First off - I hope this isn't a repost, although it probably is as I
swear I remember reading something about this a few months ago. I
tried the search function SEVERAL times over the last few days
(honest!) but I keep getting a SQL error:





<font face="Arial" size="2">Microsoft OLE DB Provider for SQL Server</font> <font face="Arial" size="2">error '80040e31'</font>




<font face="Arial" size="2">Timeout expired</font>




<font face="Arial" size="2">/forum/search.asp</font><font face="Arial" size="2">, line 370

</font>


<font face="Arial" size="2">ANYWHO

</font>


<font face="Arial" size="2">I've noticed over the last week or two,
as temps have dropped here in Chicago, that my glow plug lamp seems to
stay lit a LONG time for the first start of the morning (temps in the
lower 40s.) It's on for at LEAST 30 seconds.

</font>


<font face="Arial" size="2">When I bought my truck back in April, we
had some cooler mornings - and I recall wondering if there even WAS a
glow-plug light on the dash, because it was on and off so fast I'd
never even see it.

</font>


<font face="Arial" size="2">It's only on for extended periods when
the truck is totally cold. First start of the morning, or when I
start it in the evening for the trip home from the office (and the
truck has been sitting for 8+ hours.)

</font>


<font face="Arial" size="2">I didn't have the truck for very long in
the spring before temps started to warm up around here, so I'm not
entirely sure what is "normal". How long to some of you folks
wait for the lamp to go out... and should I take it into the dealer to
be looked at?

</font>


<font face="Arial" size="2">TIA....

</font>


<font face="Arial" size="2">Jim

</font>

I'd take it in for a looksee. Is it staying on after it's started
or are you waiting for it to go out after 30 seconds and then starting
it. Mine has been going on only for about 2 seconds on below freezing
days. IIRC the owners manual says it should only go on for 3-5
seconds or something like that.

I'd take it in for a looksee. Is it staying on after it's started
or are you waiting for it to go out after 30 seconds and then starting
it. Mine has been going on only for about 2 seconds on below freezing
days. IIRC the owners manual says it should only go on for 3-5
seconds or something like that.




I always wait for the light to go out before I start it.



And I *thought* that the appropriate lamp-on time was ~2 seconds.
Good thing it wasn't just something my imagination conjured up
;) I'll go dig in my owners manual to make sure... if it says 3-5
seconds, then at least I have a leg to stand on if I take it into the
dealer.

Edited by: OmniGLH

I'd take it in for a looksee. Is it staying on after it's started
or are you waiting for it to go out after 30 seconds and then starting
it. Mine has been going on only for about 2 seconds on below freezing
days. IIRC the owners manual says it should only go on for 3-5
seconds or something like that.




I always wait for the light to go out before I start it.



And I *thought* that the appropriate lamp-on time was ~2 seconds.
Good thing it wasn't just something my imagination conjured up
;) I'll go dig in my owners manual to make sure... if it says 3-5
seconds, then at least I have a leg to stand on if I take it into the
dealer.





Checked my manual - it doesn't address the time but describes it as a
"fast warm-up glow plug system" still, 30 sec's seems
extensive. Just a thought....are your batteries weak??

I have seen temperatures well below freezing (around 20 this morning) My glow plugs were on for a maximum of 2 seconds this morning.

You must have something wrong.

My truck is at the dealer because it had some codes on it. One of the problems I took it in for was long glow plug burn times! Turns out that the glow plug controller was 'Pooched"! They sent a new one from a dealer in Cali. to my dealer in Unionville Ontario. I will be picking it up on Monday and I will see if everything is OK! Also had the ECM replaced I don't know if the two are related.I will try to let you know. Edited by: joeking

My controller went out too. It was doing the same thing but sometimes the light would never go out. It would start anyway. It was warm then. They found the controller wouldn't wake up so they replaced it.

Here is what GM says about the fast warm-up glow plug system. "The new silver tipped glow plugs (LB7's were gold) are designed to reach 1000°C (1832°F) in just 1.8 seconds, and then PWM (pulse width modulation) is used to maintain that temperature for the remainder of the three seconds. In addition, each new fuel injector has one of its seven spray holes oriented to spray directly onto the heated glow plug tip. Total glow system current draw peaks at 110 amps for the 1.8 second initial heat cycle, then the current is reduced to 30 amps for the remaining 1.2 seconds to maintain the 1000° temperature." Sounds like your controler is bad like others mentioned.I would take it in to be checked out. Good luck

mine had to be replaced also

Glow plug question:



At what point in the ignition process do the glow plugs actually start to heat up?



What I mean is....you turn on the key, the "wait to start light goes on
then off, then you turn the ignition to start. What is happening
during the time the light is on and once the "wait to start light"
turns off? Are the plugs hot at this point? Do they keep
drawing more current? Does it do any damage to anything if the
key is left on after this point w/o starting the engine??



Rob

Mine is getting replaced today, dealer called and said new module was in. Hope there isn't any other problems because of this http://www.dieselplace.com/forum/smileys/smiley5.gif Truck seemed to start pretty hard, starting to get pretty cold mornings.

They stay on, but at a reduced power level. It does mention
something in the owner's manual about not leaving the key in 'run' for
extended periods, because of damage to the glow plugs and to keep from
draining the batteries.



Dennis