Service LTPWS Light - Page 2 - ZR-1 Net Registry Forums

WB9MCW · 08-27-2007

TT why does it light up every start up?? I only go abt 15mph for the one mile out of my private road so speed in not an issue since it turns the light off in abt 1/16 to 1/8 mi down the private drive.

QB93Z · 08-28-2007

Quote:

Originally Posted by tomtom72

Bryan, your issue may be a sticky or lazy fariday battery. If the thing don't slide easily then it doesn't generate enough electricity to transmit. Our sensors are just like those hookey flashlights...ya know the ones you gotta shake before they light up?

I have one, a right front, that acts out once in awhile. It sets the Service LTPWS light & if I drive fast enough for a while it goes out.

Tom

Tom, Thanks for the great explanation. For a long time I have wondered about how the transmitters worked.
Jim

WB9MCW · 08-29-2007

maybe mine just keeps tripping the LTPWS circuit and that is why my light keeps coming on at startup

GOLDCYLON · 08-29-2007

Quote:

Originally Posted by WB9MCW

maybe mine just keeps tripping the LTPWS circuit and that is why my light keeps coming on at startup

Thats possible I wonder if the LTPWS reader is the culprit vs one of the sensors?

zr1don · 08-29-2007

I have a 1990 that the LTPW lite would come on after 1/4 mi or so of driving. It has no wheel sensors. I removed the DIC bulb.

tomtom72 · 08-29-2007

Over at the Net Reg site in the How to section......if I remember right....

is a write up on how the sensors and the receiver works. If I remember right the sensor has an inductive battery and a capacitor to store juice, upon start up when the ECM goes thru its' testing routien it "listens" for all the sensors to report in. If the capacitor is failing or if the "battery" don't move freely the sensor may not have enough to "report in".

Like with mine it seems after bit of driving the Ser LTPWS light comes on, then after I drive for a while the light goes out buy itself or if I stop & shut down and re-start the light stays out maybe for awhile & comes back on or it stays out. The write up said that most of the false DTC's from the sensors were due to the battery not moving freely to make enough juice for the capacitor to store.....It has been a while since I read the write up so I proly don't have all the facts straight!

WB9MCW · 08-29-2007

Yes I read that whole description/write up too. But my problem is the inverse. Every time I fire the Z up the service light in on after a 1/16 mile poof out she goes like clockwork--so I figure all is OK by just have to wonder why does the light come on every start up?

My guess is that for some reason the ecm is triggered somehow to do this--not sure why this would be the case--just plain wierdness--good olde Murphy is hangin around my ecm or somewhere...

I was really wondering if anyone else has ever had such a strange cycle/rut as my Z is having.

tomtom72 · 08-30-2007

Bryan, two things come to mind.

The capacitor is not holding a charge long enough to report it on the next start up, like sitting overnight or longer.

The Fariday battery is weak.

I vote for the first guess because the light goes out quickly after start up & car movement. Unlike my issue which I suspect is the battery not moving freely enough to charge my capacitor quickly enough and that the capacitor maybe marginal at best.

It is my impression that the LTPWS along with everything else on the DIC goes thru a test directly after motor start up...or at least within the first few minutes after the motor is running. If there is no juice/or not enough juice to transmitt then the Service LTPWS light sets.

Tom

WB9MCW · 08-30-2007

That my dear TT is the "beacon of reality" I was looking for---an answer that makes sense--the cap is not holding my charge--yep I bet that is it--it must be real bad since it will come on even after a very short time of sitting---This weekend I will try multiple starts in a row and see if it comes on every time!!!
I suspect it will which means my cap must be really shot--well at least enough signal makes it to turn off the light once I get rolling---

sledutah · 08-31-2007

Quote:

Originally Posted by GOLDCYLON

Nope I heard all four need to come out on the 90-91s for the light to stay out. What year was the yellow one was the blub already removed from the DIC?

I took all 4 sensors out of my '91. After about 400 miles the light came on and stays on.

08-27-2007	#11
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,607	Re: Service LTPWS Light TT why does it light up every start up?? I only go abt 15mph for the one mile out of my private road so speed in not an issue since it turns the light off in abt 1/16 to 1/8 mi down the private drive. __________________ http://i119.photobucket.com/albums/o...9mcw/SIG-2.jpg http://i119.photobucket.com/albums/o128/wb9mcw/vcm.gif "The Budget should be balanced, the Treasury should be refilled, public debt should be reduced, the arrogance of officialdom should be tempered and controlled, and the assistance to foreign lands should be curtailed, lest Rome will become bankrupt. People must again learn to work instead of living on public assistance." - Cicero, 55 BC " We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution but to overthrow the men who pervert the Constitution." - Abraham Lincoln

08-29-2007	#13
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,607	Re: Service LTPWS Light maybe mine just keeps tripping the LTPWS circuit and that is why my light keeps coming on at startup __________________ http://i119.photobucket.com/albums/o...9mcw/SIG-2.jpg http://i119.photobucket.com/albums/o128/wb9mcw/vcm.gif "The Budget should be balanced, the Treasury should be refilled, public debt should be reduced, the arrogance of officialdom should be tempered and controlled, and the assistance to foreign lands should be curtailed, lest Rome will become bankrupt. People must again learn to work instead of living on public assistance." - Cicero, 55 BC " We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution but to overthrow the men who pervert the Constitution." - Abraham Lincoln

08-29-2007	#15
zr1don Join Date: Jan 2006 Location: Temecula, CA Posts: 92	Re: Service LTPWS Light I have a 1990 that the LTPW lite would come on after 1/4 mi or so of driving. It has no wheel sensors. I removed the DIC bulb.

08-29-2007	#16
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: Service LTPWS Light Over at the Net Reg site in the How to section......if I remember right.... is a write up on how the sensors and the receiver works. If I remember right the sensor has an inductive battery and a capacitor to store juice, upon start up when the ECM goes thru its' testing routien it "listens" for all the sensors to report in. If the capacitor is failing or if the "battery" don't move freely the sensor may not have enough to "report in". Like with mine it seems after bit of driving the Ser LTPWS light comes on, then after I drive for a while the light goes out buy itself or if I stop & shut down and re-start the light stays out maybe for awhile & comes back on or it stays out. The write up said that most of the false DTC's from the sensors were due to the battery not moving freely to make enough juice for the capacitor to store.....It has been a while since I read the write up so I proly don't have all the facts straight! __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

08-29-2007	#17
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,607	Re: Service LTPWS Light Yes I read that whole description/write up too. But my problem is the inverse. Every time I fire the Z up the service light in on after a 1/16 mile poof out she goes like clockwork--so I figure all is OK by just have to wonder why does the light come on every start up? My guess is that for some reason the ecm is triggered somehow to do this--not sure why this would be the case--just plain wierdness--good olde Murphy is hangin around my ecm or somewhere... I was really wondering if anyone else has ever had such a strange cycle/rut as my Z is having. __________________ http://i119.photobucket.com/albums/o...9mcw/SIG-2.jpg http://i119.photobucket.com/albums/o128/wb9mcw/vcm.gif "The Budget should be balanced, the Treasury should be refilled, public debt should be reduced, the arrogance of officialdom should be tempered and controlled, and the assistance to foreign lands should be curtailed, lest Rome will become bankrupt. People must again learn to work instead of living on public assistance." - Cicero, 55 BC " We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution but to overthrow the men who pervert the Constitution." - Abraham Lincoln

08-30-2007	#18
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: Service LTPWS Light Bryan, two things come to mind. The capacitor is not holding a charge long enough to report it on the next start up, like sitting overnight or longer. The Fariday battery is weak. I vote for the first guess because the light goes out quickly after start up & car movement. Unlike my issue which I suspect is the battery not moving freely enough to charge my capacitor quickly enough and that the capacitor maybe marginal at best. It is my impression that the LTPWS along with everything else on the DIC goes thru a test directly after motor start up...or at least within the first few minutes after the motor is running. If there is no juice/or not enough juice to transmitt then the Service LTPWS light sets. Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

08-30-2007	#19
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,607	Re: Service LTPWS Light That my dear TT is the "beacon of reality" I was looking for---an answer that makes sense--the cap is not holding my charge--yep I bet that is it--it must be real bad since it will come on even after a very short time of sitting---This weekend I will try multiple starts in a row and see if it comes on every time!!! I suspect it will which means my cap must be really shot--well at least enough signal makes it to turn off the light once I get rolling--- __________________ http://i119.photobucket.com/albums/o...9mcw/SIG-2.jpg http://i119.photobucket.com/albums/o128/wb9mcw/vcm.gif "The Budget should be balanced, the Treasury should be refilled, public debt should be reduced, the arrogance of officialdom should be tempered and controlled, and the assistance to foreign lands should be curtailed, lest Rome will become bankrupt. People must again learn to work instead of living on public assistance." - Cicero, 55 BC " We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution but to overthrow the men who pervert the Constitution." - Abraham Lincoln Last edited by WB9MCW; 09-01-2007 at 12:46 AM.

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