay with a custom jumper wire tool I made. It worked and it got me out of 2 jams where my car would not start. In the process of installing the Ignition switch I found that the gear or teeth location of the switch does not come preset ready to install. I got tired of removing the battery cable everytime I had to move the gear one tooth location to see if the car would start or if the ignition would stay on (with key out) because the igintion switch teeth were not set properly. Long story short, I got the swithc gear set correctly after 4 tries and did not have to remove the battery cable. I also suspected the relay has been the problem all along so I replaced the Ignition and Starter relays which are both the same and are next to each other.

Car has been working OK for 2 days in the 108F weather in Stockton CA, which usually agrevates the failure even more.

Good luck...
 

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